El género Chenopodium está integrado por numerosas especies y subespecies y por tipos cultivados ... more El género Chenopodium está integrado por numerosas especies y subespecies y por tipos cultivados y silvestres. Entre las especies cultivadas se encuentra la quinua (Chenopodium quinoa Willd.), la cañahua (Ch. pallidicaule Aellen) y los cultivares Kelite y Chía (Ch. nuttalliae Safford). De estas tres especies cultivadas, la quinua es el cultivo de mayor importancia (Bonifacio 2001). La quinua es una planta alotetraploide (2n=4x=36), muestra una herencia disómica para la mayoría de los caracteres cualitativos (Simmonds 1971, Risi y Galwey 1984, Ward 2000) y es esencialmente autógama.
La quinua fue domesticada en Bolivia, en inmediaciones del lago Titicaca (Gandarillas, 1986) hace mas o menos 6000 años atrás. Desde este centro de domesticación, su cultivo se ha extendido por toda la cordillera de los Andes. Actualmente la quinua se cultiva en Argentina, Chile, Bolivia, Perú, Ecuador y Colombia, siendo Bolivia el principal país productor. Se la cultiva desde el nivel del mar hasta los 4,000 m. Su período de crecimiento varía entre 90 y 220 días, dependiendo de las variedades. Produce aproximadamente entre 1 y 5 t/ha de semillas.
En Bolivia la quinua se produce principalmente en el altiplano y de forma marginal en los valles interandinos. Desde el punto de vista agro-ecológico, el altiplano boliviano puede ser dividido en tres regiones: Altiplano Norte, Centro, y Sur. En el Altiplano Norte, el sistema productivo esta basado en el cultivo de papa, quinua, cebada y avena. La producción de papa y quinua está destinada principalmente al consumo familiar. El principal factor limitante para la producción de quinua en esta región es la enfermedad del mildeu (Peronosproa farinosa) que puede reducir los rendimientos hasta en un 99% (Danielsen et al., 2000). Otro factor que desalienta la producción de quinua en esta zona es la baja calidad del grano de las variedades nativas (tamaño pequeño del grano que no es apreciado en el mercado de exportación).
En el Altiplano Central el sistema de producción está basado en la rotación de cultivos de papa, quinua y forrajeras. Las variedades de quinua cultivadas en esta zona son de ciclo semi-tardío y tardío, de grano pequeño a mediano. La quinua representa el 30% del ingreso anual del agricultor. Los principales factores limitantes de la producción de quinua en esta región son las enfermedades fungosas (mildiú) y las plagas. Entre las plagas se tienen a los gusanos cortadores o “ticonas” (Feltia spp., Agrotis spp. y Spodoptera spp.), y “kona-konas” que son larvas de la polilla de la quinua (Eurysacca quinoae).
En el Altiplano Sur las condiciones climáticas son extremas, la región es muy árida (precipitación anual promedio de 200 mm), con alto riesgo de heladas. Los suelos son generalmente arenosos, de baja fertilidad y afectados por la salinidad. En algunos casos, un período prolongado de sequía puede ocasionar la pérdida total del cultivo. La quinua es el único cultivo capaz de tolerar satisfactoriamente estas condiciones climáticas. Aparte de su importancia en la dieta diaria de la población del Altiplano Sur, la quinua es una fuente importante de ingresos para los pobladores, representando cerca de la mitad de su ingreso anual. Actualmente existen numerosas empresas y organización de productores que se dedican al beneficiado y comercialización de la quinua. El 60% de la producción de quinua de esta región es destinada a mercados domésticos y de exportación.
La colección Boliviana de quinua cuenta en la actualidad con más 3000 accesiones, siendo la más grande del mundo, la misma que se conserva en la estación experimental de Quipa-Quipani (La Paz). Las accesiones provienen del Altiplano Sur, Centro y Norte, de los valles interandinos. Adicionalmente se cuenta con accesiones del Norte Peruano, de Argentina y Chile, y una colección internacional. Esta colección ha sido caracterizada morfológicamente y evaluada para numerosos caracteres de interés agronómico y económico.
Si bien existe la creencia generalizada de que en los bancos de germoplasma se encuentran genes útiles para mejorar los cultivos, la realidad muestra que los científicos no han tenido mucho éxito en identificar e incorporar esos genes a cultivos comerciales (Tanksley y McCouch, 1997). La mayoría de las accesiones de los bancos de germoplasma no han contribuido, en la medida que se espera, a las variedades modernas, particularmente en lo que respecta a los caracteres complejos, como son el rendimiento, la calidad, etc. Esto se debe en gran parte a que la caracterización y utilización del germoplasma ha estado exclusivamente basado en la búsqueda del fenotipo apropiado. Sin embargo, existen evidencias que demuestran que la diversidad genética almacenada en los bancos de germoplasma puede ser aprovechada con una eficiencia nunca antes imaginada, si no se toma en cuenta a priori el fenotipo apropiado como criterio de elección. Así por ejemplo, se ha comprobado, mediante técnicas moleculares, que en arroces de bajo rendimiento existen genes para aumentar el rendimiento (Xiao et al. 1996).
En consecuencia, es importante complementar las caracterizaciones y evaluaciones fenotípicas con estudios similares a nivel molecular, para un mejor aprovechamiento del germoplasma conservado. En esta perspectiva, mediante esta actividad, se ha caracterizado molecularmente más de 2500 accesiones de quinua.
Clonal propagation and sexual reproduction have diametrically opposite effects on the genetic div... more Clonal propagation and sexual reproduction have diametrically opposite effects on the genetic diversity of crops, permitting, respectively, the conservation of existing genotypes or the creation of new diversity. Oxalis tuberosa Mol. (''oca'') exhibits a heteromorphic self-incompatibility system and is traditionally propagated clonally but is capable of sexual reproduction. In this study we investigated the influence of sexual reproduction on the in situ genetic diversity of a vegetatively propagated crop, taking oca as a model plant. The occurrence of sexual reproduction in natural conditions and its use by farmers were studied through surveys and interviews, while the effect of sexual reproduction on the in situ genetic diversity was evaluated using microsatellite analysis. Plantlets issuing from sexual reproduction were encountered in five of the nine visited communities. The interviews indicated that six out of the nine interviewed farmers were likely, albeit unconsciously, incorporating clonal lineages issuing from sexual reproduction into their varieties. The microsatellite analysis indicated a strong effect of such incorporations on the genetic diversity of the plant varieties. Assignment tests confirmed the allogamy of oca. ''Complex varieties'', made up of individuals exhibiting genetically differentiated genotypes, were most likely the result of recent crossing. Unconscious incorporation of new genotypes into the cultivated oca germplasm is therefore highly likely, raising the question of its potential occurrence in other vegetatively propagated crops. These findings could have an important effect on the adaptive potential of oca, especially in light of the genetic erosion that threatens the crop.
Quinoa (Chenopodium quinoa Willd.) is an important seed crop throughout the Andean region of Sout... more Quinoa (Chenopodium quinoa Willd.) is an important seed crop throughout the Andean region of South America. It is important as a regional food security crop for millions of impoverished rural inhabitants of the Andean Altiplano (high plains). Efforts to improve the crop have led to an increased focus on genetic research. We report the identifi cation of 14,178 putative single nucleotide polymorphisms (SNPs) using a genomic reduction protocol as well as the development of 511 functional SNP assays. The SNP assays are based on KASPar genotyping chemistry and were detected using the Fluidigm dynamic array platform. A diversity screen of 113 quinoa accessions showed that the minor allele frequency (MAF) of the SNPs ranged from 0.02 to 0.50, with an average MAF of 0.28. Structure analysis of the quinoa diversity panel uncovered the two major subgroups corresponding to the Andean and coastal quinoa ecotypes.
