- Visiting address: Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands
Mail address: PO box 16, 6700AA Wageningen, The Netherlands - +31 317 480 833
Steven P.C. Groot
Wageningen University, Wageningen Plant Research, Department Member
- Wageningen University, Plant science group, Department Memberadd
- I’m a biologist studying the amazing world of seeds. I want to learn how seeds have evolved mechanisms to survive suc... moreI’m a biologist studying the amazing world of seeds. I want to learn how seeds have evolved mechanisms to survive such a long time, without ability for repair of oxidative damage in a dry condition. The results from our seed research is translated in practical applications for farmers, genebanks and seed companies, who finance part of our research. In private life I’m a SCUBA diving instructor and enjoy with partner and friends the wonderful underwater world.edit
With the growing demand for baby-leaf spinach (Spinacia oleracea L.) and an increasing ban on chemical seed treatments, problems of damping-off diseases become more apparent. Pythium ultimum has been shown to be the most common... more
With the growing demand for baby-leaf spinach (Spinacia oleracea L.) and an increasing ban on chemical seed treatments, problems of damping-off diseases become more apparent. Pythium ultimum has been shown to be the most common damping-off pathogen of spinach. Previous studies showed a large variation in pre-emergence damping-off tolerance levels among seed lots of spinach cultivars, which did not correlate with the rate of seedling emergence. In this study, we analysed if individual seed vigor-related traits, such as seed size and maturity, can influence seed tolerance towards pre-emergence infection by P. ultimum. Seeds of the same seed lots were measured for their morphological and multispectral properties on the level of a single seed. The seedling emergence from those individual seeds was assessed at different P. ultimum doses and for each individual seed, the characteristics were correlated with its emergence success. The results showed that relatively higher levels of chlorophyll fluorescence, an indicator of lesser seed maturity, had a negative association with emergence success. With increasing P. ultimum dose, the seed size and light reflectance from the pericarp, particularly with violet-blue light, showed an increasingly negative association with emergence. This indicated that smaller seeds and seeds that reflected less (violet-blue) light were more tolerant towards P. ultimum infection. A validation study with seed size and maturity fractions of a single seed lot (excluding potential genotypic and seed production effects) confirmed that seed maturity had a positive association with seedling emergence, and that seed size had a negative association with the emergence in the presence of P. ultimum. Seed size and light reflectance accounted for a small part of the variation in P. ultimum tolerance among the seed lots. Selecting the most mature seeds with relatively less light reflectance (darker pericarp) or mature seeds with smaller sizes is recommended to obtain seed lots with improved pre-emergence damping-off tolerance levels.
Research Interests:
Seed deterioration during storage results in poor germination, reduced vigour, and non-uniform seedling emergence. The aging rate depends on storage conditions and genetic factors. This study aims to identify these genetic factors... more
Seed deterioration during storage results in poor germination, reduced vigour, and non-uniform seedling emergence. The aging rate depends on storage conditions and genetic factors. This study aims to identify these genetic factors determining the longevity of rice (Oryza sativa L.) seeds stored under experimental aging conditions mimicking long-term dry storage. Genetic variation for tolerance to aging was studied in 300 Indica rice accessions by storing dry seeds under an elevated partial pressure of oxygen (EPPO) condition. A genome-wide association analysis identified 11 unique genomic regions for all measured germination parameters after aging, differing from those previously identified in rice under humid experimental aging conditions. The significant single nucleotide polymorphism in the most prominent region was located within the Rc gene, encoding a basic helix-loop-helix transcription factor. Storage experiments using near-isogenic rice lines (SD7-1D (Rc) and SD7-1d (rc) with the same allelic variation confirmed the role of the wildtype Rc gene, providing stronger tolerance to dry EPPO aging. In the seed pericarp, a functional Rc gene results in accumulation of proanthocyanidins, an important sub-class of flavonoids having strong antioxidant activity, which may explain the variation in tolerance to dry EPPO aging.
