Moniliophthora roreri is the fungal pathogen that causes frosty pod rot (FPR) disease of Theobrom... more Moniliophthora roreri is the fungal pathogen that causes frosty pod rot (FPR) disease of Theobroma cacao L., the source of chocolate. FPR occurs in most of the cacao producing countries in the Western Hemisphere, causing yield losses up to 80%. Genetic diversity within the FPR pathogen population may allow the population to adapt to changing environmental conditions and adapt to enhanced resistance in the host plant. The present study developed single nucleotide polymorphism (SNP) markers from RNASeq results for 13 M. roreri isolates and validated the markers for their ability to reveal genetic diversity in an international M. roreri collection. The SNP resources reported herein represent the first study of RNA sequencing (RNASeq)-derived SNP validation in M. roreri and demonstrates the utility of RNASeq as an approach for de novo SNP identification in M. roreri. A total of 88 polymorphic SNPs were used to evaluate the genetic diversity of 172 M. roreri cacao isolates resulting in 37 distinct genotypes (including 14 synonymous groups). Absence of heterozygosity for the 88 SNP markers indicates reproduction in M. roreri is clonal and likely due to a homothallic life style. The upper Magdalena Valley of Colombia showed the highest levels of genetic diversity with 20 distinct genotypes of which 13 were limited to this region, and indicates this region as the possible center of origin for M. roreri.
Drought can negatively impact pod production despite the fact that cacao production usually occur... more Drought can negatively impact pod production despite the fact that cacao production usually occurs in tropical areas having high rainfall. Polyamines (PAs) have been associated with the response of plants to drought in addition to their roles in responses to many other stresses. The constitutive and drought inducible expression patterns of genes encoding enzymes involved in PA biosynthesis were determined:
A chimeric octopine synthase-neomycin phosphotransferase (ocs-nptII) gene was used to transform C... more A chimeric octopine synthase-neomycin phosphotransferase (ocs-nptII) gene was used to transform Chlamydomonas reinhardiii to kanamycin resistance. Southern hybridization using DNA isolated from one transformant, T6.1, indicated that the entire ocs-nptII gene and at least part of the plasmid were integrated into nuclear DNA. Neomycin phosphotransferase II activity has been detected in T6.1 cell extracts. Northern hybridizations, employing a radiolabeled ocs-nptII sequence, revealed a T6.1 transcript of approximately the same size as a homologous transcript isolated from E. coli carrying the nptII gene. Although T6.1 is an extremely rare example of a stable C. reinhardtii transformant, its occurrence nevertheless indicates that bacterial genes can be expressed in the nucleus of the alga.
... the perceived effectiveness of a mycoherbicide undoubtedly differ depending on the cropping s... more ... the perceived effectiveness of a mycoherbicide undoubtedly differ depending on the cropping system being used. ... of EN-4 in all four soil types tested (Table 1). Although variable, populations of EN ... of EN-4 in the soil in both Ūeld experiments, and this treatment effect also varied ...
In order to deregulate arginine biosynthesis in Synechococcus sp. PCC7942, d-arginine-resistant c... more In order to deregulate arginine biosynthesis in Synechococcus sp. PCC7942, d-arginine-resistant cell lines were selected following ethyl methanesulfonate mutagenesis of wild-type (WT) cells. Three of these arginine-producing mutant (APM) cell lines, APM1, APM31 and APM40, were putative regulatory mutants based upon secretion of l-arginine into their growth medium. HPLC of lyophilized post-harvest supernatants of APM 31 and 40 resolved two
Trichoderma species are usually considered soil organisms that colonize plant roots, sometimes fo... more Trichoderma species are usually considered soil organisms that colonize plant roots, sometimes forming a symbiotic relationship. Recent studies demonstrate that Trichoderma species are also capable of colonizing the above ground tissues of Theobroma cacao (cacao) in what has been characterized as an endophytic relationship. Trichoderma species can be re-isolated from surface sterilized cacao stem tissue, including the bark and xylem, the apical meristem, and to a lesser degree from leaves. SEM analysis of cacao stems colonized by strains of four Trichoderma species (Trichoderma ovalisporum-DIS 70a, Trichoderma hamatum-DIS 219b, Trichoderma koningiopsis-DIS 172ai, or Trichoderma harzianum-DIS 219f) showed a preference for surface colonization of glandular trichomes versus non-glandular trichomes. The Trichoderma strains colonized the glandular trichome tips and formed swellings resembling appresoria. Hyphae were observed emerging from the glandular trichomes on surface sterilized ste...