Can˜ahua (Chenopodium pallidicaule
Aellen) is a poorly studied, annual subsistence crop
of the hi... more Can˜ahua (Chenopodium pallidicaule Aellen) is a poorly studied, annual subsistence crop of the high Andes of South America. Its nutritional value (high in protein and mineral content) and ability to thrive in harsh climates make it an important regional food crop throughout the Andean region. The objectives of this study were to develop genetic markers and to quantify genetic diversity within can˜ahua. A set of 43 wild and cultivated can˜ahua genotypes and two related species (Chenopodium quinoa Willd. and Chenopodium petiolare Kunth) were evaluated for polymorphism using 192 microsatellite markers derived from random genomic can˜ahua sequences produced by 454 pyrosequencing of can˜ahua genomic DNA. Another 424 microsatellite markers from C. quinoa were also evaluated for cross-species amplification and polymorphism in can˜ahua. A total of 34 polymorphic microsatellite marker loci were identified which detected a total of 154 alleles with an average of 4.5 alleles per marker locus and an average heterozygosity value of 0.49. A cluster analysis, based on Nei genetic distance, clearly separated from wild can˜ahua genotypes from the cultivated genotypes. Within the cultivated genotypes, subclades were partitioned by AMOVA analysis into six model-based clusters, including a subclade consisting sole of erect morphotypes. The isolation by distance test displayed no significant correlation between geographic collection origin and genotypic data, suggesting that can˜ahua populations have moved extensively, presumably via ancient food exchange strategies among native peoples of the Andean region. The molecular markers reported here are a significant resource for ongoing efforts to characterize the extensive Bolivian and Peruvian can˜ahua germplasm banks, including the development of core germplasm collections needed to support emerging breeding programs.
Oxylipins constitute a class of molecules notably involved in hostepathogen interactions. In the ... more Oxylipins constitute a class of molecules notably involved in hostepathogen interactions. In the potato-Phytophthora infestans (Mont.) De Barry (P. infestans) relationships, the role of colneleic and colnelenic acids, two oxylipins resulting from the consecutive action of lipoxygenase (EC 1.13.11.12) and divinyl ether synthase (EC 1.-) on respectively linoleic and linolenic acids have been previously reported. In the present paper, five potato cultivars with contrasting resistance to P. infestans were submitted to infection. Lipoxygenase pathway response was studied at both transcriptional and metabolic levels. A Northern blot preliminary study revealed that lipoxygenase (lox1 and lox3) and divinyl ether syn-thase genes were clearly up-regulated 96 h after leaf inoculation with P. infestans. Profiling of free and esterified oxylipins performed 24 h, 48 h, 72 h and 96 h after inoculation, showed that esterified oxylipins are mainly produced with 9-derivatives in higher concentrations (esterified forms of colnelenic acid, 9-hydroxy octadecatrienoic acid, 9-hydroperoxy octadecatrienoic acid). Oxylipin accumulation is undetectable 24 h after infection, slightly detectable after 48 h, reaching highest concentrations after 96 h. Cultivars show slightly different oxylipin profiles but the concentration of individual oxylipins differs markedly 96 h after infection. No correlation was found between P. infestans resistance levels and oxylipin synthesis rates or concentration. To assess local and systemic effects of colneleic acid application before P. infestans infection, Bintje cultivar was sprayed with colneleic acid 72 h before inoculation. Both application modes (local and systemic) resulted in lipoxygenase pathway activation without affecting the resistance level to the pathogen.
Oxalis tuberosa is a vegetatively propagated
tuber crop in the Andes. The peasants cultivate a gr... more Oxalis tuberosa is a vegetatively propagated tuber crop in the Andes. The peasants cultivate a great number of varieties for which genetic homogeneity has never been demonstrated. Morphological descriptors and ISSR markers were used to determine the intravarietal diversity and the influence of the mode of conservation ex-situ vs in-situ. Molecular markers revealed an intra-varietal genetic diversity attesting that oca varieties are not pure clones. The morphological analysis was congruent with the peasant classification, contrary to the molecular markers. The comparison between both conservation strategies revealed a larger intra-varietal diversity in in-situ conditions and a genetic divergence between plants. The traditional practices are likely to be responsible of the intra-varietal polymorphism since the oca is propagated almost exclusively vegetatively. At the conservation level, differences could be explained by the sampling methods. A more integrated approach between genebanks and in-situ conservation is recommended to maintain the genetic resources of the species.
molecular markers have been
used to investigate genetic diversity of oca
(Oxalis tuberosa Mol.), ... more molecular markers have been used to investigate genetic diversity of oca (Oxalis tuberosa Mol.), an Andean neglected tuber crop species. Sampling procedure allowed a preliminary study of the genetic diversity at the intra- and intervarietal levels. Twenty tuber lots conserved in situ in the microcentre of Candelaria and ex situ in the Toralapa Centre (Bolivia) were identified. Four ISSR primers amplified a total of 25 fragments of which 17 (68%) were polymorphic. These experiments show that the structure of oca varieties is mainly based upon vernacular names with a greater differentiation among tuber lots than within them, supporting agromorphological data. ISSR technique enlightened the existence of heterogeneous varieties in oca and divergence between in situ and ex situ conservation strategies. These observations are potentially linked to the different ways of management of tubers in these two conservation systems.
Quinoa (Chenopodium quinoaWilld.) is a widely consumed food crop and a primary protein source for... more Quinoa (Chenopodium quinoaWilld.) is a widely consumed food crop and a primary protein source for many of the indigenous inhabitants of the Andean region of South America. In this study, we report the development of immature seed and floral expressed sequenced tag (EST) libraries and the identification of single nucleotide polymorphisms (SNPs) for quinoa. A total of 424 cDNA clones derived from immature seed and floral tissue were sequenced and analyzed for homology with known gene sequences. Three hundred and eleven of the clones were identified as homologues of known plant proteins, 38 were homologous to Arabidopsis proteins with no known function and 75 do not share significant homology with any protein in the queried databases. Interestingly, several of the annotated ESTs were present in relatively high abundance and have putative functions related to plant defense. Based on EST sequence information, fragments of 34 ESTs were amplified and sequenced in five quinoa accessions and one related weed species, C. berlandieri. Analysis of the quinoa EST sequences revealed a total of 51 SNPs in 20 EST sequences, including 38 single-base changes and 13 insertions–deletions (indels), with an average 1 SNP per 462 base pairs (bp) and 1 indel per 1812 bp. When the C. berlandieri accession was included in the analysis, 29 of the EST clones screened had at least one SNP present and an additional 81 SNPs were identified, bringing the total number of SNPs discovered to 132 (1 per 179 bp). The EST clones and SNP markers identified in this manuscript are of particular value in ongoing efforts to characterize gene expression and regulation associated with seed development, while the SNPs identified have immediate application for genetic mapping experiments, germplasm development, and the investigation of evolutionary relationships within the genus Chenopodium. # 2004 Elsevier Ireland Ltd. All rights reserved.