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Genebanks aim to optimize their storage conditions in order to postpone seed ageing as long as possible. As most gene-banks have a relatively short life history, empirical data about seed longevity during ex situ storage are almost... more
Genebanks aim to optimize their storage conditions in order to postpone seed ageing as long as possible. As most gene-banks have a relatively short life history, empirical data about seed longevity during ex situ storage are almost absent. Based on seed characteristics, theoretical predictions indicate that cereal seeds can be stored without substantial loss of viability for time periods exceeding 100 years, even under temperatures of a few degrees above zero. Here we present the results of a germination study in wheat and barley, comparing genebank seed samples maintained at different temperatures for 23-33 years. Wheat and barley seed samples stored at −20°C showed a mean germination of 94% and 90%, respectively, indicating no loss of the initial viability determined for the accessions prior to introduction in the collection. Seed samples maintained at 4°C showed a mean germination of 62% for wheat and 75% for barley. In addition to the observed loss of viability, the 4°C samples also showed a loss in vigour as the time period to reach their final germination was about twice as long compared to the −20°C samples. A subset of the wheat accessions tested in 2011 were retested in 2017, showing further reduction in mean germination to 35% for the 4°C samples, while the −20°C samples remained stable at 95%. Several 4°C samples were even close to a complete loss of viability. Considering that wheat and barley are generally regarded as good maintainers, the rapid loss of seed viability observed in the present study indicates that the ex situ seed storage of genetic resources at 4°C should be treated with caution by genebanks, particularly when used for long-term conservation. Cite as: van Treuren R, Bas N, Kodde J, Groot SPC, Kik C (2018) Rapid loss of seed viability in ex situ conserved wheat and barley at 4°C as compared to −20°C storage. Conserv Physiol 6(1): coy033; doi:10.1093/conphys/coy033.
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Brassica oleracea plants can suffer from shoot apical meristem arrest, when sown at cold temperatures, giving rise to so-called blind seedlings that stop development and the formation of new leaves. We developed a seed treatment that... more
Brassica oleracea plants can suffer from shoot apical meristem arrest, when sown at cold temperatures, giving rise to so-called blind seedlings that stop development and the formation of new leaves. We developed a seed treatment that strongly reduces the occurrence of this meristem arrest in kohlrabi and cabbage seedlings. The developed treatment involves soaking the seeds in water for one hour at 22 °C before sowing at 0-2 °C. The reduction of susceptibility to induction of shoot apical meristem arrest could be maintained when seeds were dried after the pre-soaking treatment. A strong reduction in susceptibility could also be obtained by incubating the seeds for four hours with a limited amount of water to 20% moisture content. However, when the hydration was performed at seed moisture levels between 30 and 50%, the sensitivity to shoot apical meristem arrest was regained upon drying. The developed treatment to prevent the occurrence of shoot apical meristem arrest can easily be upscaled for implementation at the commercial level.
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Seed dormancy determines the timing of seed germination and may be released by dry storage, also referred to as after-ripening. Studies on dormancy-release mechanisms are often hampered by the long after-ripening requirements of seeds.... more
Seed dormancy determines the timing of seed germination and may be released by dry storage, also referred to as after-ripening. Studies on dormancy-release mechanisms are often hampered by the long after-ripening requirements of seeds. After-ripening is thought to be mainly caused by oxidative processes during seed dry storage. These processes are also the main cause of seed ageing. Increasing partial oxygen pressure through the elevated partial pressure of oxygen (EPPO) system has been shown to mimic and accelerate dry seed ageing. In this study, we investigated whether the EPPO system may also release primary seed dormancy in Arabidopsis thaliana. EPPO mimics dry after-ripening at the genetic level, as quantitative trait locus (QTL) analysis after EPPO treatment identified the DELAY OF GERMINATION loci DOG1, DOG2, and DOG6 that were first described in a study using dry after-ripening to release seed dormancy. QTL analysis also showed that dormancy release by cold stratification (another common method to break seed dormancy) partly overlaps with release by after-ripening and EPPO treatment. We conclude that EPPO is an appropriate method to mimic and accelerate dormancy release and, as such, may have applications in both research and industry.
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Plant genetic resources are conserved by genebanks mainly in the form of seeds. In most of the cases, the dried seeds can be stored for a considerable period of time, but eventually seed deterioration results in the inability to generate... more
Plant genetic resources are conserved by genebanks mainly in the form of seeds. In most of the cases, the dried seeds can be stored for a considerable period of time, but eventually seed deterioration results in the inability to generate healthy seedlings. Prolonging seed longevity during storage reduces the frequency of regeneration, which is beneficial from a genetic as well as a management point of view. To reduce the rate of deterioration, cool and dry storage conditions are usually practised for long-term seed storage. In spite of the growing body of evidence that seed deterioration is predominantly caused by oxidative processes, the importance of seed storage under anoxic conditions has received little attention from the genebank community. Herein, we report on the effects of anoxia on seed viability, the oxygen uptake by dry seeds in closed containers and the permeability for oxygen of various seed storage containers. Our results confirm that the ageing of dry seeds is accelerated by the presence of oxygen in the storage environment. Therefore, we recommend that genebanks store dry seeds under anoxic conditions to prolong their longevity during ex situ conservation. To reduce the initial rate of viability loss, we further recommend that the period of temporary storage after seed harvest be minimized and also that the seeds are kept during this period under controlled conditions, including anoxia.