Moniliophthora roreri is the fungal pathogen that causes frosty pod rot (FPR) disease of Theobrom... more Moniliophthora roreri is the fungal pathogen that causes frosty pod rot (FPR) disease of Theobroma cacao L., the source of chocolate. FPR occurs in most of the cacao producing countries in the Western Hemisphere, causing yield losses up to 80%. Genetic diversity within the FPR pathogen population may allow the population to adapt to changing environmental conditions and adapt to enhanced resistance in the host plant. The present study developed single nucleotide polymorphism (SNP) markers from RNASeq results for 13 M. roreri isolates and validated the markers for their ability to reveal genetic diversity in an international M. roreri collection. The SNP resources reported herein represent the first study of RNA sequencing (RNASeq)-derived SNP validation in M. roreri and demonstrates the utility of RNASeq as an approach for de novo SNP identification in M. roreri. A total of 88 polymorphic SNPs were used to evaluate the genetic diversity of 172 M. roreri cacao isolates resulting in 37 distinct genotypes (including 14 synonymous groups). Absence of heterozygosity for the 88 SNP markers indicates reproduction in M. roreri is clonal and likely due to a homothallic life style. The upper Magdalena Valley of Colombia showed the highest levels of genetic diversity with 20 distinct genotypes of which 13 were limited to this region, and indicates this region as the possible center of origin for M. roreri.
Drought can negatively impact pod production despite the fact that cacao production usually occur... more Drought can negatively impact pod production despite the fact that cacao production usually occurs in tropical areas having high rainfall. Polyamines (PAs) have been associated with the response of plants to drought in addition to their roles in responses to many other stresses. The constitutive and drought inducible expression patterns of genes encoding enzymes involved in PA biosynthesis were determined:
A chimeric octopine synthase-neomycin phosphotransferase (ocs-nptII) gene was used to transform C... more A chimeric octopine synthase-neomycin phosphotransferase (ocs-nptII) gene was used to transform Chlamydomonas reinhardiii to kanamycin resistance. Southern hybridization using DNA isolated from one transformant, T6.1, indicated that the entire ocs-nptII gene and at least part of the plasmid were integrated into nuclear DNA. Neomycin phosphotransferase II activity has been detected in T6.1 cell extracts. Northern hybridizations, employing a radiolabeled ocs-nptII sequence, revealed a T6.1 transcript of approximately the same size as a homologous transcript isolated from E. coli carrying the nptII gene. Although T6.1 is an extremely rare example of a stable C. reinhardtii transformant, its occurrence nevertheless indicates that bacterial genes can be expressed in the nucleus of the alga.
... the perceived effectiveness of a mycoherbicide undoubtedly differ depending on the cropping s... more ... the perceived effectiveness of a mycoherbicide undoubtedly differ depending on the cropping system being used. ... of EN-4 in all four soil types tested (Table 1). Although variable, populations of EN ... of EN-4 in the soil in both Ūeld experiments, and this treatment effect also varied ...
In order to deregulate arginine biosynthesis in Synechococcus sp. PCC7942, d-arginine-resistant c... more In order to deregulate arginine biosynthesis in Synechococcus sp. PCC7942, d-arginine-resistant cell lines were selected following ethyl methanesulfonate mutagenesis of wild-type (WT) cells. Three of these arginine-producing mutant (APM) cell lines, APM1, APM31 and APM40, were putative regulatory mutants based upon secretion of l-arginine into their growth medium. HPLC of lyophilized post-harvest supernatants of APM 31 and 40 resolved two
Trichoderma species are usually considered soil organisms that colonize plant roots, sometimes fo... more Trichoderma species are usually considered soil organisms that colonize plant roots, sometimes forming a symbiotic relationship. Recent studies demonstrate that Trichoderma species are also capable of colonizing the above ground tissues of Theobroma cacao (cacao) in what has been characterized as an endophytic relationship. Trichoderma species can be re-isolated from surface sterilized cacao stem tissue, including the bark and xylem, the apical meristem, and to a lesser degree from leaves. SEM analysis of cacao stems colonized by strains of four Trichoderma species (Trichoderma ovalisporum-DIS 70a, Trichoderma hamatum-DIS 219b, Trichoderma koningiopsis-DIS 172ai, or Trichoderma harzianum-DIS 219f) showed a preference for surface colonization of glandular trichomes versus non-glandular trichomes. The Trichoderma strains colonized the glandular trichome tips and formed swellings resembling appresoria. Hyphae were observed emerging from the glandular trichomes on surface sterilized ste...
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