The nucleolus organizer region (NOR) and 5S ribosomal RNA (rRNA) genes are valuable as chromosome... more The nucleolus organizer region (NOR) and 5S ribosomal RNA (rRNA) genes are valuable as chromosome landmarks and in evolutionary studies. The NOR intergenic spacers (IGS) and 5S rRNA nontranscribed spacers (NTS) were PCR-amplified and sequenced from 5 cultivars of the Andean grain crop quinoa (Chenopodium quinoa Willd., 2n = 4x = 36) and a related wild ancestor (C. berlandieri Moq. subsp. zschackei (Murr) A. Zobel, 2n = 4x = 36). Length heterogeneity observed in the IGS resulted from copy number difference in subrepeat elements, small rearrangements , and species-specific indels, though the general sequence composition of the 2 species was highly similar. Fifteen of the 41 sequence polymorphisms identified among the C. quinoa lines were synapomorphic and clearly differentiated the highland and lowland ecotypes. Analysis of the NTS sequences revealed 2 basic NTS sequence classes that likely originated from the 2 allopolyploid subgenomes of C. quinoa. Fluorescence in situ hybridization (FISH) analysis showed that C. quinoa possesses an interstitial and a terminal pair of 5S rRNA loci and only 1 pair of NOR, suggesting a reduction in the number of rRNA loci during the evolution of this species. C. berlandieri exhibited variation in both NOR and 5S rRNA loci without changes in ploidy. Résumé : L'organisateur nucléolaire (NOR) et les gènes codant pour les ARN ribosomiques 5S sont utiles comme re-pères chromosomiques et pour des études sur l'évolution. Les espaceurs intergéniques (IGS) des NOR et les espaceurs non-transcrits (NTS) des ARNr 5S ont été amplifiés et séquencés chez 5 cultivars du quinoa (Chenopodium quinoa Willd., 2n = 4x = 36), une pseudocéréale des Andes, et un ancêtre sauvage (C. berlandieri Moq. subsp. Zschakei (Murr) A. Zobel, 2n = 4x = 36). Une hétérogénéité de taille a été observée chez les IGS en raison d'une différence quant au nombre de copies des sous-répétitions, de petits réarrangements et d'indels spécifiques d'une espèce. En géné-ral, cependant, la composition des séquences était très semblable entre les 2 espèces. Quinze des 41 polymorphismes identifiés au sein des lignées de C. quinoa étaient synapomorphes et distinguaient clairement les écotypes des bas-fonds de ceux de montagne. Une analyse des séquences NTS a révélé 2 classes de séquences NTS qui dérivent vrai-semblablement des 2 sous-génomes allopolyploïdes du C. quinoa. Une hybridation in situ en fluorescence (FISH) a montré que le C. quinoa possède 2 paires de locus d'ARNr 5S, l'une terminal et l'autre interne, mais 1 seule paire de locus NOR, ce qui suggère une réduction du nombre de locus d'ARNr au cours de l'évolution de cette espèce. Le C. berlandieri montrait une variation au niveau des locus NOR et d'ARNr 5S sans qu'il y ait de changement de ploïdie.
Resumen. Las especies silvestres de tomate presentan genes que podrían elevar la calidad de los c... more Resumen. Las especies silvestres de tomate presentan genes que podrían elevar la calidad de los cultivos y su valor nutricional. El objetivo del trabajo fue estudiar la di-versidad genética del tomate silvestre (Solanum spp.) a nivel morfológico y molecular a fin de diseñar estrategias de conservación y uso eficiente de genes de interés agro-nómico. Se analizó, a nivel morfológico, características de la planta, flor y fruto. Para el análisis molecular, se utilizó tejido de hoja para la extracción de ADN. Se realizó un análisis de componentes principales y la construcción de un clúster con datos morfo-lógicos. Estos análisis generaron un grupo formado por especies silvestres var. ceraci-forme repatriadas del Centro de Recursos Genéticos de Tomate (TGRC) y las silves-tres colectadas en Bolivia S. neorickii (código CPL), el otro grupo, formado por varie-dades ceraciformes (código CL) y una cultivada colectada en Bolivia. El análisis molecular confirmó la formación de dos grupos con mayor claridad, un grupo formado por accesiones colectadas denominadas S. neorickii (código CPL) más relacionadas con S. chmielewskii, el segundo grupo formado por las especies S. lycopersicum var. ce-raciforme. Las accesiones clasificadas como S. neorickii están más relacionadas a la especie S. chmielewski, pudiéndose concluir que podrían pertenecer a esta ultima especie. Abstract. Morphological and molecular study of genetic diversity of bolivian wild tomato (Solanum spp.) Wild tomato species have genes that could improve the quality of crops and their nutritional value. The objective was to study the genetic diversity of wild tomato (Solanum spp.) to morphological and molecular level in order to devise strategies for the conservation and efficient use of genes of agronomic interest. For this was analyzed morphologically characteristics of the plant, flower and fruit. For the molecular analysis of leaf tissue for DNA extraction was used. Principal component analysis and the construction of a cluster with morphological data were performed. These analyzes generated two groups: the first group of wild species var. ceraciforme repatriated from Tomato Genetics Resource Center (TGRC) and wild S. neorickii collected in Bolivia (CPL code), the second group, consisting ceraciformes varieties (CL code) and cultivated collected in Bolivia. Molecular analysis confirmed the formation of two groups more clearly: a group of accessions collected called S. neorickii (CPL code) more related to S. chmielewskii, the second group consists of the species S. lycopersi-cum var. ceraciforme. Accessions classified as S. neorickii are more related to the species S. Chmielewski, it can be concluded that belong to the latter species.
El género Chenopodium está integrado por numerosas especies y subespecies y por tipos cultivados ... more El género Chenopodium está integrado por numerosas especies y subespecies y por tipos cultivados y silvestres. Entre las especies cultivadas se encuentra la quinua (Chenopodium quinoa Willd.), la cañahua (Ch. pallidicaule Aellen) y los cultivares Kelite y Chía (Ch. nuttalliae Safford). De estas tres especies cultivadas, la quinua es el cultivo de mayor importancia (Bonifacio 2001). La quinua es una planta alotetraploide (2n=4x=36), muestra una herencia disómica para la mayoría de los caracteres cualitativos (Simmonds 1971, Risi y Galwey 1984, Ward 2000) y es esencialmente autógama.
La quinua fue domesticada en Bolivia, en inmediaciones del lago Titicaca (Gandarillas, 1986) hace mas o menos 6000 años atrás. Desde este centro de domesticación, su cultivo se ha extendido por toda la cordillera de los Andes. Actualmente la quinua se cultiva en Argentina, Chile, Bolivia, Perú, Ecuador y Colombia, siendo Bolivia el principal país productor. Se la cultiva desde el nivel del mar hasta los 4,000 m. Su período de crecimiento varía entre 90 y 220 días, dependiendo de las variedades. Produce aproximadamente entre 1 y 5 t/ha de semillas.
En Bolivia la quinua se produce principalmente en el altiplano y de forma marginal en los valles interandinos. Desde el punto de vista agro-ecológico, el altiplano boliviano puede ser dividido en tres regiones: Altiplano Norte, Centro, y Sur. En el Altiplano Norte, el sistema productivo esta basado en el cultivo de papa, quinua, cebada y avena. La producción de papa y quinua está destinada principalmente al consumo familiar. El principal factor limitante para la producción de quinua en esta región es la enfermedad del mildeu (Peronosproa farinosa) que puede reducir los rendimientos hasta en un 99% (Danielsen et al., 2000). Otro factor que desalienta la producción de quinua en esta zona es la baja calidad del grano de las variedades nativas (tamaño pequeño del grano que no es apreciado en el mercado de exportación).
En el Altiplano Central el sistema de producción está basado en la rotación de cultivos de papa, quinua y forrajeras. Las variedades de quinua cultivadas en esta zona son de ciclo semi-tardío y tardío, de grano pequeño a mediano. La quinua representa el 30% del ingreso anual del agricultor. Los principales factores limitantes de la producción de quinua en esta región son las enfermedades fungosas (mildiú) y las plagas. Entre las plagas se tienen a los gusanos cortadores o “ticonas” (Feltia spp., Agrotis spp. y Spodoptera spp.), y “kona-konas” que son larvas de la polilla de la quinua (Eurysacca quinoae).