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The seed industry in the Netherlands is the largest exporter of horticultural seeds, reaching farmers in every country of the world. High seed quality is one of the key factors of this success. Maintaining and increasing the level of seed... more
The seed industry in the Netherlands is the largest exporter of horticultural seeds, reaching farmers in
every country of the world. High seed quality is one of the
key factors of this success. Maintaining and increasing the level of seed quality requires skilled staff, innovation
and collaboration. Wageningen University & Research is supporting the seed industry in this.
every country of the world. High seed quality is one of the
key factors of this success. Maintaining and increasing the level of seed quality requires skilled staff, innovation
and collaboration. Wageningen University & Research is supporting the seed industry in this.
Research Interests:
Proteomics of Arabidopsis seeds revealed the differential accumulation during germination of two housekeeping enzymes. The first corresponded to methionine synthase that catalyses the last step in the plant methionine biosynthetic... more
Proteomics of Arabidopsis seeds revealed the differential accumulation during germination of two housekeeping enzymes. The first corresponded to methionine synthase that catalyses the last step in the plant methionine biosynthetic pathway. This protein was present at low level in dry mature seeds, and its level was increased strongly at 1-day imbibition, prior to radicle emergence. Its level was not increased further at 2-day imbibition, coincident with radicle emergence. However, its level in 1-day imbibed seeds strongly decreased upon subsequent drying of the imbibed seeds back to the original water content of the dry mature seeds. The second enzyme corresponded to S-adenosylmethionine synthetase that catalyses the synthesis of S-adenosylmethionine from methionine and ATP. In this case, this enzyme was detected in the form of two isozymes with different pI and Mr. Both proteins were absent in dry mature seeds and in 1-day imbibed seeds, but specifically accumulated at the moment of radicle protrusion. Arabidopsis seed germination was strongly delayed in the presence of propargylglycine, a specific inhibitor of methionine synthesis. Furthermore, this compound totally inhibited seedling growth. These phenotypic effects were largely alleviated upon methionine supplementation in the germination medium. The results indicated that methionine synthase and S-adenosylmethionine synthetase are fundamental components controlling metabolism in the transition from a quiescent to a highly active state during seed germination. Moreover, the observed temporal patterns of accumulation of these proteins are consistent with an essential role of endogenous ethylene in Arabidopsis only after radicle protrusion.
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To better understand seed germination, a complex developmental process, we developed a proteome analysis of the modelplant Arabidopsis for which complete genome sequence is now available. Among about 1,300 total seed proteins resolvedin... more
To better understand seed germination, a complex developmental process, we developed a proteome analysis of the modelplant Arabidopsis for which complete genome sequence is now available. Among about 1,300 total seed proteins resolvedin two-dimensional gels, changes in the abundance (up- and down-regulation) of 74 proteins were observed duringgermination sensu stricto (i.e. prior to radicle emergence) and the radicle protrusion step. This approach was also used to analyze protein changes occurring during industrial seed pretreatments such as priming that accelerate seed germinationand improve seedling uniformity. Several proteins were identified by matrix-assisted laser-desorption ionization time of flight mass spectrometry. Some of them had previously been shown to play a role during germination and/or priming inseveral plant species, a finding that underlines the usefulness of using Arabidopsis as a model system for molecular analysis of seed quality. Furthermore, the present study, carried out at the protein level, validates previous results obtained at the level of gene expression (e.g. from quantitation of differentially expressed mRNAs or analyses of promoter/reporter constructs). Finally, this approach revealed new proteins associated with the different phases of seed germination and priming. Some of them are involved either in the imbibition process of the seeds (such as an actin isoform or a WD-40 repeat protein) or in the seed dehydration process (e.g. cytosolic glyceraldehyde-3-phosphate dehydrogenase). These facts highlight the power of proteomics to unravel specific features of complex developmental processes such as germination and to detect protein markers that can be used to characterize seed vigor of commercial seed lots and to develop and monitor priming treatments.