En el Altiplano Sur las condiciones climáticas son extremas, la región es muy árida (precipitación anual promedio de 200 mm), con alto riesgo de heladas. Los suelos son generalmente arenosos, de baja fertilidad y afectados por la salinidad. En algunos casos, un período prolongado de sequía puede ocasionar la pérdida total del cultivo. La quinua es el único cultivo capaz de tolerar satisfactoriamente estas condiciones climáticas. Aparte de su importancia en la dieta diaria de la población del Altiplano Sur, la quinua es una fuente importante de ingresos para los pobladores, representando cerca de la mitad de su ingreso anual. Actualmente existen numerosas empresas y organización de productores que se dedican al beneficiado y comercialización de la quinua. El 60% de la producción de quinua de esta región es destinada a mercados domésticos y de exportación.
La colección Boliviana de quinua cuenta en la actualidad con más 3000 accesiones, siendo la más grande del mundo, la misma que se conserva en la estación experimental de Quipa-Quipani (La Paz). Las accesiones provienen del Altiplano Sur, Centro y Norte, de los valles interandinos. Adicionalmente se cuenta con accesiones del Norte Peruano, de Argentina y Chile, y una colección internacional. Esta colección ha sido caracterizada morfológicamente y evaluada para numerosos caracteres de interés agronómico y económico.
Si bien existe la creencia generalizada de que en los bancos de germoplasma se encuentran genes útiles para mejorar los cultivos, la realidad muestra que los científicos no han tenido mucho éxito en identificar e incorporar esos genes a cultivos comerciales (Tanksley y McCouch, 1997). La mayoría de las accesiones de los bancos de germoplasma no han contribuido, en la medida que se espera, a las variedades modernas, particularmente en lo que respecta a los caracteres complejos, como son el rendimiento, la calidad, etc. Esto se debe en gran parte a que la caracterización y utilización del germoplasma ha estado exclusivamente basado en la búsqueda del fenotipo apropiado. Sin embargo, existen evidencias que demuestran que la diversidad genética almacenada en los bancos de germoplasma puede ser aprovechada con una eficiencia nunca antes imaginada, si no se toma en cuenta a priori el fenotipo apropiado como criterio de elección. Así por ejemplo, se ha comprobado, mediante técnicas moleculares, que en arroces de bajo rendimiento existen genes para aumentar el rendimiento (Xiao et al. 1996).
En consecuencia, es importante complementar las caracterizaciones y evaluaciones fenotípicas con estudios similares a nivel molecular, para un mejor aprovechamiento del germoplasma conservado. En esta perspectiva, mediante esta actividad, se ha caracterizado molecularmente más de 2500 accesiones de quinua.
Clonal propagation and sexual reproduction have diametrically opposite effects on the genetic div... more Clonal propagation and sexual reproduction have diametrically opposite effects on the genetic diversity of crops, permitting, respectively, the conservation of existing genotypes or the creation of new diversity. Oxalis tuberosa Mol. (''oca'') exhibits a heteromorphic self-incompatibility system and is traditionally propagated clonally but is capable of sexual reproduction. In this study we investigated the influence of sexual reproduction on the in situ genetic diversity of a vegetatively propagated crop, taking oca as a model plant. The occurrence of sexual reproduction in natural conditions and its use by farmers were studied through surveys and interviews, while the effect of sexual reproduction on the in situ genetic diversity was evaluated using microsatellite analysis. Plantlets issuing from sexual reproduction were encountered in five of the nine visited communities. The interviews indicated that six out of the nine interviewed farmers were likely, albeit unconsciously, incorporating clonal lineages issuing from sexual reproduction into their varieties. The microsatellite analysis indicated a strong effect of such incorporations on the genetic diversity of the plant varieties. Assignment tests confirmed the allogamy of oca. ''Complex varieties'', made up of individuals exhibiting genetically differentiated genotypes, were most likely the result of recent crossing. Unconscious incorporation of new genotypes into the cultivated oca germplasm is therefore highly likely, raising the question of its potential occurrence in other vegetatively propagated crops. These findings could have an important effect on the adaptive potential of oca, especially in light of the genetic erosion that threatens the crop.
Quinoa (Chenopodium quinoa Willd.) is an important seed crop throughout the Andean region of Sout... more Quinoa (Chenopodium quinoa Willd.) is an important seed crop throughout the Andean region of South America. It is important as a regional food security crop for millions of impoverished rural inhabitants of the Andean Altiplano (high plains). Efforts to improve the crop have led to an increased focus on genetic research. We report the identifi cation of 14,178 putative single nucleotide polymorphisms (SNPs) using a genomic reduction protocol as well as the development of 511 functional SNP assays. The SNP assays are based on KASPar genotyping chemistry and were detected using the Fluidigm dynamic array platform. A diversity screen of 113 quinoa accessions showed that the minor allele frequency (MAF) of the SNPs ranged from 0.02 to 0.50, with an average MAF of 0.28. Structure analysis of the quinoa diversity panel uncovered the two major subgroups corresponding to the Andean and coastal quinoa ecotypes.
Can˜ahua (Chenopodium pallidicaule
Aellen) is a poorly studied, annual subsistence crop
of the hi... more Can˜ahua (Chenopodium pallidicaule Aellen) is a poorly studied, annual subsistence crop of the high Andes of South America. Its nutritional value (high in protein and mineral content) and ability to thrive in harsh climates make it an important regional food crop throughout the Andean region. The objectives of this study were to develop genetic markers and to quantify genetic diversity within can˜ahua. A set of 43 wild and cultivated can˜ahua genotypes and two related species (Chenopodium quinoa Willd. and Chenopodium petiolare Kunth) were evaluated for polymorphism using 192 microsatellite markers derived from random genomic can˜ahua sequences produced by 454 pyrosequencing of can˜ahua genomic DNA. Another 424 microsatellite markers from C. quinoa were also evaluated for cross-species amplification and polymorphism in can˜ahua. A total of 34 polymorphic microsatellite marker loci were identified which detected a total of 154 alleles with an average of 4.5 alleles per marker locus and an average heterozygosity value of 0.49. A cluster analysis, based on Nei genetic distance, clearly separated from wild can˜ahua genotypes from the cultivated genotypes. Within the cultivated genotypes, subclades were partitioned by AMOVA analysis into six model-based clusters, including a subclade consisting sole of erect morphotypes. The isolation by distance test displayed no significant correlation between geographic collection origin and genotypic data, suggesting that can˜ahua populations have moved extensively, presumably via ancient food exchange strategies among native peoples of the Andean region. The molecular markers reported here are a significant resource for ongoing efforts to characterize the extensive Bolivian and Peruvian can˜ahua germplasm banks, including the development of core germplasm collections needed to support emerging breeding programs.
Oxylipins constitute a class of molecules notably involved in hostepathogen interactions. In the ... more Oxylipins constitute a class of molecules notably involved in hostepathogen interactions. In the potato-Phytophthora infestans (Mont.) De Barry (P. infestans) relationships, the role of colneleic and colnelenic acids, two oxylipins resulting from the consecutive action of lipoxygenase (EC 1.13.11.12) and divinyl ether synthase (EC 1.-) on respectively linoleic and linolenic acids have been previously reported. In the present paper, five potato cultivars with contrasting resistance to P. infestans were submitted to infection. Lipoxygenase pathway response was studied at both transcriptional and metabolic levels. A Northern blot preliminary study revealed that lipoxygenase (lox1 and lox3) and divinyl ether syn-thase genes were clearly up-regulated 96 h after leaf inoculation with P. infestans. Profiling of free and esterified oxylipins performed 24 h, 48 h, 72 h and 96 h after inoculation, showed that esterified oxylipins are mainly produced with 9-derivatives in higher concentrations (esterified forms of colnelenic acid, 9-hydroxy octadecatrienoic acid, 9-hydroperoxy octadecatrienoic acid). Oxylipin accumulation is undetectable 24 h after infection, slightly detectable after 48 h, reaching highest concentrations after 96 h. Cultivars show slightly different oxylipin profiles but the concentration of individual oxylipins differs markedly 96 h after infection. No correlation was found between P. infestans resistance levels and oxylipin synthesis rates or concentration. To assess local and systemic effects of colneleic acid application before P. infestans infection, Bintje cultivar was sprayed with colneleic acid 72 h before inoculation. Both application modes (local and systemic) resulted in lipoxygenase pathway activation without affecting the resistance level to the pathogen.
Oxalis tuberosa is a vegetatively propagated
tuber crop in the Andes. The peasants cultivate a gr... more Oxalis tuberosa is a vegetatively propagated tuber crop in the Andes. The peasants cultivate a great number of varieties for which genetic homogeneity has never been demonstrated. Morphological descriptors and ISSR markers were used to determine the intravarietal diversity and the influence of the mode of conservation ex-situ vs in-situ. Molecular markers revealed an intra-varietal genetic diversity attesting that oca varieties are not pure clones. The morphological analysis was congruent with the peasant classification, contrary to the molecular markers. The comparison between both conservation strategies revealed a larger intra-varietal diversity in in-situ conditions and a genetic divergence between plants. The traditional practices are likely to be responsible of the intra-varietal polymorphism since the oca is propagated almost exclusively vegetatively. At the conservation level, differences could be explained by the sampling methods. A more integrated approach between genebanks and in-situ conservation is recommended to maintain the genetic resources of the species.
molecular markers have been
used to investigate genetic diversity of oca
(Oxalis tuberosa Mol.), ... more molecular markers have been used to investigate genetic diversity of oca (Oxalis tuberosa Mol.), an Andean neglected tuber crop species. Sampling procedure allowed a preliminary study of the genetic diversity at the intra- and intervarietal levels. Twenty tuber lots conserved in situ in the microcentre of Candelaria and ex situ in the Toralapa Centre (Bolivia) were identified. Four ISSR primers amplified a total of 25 fragments of which 17 (68%) were polymorphic. These experiments show that the structure of oca varieties is mainly based upon vernacular names with a greater differentiation among tuber lots than within them, supporting agromorphological data. ISSR technique enlightened the existence of heterogeneous varieties in oca and divergence between in situ and ex situ conservation strategies. These observations are potentially linked to the different ways of management of tubers in these two conservation systems.
Quinoa (Chenopodium quinoaWilld.) is a widely consumed food crop and a primary protein source for... more Quinoa (Chenopodium quinoaWilld.) is a widely consumed food crop and a primary protein source for many of the indigenous inhabitants of the Andean region of South America. In this study, we report the development of immature seed and floral expressed sequenced tag (EST) libraries and the identification of single nucleotide polymorphisms (SNPs) for quinoa. A total of 424 cDNA clones derived from immature seed and floral tissue were sequenced and analyzed for homology with known gene sequences. Three hundred and eleven of the clones were identified as homologues of known plant proteins, 38 were homologous to Arabidopsis proteins with no known function and 75 do not share significant homology with any protein in the queried databases. Interestingly, several of the annotated ESTs were present in relatively high abundance and have putative functions related to plant defense. Based on EST sequence information, fragments of 34 ESTs were amplified and sequenced in five quinoa accessions and one related weed species, C. berlandieri. Analysis of the quinoa EST sequences revealed a total of 51 SNPs in 20 EST sequences, including 38 single-base changes and 13 insertions–deletions (indels), with an average 1 SNP per 462 base pairs (bp) and 1 indel per 1812 bp. When the C. berlandieri accession was included in the analysis, 29 of the EST clones screened had at least one SNP present and an additional 81 SNPs were identified, bringing the total number of SNPs discovered to 132 (1 per 179 bp). The EST clones and SNP markers identified in this manuscript are of particular value in ongoing efforts to characterize gene expression and regulation associated with seed development, while the SNPs identified have immediate application for genetic mapping experiments, germplasm development, and the investigation of evolutionary relationships within the genus Chenopodium. # 2004 Elsevier Ireland Ltd. All rights reserved.
The nucleolus organizer region (NOR) and 5S ribosomal RNA (rRNA) genes are valuable as chromosome... more The nucleolus organizer region (NOR) and 5S ribosomal RNA (rRNA) genes are valuable as chromosome landmarks and in evolutionary studies. The NOR intergenic spacers (IGS) and 5S rRNA nontranscribed spacers (NTS) were PCR-amplified and sequenced from 5 cultivars of the Andean grain crop quinoa (Chenopodium quinoa Willd., 2n = 4x = 36) and a related wild ancestor (C. berlandieri Moq. subsp. zschackei (Murr) A. Zobel, 2n = 4x = 36). Length heterogeneity observed in the IGS resulted from copy number difference in subrepeat elements, small rearrangements , and species-specific indels, though the general sequence composition of the 2 species was highly similar. Fifteen of the 41 sequence polymorphisms identified among the C. quinoa lines were synapomorphic and clearly differentiated the highland and lowland ecotypes. Analysis of the NTS sequences revealed 2 basic NTS sequence classes that likely originated from the 2 allopolyploid subgenomes of C. quinoa. Fluorescence in situ hybridization (FISH) analysis showed that C. quinoa possesses an interstitial and a terminal pair of 5S rRNA loci and only 1 pair of NOR, suggesting a reduction in the number of rRNA loci during the evolution of this species. C. berlandieri exhibited variation in both NOR and 5S rRNA loci without changes in ploidy. Résumé : L'organisateur nucléolaire (NOR) et les gènes codant pour les ARN ribosomiques 5S sont utiles comme re-pères chromosomiques et pour des études sur l'évolution. Les espaceurs intergéniques (IGS) des NOR et les espaceurs non-transcrits (NTS) des ARNr 5S ont été amplifiés et séquencés chez 5 cultivars du quinoa (Chenopodium quinoa Willd., 2n = 4x = 36), une pseudocéréale des Andes, et un ancêtre sauvage (C. berlandieri Moq. subsp. Zschakei (Murr) A. Zobel, 2n = 4x = 36). Une hétérogénéité de taille a été observée chez les IGS en raison d'une différence quant au nombre de copies des sous-répétitions, de petits réarrangements et d'indels spécifiques d'une espèce. En géné-ral, cependant, la composition des séquences était très semblable entre les 2 espèces. Quinze des 41 polymorphismes identifiés au sein des lignées de C. quinoa étaient synapomorphes et distinguaient clairement les écotypes des bas-fonds de ceux de montagne. Une analyse des séquences NTS a révélé 2 classes de séquences NTS qui dérivent vrai-semblablement des 2 sous-génomes allopolyploïdes du C. quinoa. Une hybridation in situ en fluorescence (FISH) a montré que le C. quinoa possède 2 paires de locus d'ARNr 5S, l'une terminal et l'autre interne, mais 1 seule paire de locus NOR, ce qui suggère une réduction du nombre de locus d'ARNr au cours de l'évolution de cette espèce. Le C. berlandieri montrait une variation au niveau des locus NOR et d'ARNr 5S sans qu'il y ait de changement de ploïdie.