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Cell cycle activity in dry and germinating untreated and treated (soaked in water and subsequently in fungicide)seeds of two sugarbeet cultivars, collected at commercialharvest time (late mature seeds) and about 2 weeks before this... more
Cell cycle activity in dry and germinating untreated and treated (soaked in water and subsequently in fungicide)seeds of two sugarbeet cultivars, collected at commercialharvest time (late mature seeds) and about 2 weeks before this (immature seeds), was investigated by flowcytometry, and by immuno-detection of
beta tubulin and the B-subunit of the 11S globulin. Germination capacity andfield emergence were tested. With dry seeds of bothcultivars, higher G2/G1 ratios were observed in the radicle tips of late mature seeds, as compared with those from immature seeds. The late mature seeds containedmore partly degraded (soluble) B-subunit of 11S globulin, typical of germinating or primed sugarbeet seeds. Thus events associated with the onset ofgermination had occurred in the seed lots collected atcommercial harvest time. The cytoskeleton protein beta-tubulin was not detectable in dry seeds from eitherharvest. Western blotting revealed an accumulation of beta-tubulin during germination and this was faster in the late mature harvested seeds which was correlated withthe onset of DNA replication. Soaking enhanced the rateof cell cycle activation during germination as well asvigour, germination capacity, and field emergence. There was positive correlation between the G2 /G1 ratio andthe traits examined in laboratory and field tests. It is concluded that a combined analysis of proteins and cell-cycle-related events can be used in understanding andpredicting sugarbeet seed quality.
beta tubulin and the B-subunit of the 11S globulin. Germination capacity andfield emergence were tested. With dry seeds of bothcultivars, higher G2/G1 ratios were observed in the radicle tips of late mature seeds, as compared with those from immature seeds. The late mature seeds containedmore partly degraded (soluble) B-subunit of 11S globulin, typical of germinating or primed sugarbeet seeds. Thus events associated with the onset ofgermination had occurred in the seed lots collected atcommercial harvest time. The cytoskeleton protein beta-tubulin was not detectable in dry seeds from eitherharvest. Western blotting revealed an accumulation of beta-tubulin during germination and this was faster in the late mature harvested seeds which was correlated withthe onset of DNA replication. Soaking enhanced the rateof cell cycle activation during germination as well asvigour, germination capacity, and field emergence. There was positive correlation between the G2 /G1 ratio andthe traits examined in laboratory and field tests. It is concluded that a combined analysis of proteins and cell-cycle-related events can be used in understanding andpredicting sugarbeet seed quality.
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Seed storage is often accompanied by a progressive loss of germination vigour and viabil-ity. In the present study, we have used Arabidopsis thaliana (L.) Heynh. seeds as a model, and carried out differential proteomics to investigate... more
Seed storage is often accompanied by a progressive loss of germination vigour and viabil-ity. In the present study, we have used
Arabidopsis thaliana
(L.) Heynh. seeds as a model, and carried out differential proteomics to investigate seed vigour. In our system, based on a controlled deterioration treatment (CDT), we compared seed lots treated for different time periods up to 7 days. Germination tests showed a progressive decrease of seed vigour depending on the duration of CDT. Proteomic analyses revealed that loss in seed vigour can be accounted for by protein changes in the dry seed and by an inability of the low vigour seeds to display a normal proteome during germination. Furthermore, the CDT strongly increased the extent of protein oxidation (i.e. carbonylation), which will in turn induce a loss of functional properties of proteins and enzymes and/or enhance their susceptibility towards proteolysis. These results highlighted essential mechanisms for germinative quality such as translational capacity and mobilization of seed storage reserves.
Arabidopsis thaliana
(L.) Heynh. seeds as a model, and carried out differential proteomics to investigate seed vigour. In our system, based on a controlled deterioration treatment (CDT), we compared seed lots treated for different time periods up to 7 days. Germination tests showed a progressive decrease of seed vigour depending on the duration of CDT. Proteomic analyses revealed that loss in seed vigour can be accounted for by protein changes in the dry seed and by an inability of the low vigour seeds to display a normal proteome during germination. Furthermore, the CDT strongly increased the extent of protein oxidation (i.e. carbonylation), which will in turn induce a loss of functional properties of proteins and enzymes and/or enhance their susceptibility towards proteolysis. These results highlighted essential mechanisms for germinative quality such as translational capacity and mobilization of seed storage reserves.