Resumen. Las especies silvestres de tomate presentan genes que podrían elevar la calidad de los c... more Resumen. Las especies silvestres de tomate presentan genes que podrían elevar la calidad de los cultivos y su valor nutricional. El objetivo del trabajo fue estudiar la di-versidad genética del tomate silvestre (Solanum spp.) a nivel morfológico y molecular a fin de diseñar estrategias de conservación y uso eficiente de genes de interés agro-nómico. Se analizó, a nivel morfológico, características de la planta, flor y fruto. Para el análisis molecular, se utilizó tejido de hoja para la extracción de ADN. Se realizó un análisis de componentes principales y la construcción de un clúster con datos morfo-lógicos. Estos análisis generaron un grupo formado por especies silvestres var. ceraci-forme repatriadas del Centro de Recursos Genéticos de Tomate (TGRC) y las silves-tres colectadas en Bolivia S. neorickii (código CPL), el otro grupo, formado por varie-dades ceraciformes (código CL) y una cultivada colectada en Bolivia. El análisis molecular confirmó la formación de dos grupos con mayor claridad, un grupo formado por accesiones colectadas denominadas S. neorickii (código CPL) más relacionadas con S. chmielewskii, el segundo grupo formado por las especies S. lycopersicum var. ce-raciforme. Las accesiones clasificadas como S. neorickii están más relacionadas a la especie S. chmielewski, pudiéndose concluir que podrían pertenecer a esta ultima especie. Abstract. Morphological and molecular study of genetic diversity of bolivian wild tomato (Solanum spp.) Wild tomato species have genes that could improve the quality of crops and their nutritional value. The objective was to study the genetic diversity of wild tomato (Solanum spp.) to morphological and molecular level in order to devise strategies for the conservation and efficient use of genes of agronomic interest. For this was analyzed morphologically characteristics of the plant, flower and fruit. For the molecular analysis of leaf tissue for DNA extraction was used. Principal component analysis and the construction of a cluster with morphological data were performed. These analyzes generated two groups: the first group of wild species var. ceraciforme repatriated from Tomato Genetics Resource Center (TGRC) and wild S. neorickii collected in Bolivia (CPL code), the second group, consisting ceraciformes varieties (CL code) and cultivated collected in Bolivia. Molecular analysis confirmed the formation of two groups more clearly: a group of accessions collected called S. neorickii (CPL code) more related to S. chmielewskii, the second group consists of the species S. lycopersi-cum var. ceraciforme. Accessions classified as S. neorickii are more related to the species S. Chmielewski, it can be concluded that belong to the latter species.
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Papers by Jorge Antonio Rojas-Beltrán
La quinua fue domesticada en Bolivia, en inmediaciones del lago Titicaca (Gandarillas, 1986) hace mas o menos 6000 años atrás. Desde este centro de domesticación, su cultivo se ha extendido por toda la cordillera de los Andes. Actualmente la quinua se cultiva en Argentina, Chile, Bolivia, Perú, Ecuador y Colombia, siendo Bolivia el principal país productor. Se la cultiva desde el nivel del mar hasta los 4,000 m. Su período de crecimiento varía entre 90 y 220 días, dependiendo de las variedades. Produce aproximadamente entre 1 y 5 t/ha de semillas.
En Bolivia la quinua se produce principalmente en el altiplano y de forma marginal en los valles interandinos. Desde el punto de vista agro-ecológico, el altiplano boliviano puede ser dividido en tres regiones: Altiplano Norte, Centro, y Sur. En el Altiplano Norte, el sistema productivo esta basado en el cultivo de papa, quinua, cebada y avena. La producción de papa y quinua está destinada principalmente al consumo familiar. El principal factor limitante para la producción de quinua en esta región es la enfermedad del mildeu (Peronosproa farinosa) que puede reducir los rendimientos hasta en un 99% (Danielsen et al., 2000). Otro factor que desalienta la producción de quinua en esta zona es la baja calidad del grano de las variedades nativas (tamaño pequeño del grano que no es apreciado en el mercado de exportación).
En el Altiplano Central el sistema de producción está basado en la rotación de cultivos de papa, quinua y forrajeras. Las variedades de quinua cultivadas en esta zona son de ciclo semi-tardío y tardío, de grano pequeño a mediano. La quinua representa el 30% del ingreso anual del agricultor. Los principales factores limitantes de la producción de quinua en esta región son las enfermedades fungosas (mildiú) y las plagas. Entre las plagas se tienen a los gusanos cortadores o “ticonas” (Feltia spp., Agrotis spp. y Spodoptera spp.), y “kona-konas” que son larvas de la polilla de la quinua (Eurysacca quinoae).
En el Altiplano Sur las condiciones climáticas son extremas, la región es muy árida (precipitación anual promedio de 200 mm), con alto riesgo de heladas. Los suelos son generalmente arenosos, de baja fertilidad y afectados por la salinidad. En algunos casos, un período prolongado de sequía puede ocasionar la pérdida total del cultivo. La quinua es el único cultivo capaz de tolerar satisfactoriamente estas condiciones climáticas. Aparte de su importancia en la dieta diaria de la población del Altiplano Sur, la quinua es una fuente importante de ingresos para los pobladores, representando cerca de la mitad de su ingreso anual. Actualmente existen numerosas empresas y organización de productores que se dedican al beneficiado y comercialización de la quinua. El 60% de la producción de quinua de esta región es destinada a mercados domésticos y de exportación.
La colección Boliviana de quinua cuenta en la actualidad con más 3000 accesiones, siendo la más grande del mundo, la misma que se conserva en la estación experimental de Quipa-Quipani (La Paz). Las accesiones provienen del Altiplano Sur, Centro y Norte, de los valles interandinos. Adicionalmente se cuenta con accesiones del Norte Peruano, de Argentina y Chile, y una colección internacional. Esta colección ha sido caracterizada morfológicamente y evaluada para numerosos caracteres de interés agronómico y económico.
Si bien existe la creencia generalizada de que en los bancos de germoplasma se encuentran genes útiles para mejorar los cultivos, la realidad muestra que los científicos no han tenido mucho éxito en identificar e incorporar esos genes a cultivos comerciales (Tanksley y McCouch, 1997). La mayoría de las accesiones de los bancos de germoplasma no han contribuido, en la medida que se espera, a las variedades modernas, particularmente en lo que respecta a los caracteres complejos, como son el rendimiento, la calidad, etc. Esto se debe en gran parte a que la caracterización y utilización del germoplasma ha estado exclusivamente basado en la búsqueda del fenotipo apropiado. Sin embargo, existen evidencias que demuestran que la diversidad genética almacenada en los bancos de germoplasma puede ser aprovechada con una eficiencia nunca antes imaginada, si no se toma en cuenta a priori el fenotipo apropiado como criterio de elección. Así por ejemplo, se ha comprobado, mediante técnicas moleculares, que en arroces de bajo rendimiento existen genes para aumentar el rendimiento (Xiao et al. 1996).
En consecuencia, es importante complementar las caracterizaciones y evaluaciones fenotípicas con estudios similares a nivel molecular, para un mejor aprovechamiento del germoplasma conservado. En esta perspectiva, mediante esta actividad, se ha caracterizado molecularmente más de 2500 accesiones de quinua.
Aellen) is a poorly studied, annual subsistence crop
of the high Andes of South America. Its nutritional
value (high in protein and mineral content) and
ability to thrive in harsh climates make it an
important regional food crop throughout the Andean
region. The objectives of this study were to develop
genetic markers and to quantify genetic diversity
within can˜ahua. A set of 43 wild and cultivated
can˜ahua genotypes and two related species (Chenopodium
quinoa Willd. and Chenopodium petiolare
Kunth) were evaluated for polymorphism using 192
microsatellite markers derived from random genomic
can˜ahua sequences produced by 454 pyrosequencing
of can˜ahua genomic DNA. Another 424 microsatellite
markers from C. quinoa were also evaluated for
cross-species amplification and polymorphism in
can˜ahua. A total of 34 polymorphic microsatellite
marker loci were identified which detected a total of 154 alleles with an average of 4.5 alleles per marker
locus and an average heterozygosity value of 0.49. A
cluster analysis, based on Nei genetic distance,
clearly separated from wild can˜ahua genotypes from
the cultivated genotypes. Within the cultivated
genotypes, subclades were partitioned by AMOVA
analysis into six model-based clusters, including a
subclade consisting sole of erect morphotypes. The
isolation by distance test displayed no significant
correlation between geographic collection origin and
genotypic data, suggesting that can˜ahua populations
have moved extensively, presumably via ancient food
exchange strategies among native peoples of the
Andean region. The molecular markers reported here
are a significant resource for ongoing efforts to
characterize the extensive Bolivian and Peruvian
can˜ahua germplasm banks, including the development
of core germplasm collections needed to
support emerging breeding programs.
tuber crop in the Andes. The peasants cultivate a great
number of varieties for which genetic homogeneity has
never been demonstrated. Morphological descriptors
and ISSR markers were used to determine the intravarietal
diversity and the influence of the mode of
conservation ex-situ vs in-situ. Molecular markers
revealed an intra-varietal genetic diversity attesting
that oca varieties are not pure clones. The morphological
analysis was congruent with the peasant classification,
contrary to the molecular markers. The
comparison between both conservation strategies
revealed a larger intra-varietal diversity in in-situ
conditions and a genetic divergence between plants.
The traditional practices are likely to be responsible of
the intra-varietal polymorphism since the oca is propagated
almost exclusively vegetatively. At the conservation
level, differences could be explained by
the sampling methods. A more integrated approach
between genebanks and in-situ conservation is recommended
to maintain the genetic resources of the species.
used to investigate genetic diversity of oca
(Oxalis tuberosa Mol.), an Andean neglected
tuber crop species. Sampling procedure allowed a
preliminary study of the genetic diversity at the
intra- and intervarietal levels. Twenty tuber lots
conserved in situ in the microcentre of Candelaria
and ex situ in the Toralapa Centre (Bolivia) were
identified. Four ISSR primers amplified a total of
25 fragments of which 17 (68%) were polymorphic.
These experiments show that the structure
of oca varieties is mainly based upon vernacular
names with a greater differentiation among tuber
lots than within them, supporting agromorphological
data. ISSR technique enlightened the
existence of heterogeneous varieties in oca and divergence between in situ and ex situ conservation
strategies. These observations are potentially
linked to the different ways of management of
tubers in these two conservation systems.
of the Andean region of South America. In this study, we report the development of immature seed and floral expressed sequenced tag (EST)
libraries and the identification of single nucleotide polymorphisms (SNPs) for quinoa. A total of 424 cDNA clones derived from immature
seed and floral tissue were sequenced and analyzed for homology with known gene sequences. Three hundred and eleven of the clones were
identified as homologues of known plant proteins, 38 were homologous to Arabidopsis proteins with no known function and 75 do not share
significant homology with any protein in the queried databases. Interestingly, several of the annotated ESTs were present in relatively high
abundance and have putative functions related to plant defense. Based on EST sequence information, fragments of 34 ESTs were amplified
and sequenced in five quinoa accessions and one related weed species, C. berlandieri. Analysis of the quinoa EST sequences revealed a total
of 51 SNPs in 20 EST sequences, including 38 single-base changes and 13 insertions–deletions (indels), with an average 1 SNP per 462 base
pairs (bp) and 1 indel per 1812 bp. When the C. berlandieri accession was included in the analysis, 29 of the EST clones screened had at least
one SNP present and an additional 81 SNPs were identified, bringing the total number of SNPs discovered to 132 (1 per 179 bp). The EST
clones and SNP markers identified in this manuscript are of particular value in ongoing efforts to characterize gene expression and regulation
associated with seed development, while the SNPs identified have immediate application for genetic mapping experiments, germplasm
development, and the investigation of evolutionary relationships within the genus Chenopodium.
# 2004 Elsevier Ireland Ltd. All rights reserved.
postulated as a protein that primes starch biosynthesis. Polyclonal antibodies raised against UPTG purified from potato (Solanum
tuberosum L.) tubers were used to screen a potato swelling stolon tip cDNA expression library. The isolation, cloning and
sequencing of two cDNAs corresponding to UPTG are described. Recombinant UPTG was labelled after incubation with
UDP-[14C]-Glc and Mn2+, indicating that it was enzymatically active. It was determined that purified as well as recombinant
UPTG can be reversibly glycosylated by UDP-Glc, UDP-Xyl or UDP-Gal. RNA hybridization studies and western blot analysis
indicate that UPTG mRNA and protein are expressed in all potato tissues. Databank searches revealed a high degree of identity
between UPTG and several plant sequences that encode for proteins with apparent localization at the cytoplasmic face of the
Golgi apparatus and at plasmodesmata. The biochemical properties of UPTG and the apparent lack of a signal peptide that could
allow its entrance into plastids argue against the postulated role of UPTG in starch synthesis and point towards a possible role
of the protein in the synthesis of cell wall polysaccharides. © 1999 Éditions scientifiques et médicales Elsevier SAS
La quinua fue domesticada en Bolivia, en inmediaciones del lago Titicaca (Gandarillas, 1986) hace mas o menos 6000 años atrás. Desde este centro de domesticación, su cultivo se ha extendido por toda la cordillera de los Andes. Actualmente la quinua se cultiva en Argentina, Chile, Bolivia, Perú, Ecuador y Colombia, siendo Bolivia el principal país productor. Se la cultiva desde el nivel del mar hasta los 4,000 m. Su período de crecimiento varía entre 90 y 220 días, dependiendo de las variedades. Produce aproximadamente entre 1 y 5 t/ha de semillas.
En Bolivia la quinua se produce principalmente en el altiplano y de forma marginal en los valles interandinos. Desde el punto de vista agro-ecológico, el altiplano boliviano puede ser dividido en tres regiones: Altiplano Norte, Centro, y Sur. En el Altiplano Norte, el sistema productivo esta basado en el cultivo de papa, quinua, cebada y avena. La producción de papa y quinua está destinada principalmente al consumo familiar. El principal factor limitante para la producción de quinua en esta región es la enfermedad del mildeu (Peronosproa farinosa) que puede reducir los rendimientos hasta en un 99% (Danielsen et al., 2000). Otro factor que desalienta la producción de quinua en esta zona es la baja calidad del grano de las variedades nativas (tamaño pequeño del grano que no es apreciado en el mercado de exportación).
En el Altiplano Central el sistema de producción está basado en la rotación de cultivos de papa, quinua y forrajeras. Las variedades de quinua cultivadas en esta zona son de ciclo semi-tardío y tardío, de grano pequeño a mediano. La quinua representa el 30% del ingreso anual del agricultor. Los principales factores limitantes de la producción de quinua en esta región son las enfermedades fungosas (mildiú) y las plagas. Entre las plagas se tienen a los gusanos cortadores o “ticonas” (Feltia spp., Agrotis spp. y Spodoptera spp.), y “kona-konas” que son larvas de la polilla de la quinua (Eurysacca quinoae).
En el Altiplano Sur las condiciones climáticas son extremas, la región es muy árida (precipitación anual promedio de 200 mm), con alto riesgo de heladas. Los suelos son generalmente arenosos, de baja fertilidad y afectados por la salinidad. En algunos casos, un período prolongado de sequía puede ocasionar la pérdida total del cultivo. La quinua es el único cultivo capaz de tolerar satisfactoriamente estas condiciones climáticas. Aparte de su importancia en la dieta diaria de la población del Altiplano Sur, la quinua es una fuente importante de ingresos para los pobladores, representando cerca de la mitad de su ingreso anual. Actualmente existen numerosas empresas y organización de productores que se dedican al beneficiado y comercialización de la quinua. El 60% de la producción de quinua de esta región es destinada a mercados domésticos y de exportación.
La colección Boliviana de quinua cuenta en la actualidad con más 3000 accesiones, siendo la más grande del mundo, la misma que se conserva en la estación experimental de Quipa-Quipani (La Paz). Las accesiones provienen del Altiplano Sur, Centro y Norte, de los valles interandinos. Adicionalmente se cuenta con accesiones del Norte Peruano, de Argentina y Chile, y una colección internacional. Esta colección ha sido caracterizada morfológicamente y evaluada para numerosos caracteres de interés agronómico y económico.
Si bien existe la creencia generalizada de que en los bancos de germoplasma se encuentran genes útiles para mejorar los cultivos, la realidad muestra que los científicos no han tenido mucho éxito en identificar e incorporar esos genes a cultivos comerciales (Tanksley y McCouch, 1997). La mayoría de las accesiones de los bancos de germoplasma no han contribuido, en la medida que se espera, a las variedades modernas, particularmente en lo que respecta a los caracteres complejos, como son el rendimiento, la calidad, etc. Esto se debe en gran parte a que la caracterización y utilización del germoplasma ha estado exclusivamente basado en la búsqueda del fenotipo apropiado. Sin embargo, existen evidencias que demuestran que la diversidad genética almacenada en los bancos de germoplasma puede ser aprovechada con una eficiencia nunca antes imaginada, si no se toma en cuenta a priori el fenotipo apropiado como criterio de elección. Así por ejemplo, se ha comprobado, mediante técnicas moleculares, que en arroces de bajo rendimiento existen genes para aumentar el rendimiento (Xiao et al. 1996).
En consecuencia, es importante complementar las caracterizaciones y evaluaciones fenotípicas con estudios similares a nivel molecular, para un mejor aprovechamiento del germoplasma conservado. En esta perspectiva, mediante esta actividad, se ha caracterizado molecularmente más de 2500 accesiones de quinua.
Aellen) is a poorly studied, annual subsistence crop
of the high Andes of South America. Its nutritional
value (high in protein and mineral content) and
ability to thrive in harsh climates make it an
important regional food crop throughout the Andean
region. The objectives of this study were to develop
genetic markers and to quantify genetic diversity
within can˜ahua. A set of 43 wild and cultivated
can˜ahua genotypes and two related species (Chenopodium
quinoa Willd. and Chenopodium petiolare
Kunth) were evaluated for polymorphism using 192
microsatellite markers derived from random genomic
can˜ahua sequences produced by 454 pyrosequencing
of can˜ahua genomic DNA. Another 424 microsatellite
markers from C. quinoa were also evaluated for
cross-species amplification and polymorphism in
can˜ahua. A total of 34 polymorphic microsatellite
marker loci were identified which detected a total of 154 alleles with an average of 4.5 alleles per marker
locus and an average heterozygosity value of 0.49. A
cluster analysis, based on Nei genetic distance,
clearly separated from wild can˜ahua genotypes from
the cultivated genotypes. Within the cultivated
genotypes, subclades were partitioned by AMOVA
analysis into six model-based clusters, including a
subclade consisting sole of erect morphotypes. The
isolation by distance test displayed no significant
correlation between geographic collection origin and
genotypic data, suggesting that can˜ahua populations
have moved extensively, presumably via ancient food
exchange strategies among native peoples of the
Andean region. The molecular markers reported here
are a significant resource for ongoing efforts to
characterize the extensive Bolivian and Peruvian
can˜ahua germplasm banks, including the development
of core germplasm collections needed to
support emerging breeding programs.
tuber crop in the Andes. The peasants cultivate a great
number of varieties for which genetic homogeneity has
never been demonstrated. Morphological descriptors
and ISSR markers were used to determine the intravarietal
diversity and the influence of the mode of
conservation ex-situ vs in-situ. Molecular markers
revealed an intra-varietal genetic diversity attesting
that oca varieties are not pure clones. The morphological
analysis was congruent with the peasant classification,
contrary to the molecular markers. The
comparison between both conservation strategies
revealed a larger intra-varietal diversity in in-situ
conditions and a genetic divergence between plants.
The traditional practices are likely to be responsible of
the intra-varietal polymorphism since the oca is propagated
almost exclusively vegetatively. At the conservation
level, differences could be explained by
the sampling methods. A more integrated approach
between genebanks and in-situ conservation is recommended
to maintain the genetic resources of the species.
used to investigate genetic diversity of oca
(Oxalis tuberosa Mol.), an Andean neglected
tuber crop species. Sampling procedure allowed a
preliminary study of the genetic diversity at the
intra- and intervarietal levels. Twenty tuber lots
conserved in situ in the microcentre of Candelaria
and ex situ in the Toralapa Centre (Bolivia) were
identified. Four ISSR primers amplified a total of
25 fragments of which 17 (68%) were polymorphic.
These experiments show that the structure
of oca varieties is mainly based upon vernacular
names with a greater differentiation among tuber
lots than within them, supporting agromorphological
data. ISSR technique enlightened the
existence of heterogeneous varieties in oca and divergence between in situ and ex situ conservation
strategies. These observations are potentially
linked to the different ways of management of
tubers in these two conservation systems.
of the Andean region of South America. In this study, we report the development of immature seed and floral expressed sequenced tag (EST)
libraries and the identification of single nucleotide polymorphisms (SNPs) for quinoa. A total of 424 cDNA clones derived from immature
seed and floral tissue were sequenced and analyzed for homology with known gene sequences. Three hundred and eleven of the clones were
identified as homologues of known plant proteins, 38 were homologous to Arabidopsis proteins with no known function and 75 do not share
significant homology with any protein in the queried databases. Interestingly, several of the annotated ESTs were present in relatively high
abundance and have putative functions related to plant defense. Based on EST sequence information, fragments of 34 ESTs were amplified
and sequenced in five quinoa accessions and one related weed species, C. berlandieri. Analysis of the quinoa EST sequences revealed a total
of 51 SNPs in 20 EST sequences, including 38 single-base changes and 13 insertions–deletions (indels), with an average 1 SNP per 462 base
pairs (bp) and 1 indel per 1812 bp. When the C. berlandieri accession was included in the analysis, 29 of the EST clones screened had at least
one SNP present and an additional 81 SNPs were identified, bringing the total number of SNPs discovered to 132 (1 per 179 bp). The EST
clones and SNP markers identified in this manuscript are of particular value in ongoing efforts to characterize gene expression and regulation
associated with seed development, while the SNPs identified have immediate application for genetic mapping experiments, germplasm
development, and the investigation of evolutionary relationships within the genus Chenopodium.
# 2004 Elsevier Ireland Ltd. All rights reserved.
postulated as a protein that primes starch biosynthesis. Polyclonal antibodies raised against UPTG purified from potato (Solanum
tuberosum L.) tubers were used to screen a potato swelling stolon tip cDNA expression library. The isolation, cloning and
sequencing of two cDNAs corresponding to UPTG are described. Recombinant UPTG was labelled after incubation with
UDP-[14C]-Glc and Mn2+, indicating that it was enzymatically active. It was determined that purified as well as recombinant
UPTG can be reversibly glycosylated by UDP-Glc, UDP-Xyl or UDP-Gal. RNA hybridization studies and western blot analysis
indicate that UPTG mRNA and protein are expressed in all potato tissues. Databank searches revealed a high degree of identity
between UPTG and several plant sequences that encode for proteins with apparent localization at the cytoplasmic face of the
Golgi apparatus and at plasmodesmata. The biochemical properties of UPTG and the apparent lack of a signal peptide that could
allow its entrance into plastids argue against the postulated role of UPTG in starch synthesis and point towards a possible role
of the protein in the synthesis of cell wall polysaccharides. © 1999 Éditions scientifiques et médicales Elsevier SAS