Research Interests:
Seeds are usually stored in physiological conditions in which they gradually lose their viability and vigor depending on storage conditions, storage time, and genotype. Very little is known about the underlying genetics of seed... more
Seeds are usually stored in physiological conditions in which they gradually lose their viability and vigor depending on storage conditions, storage time, and genotype. Very little is known about the underlying genetics of seed storability and seed deterioration. We analyzed a mutant in Arabidopsis disturbed in seed storability. This mutant was isolated as a grs (green-seeded) mutant in an abi3-1 (abscisic acid 3) mutant background. Genetic and physiological characterization showed that the monogenic grs mutant was not visibly green seeded and mapped on chromosome 4. This enhancer mutation did not affect the ABA sensitivity of seed germination or seed dormancy but was found to affect seed storability and seedling vigor. Seed storability was assessed in a controlled deterioration test, in which the germination capacity of the mutant decreased with the duration of the treatment. The decrease in viability and vigor was confirmed by storing the seeds in two relative humidities (RHs) for a prolonged period. At 60% RH, the mutant lost germinability, but storage at 32% RH showed no decrease of germination although seed vigor decreased. The decrease in viability and vigor could be related to an increase in conductivity, suggesting membrane deterioration. This was not affected by light conditions during imbibition, expected to influence the generation of active oxygen species. During seed maturation, ABI3 regulates several processes: acquiring dormancy and long-term storability and loss of chlorophyll. Our results indicate that GRS is a common regulator in the latter two but not of dormancy/germination.
Research Interests: Genetics, Horticulture, Biology, Seed germination, Medicine, and 15 moreSeed longevity, Seed dormancy, Biological Sciences, Plant Physiology, Chlorophyll, Plant, Polymerase Chain Reaction, Arabidopsis, Abscisic Acid, Relative Humidity, Germination, Seeds, Seedling, Dormancy, and active oxygen species
Seeds gradually lose their viability during dry storage. The damage that occurs at the biochemical level can alter the seed physiological status and is affected by the storage conditions of the seeds. Although these environmental... more
Seeds gradually lose their viability during dry storage. The damage that occurs at the biochemical level can alter the seed physiological status and is affected by the storage conditions of the seeds. Although these environmental conditions controlling loss of viability have been ...
Research Interests: Genetics, Plant Biology, Biology, Seed longevity, Seed dormancy, and 14 moreArabidopsis thaliana, Longevity, Arabidopsis, Seed Coat, Abscisic Acid, Relative Humidity, Hydrogen Peroxide, Germination, Environmental Conditions, Dormancy, Biochemistry and cell biology, Physiologia, Horticultural production, and Genetic background
Abstract Seed storage is often accompanied by a progressive loss of germination vigour and viabil-ity. In the present study, we have used Arabidopsis thaliana (L.) Heynh. seeds as a model, and carried out differential proteomics to... more
Abstract Seed storage is often accompanied by a progressive loss of germination vigour and viabil-ity. In the present study, we have used Arabidopsis thaliana (L.) Heynh. seeds as a model, and carried out differential proteomics to investigate seed vigour. In our system, based on a controlled deterioration treatment (CDT), we compared seed lots treated for different time periods up to 7 days. Germination tests showed a progressive decrease of seed vigour depending on the duration of CDT. Proteomic analyses revealed that loss in seed vigour can be accounted for by protein changes in the dry seed and by an inability of the low vigour seeds to display a normal proteome during germination. Furthermore, the CDT strongly increased the extent of protein oxidation (i.e. carbonylation), which will in turn induce a loss of functional properties of proteins and enzymes and/or enhance their susceptibility towards proteolysis. These results highlighted essential mechanisms for germinative quality such as translational capacity and mobilization of seed storage reserves.
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Research Interests: Biology, Medicine, QTL mapping, Biological Sciences, Plant Physiology, and 15 moreLongevity, Population, Reactive Oxygen Species, Plant, Polymerase Chain Reaction, Arabidopsis, Abscisic Acid, Hydrogen Peroxide, Germination, Genotype, Heat stress, Inbreeding, Quantitative Trait Loci, Mannitol, and Genetic control
Research Interests: Mass Spectrometry, Biology, Cell Cycle, Medicine, Arabidopsis thaliana, and 15 moreBiological Sciences, Plant Physiology, Mutation, Change detection, Plant, Arabidopsis, Gibberellin, Germination, Cell Wall, Medicine and Health Sciences, Embryos, Gibberellins, Metabolic control, Paclobutrazol, and Methionine Adenosyltransferase
Research Interests: Biology, Plant Proteomics, Proteomics, Seed germination, Medicine, and 15 moreGene expression, Biological Sciences, Plant Physiology, Plant, Arabidopsis, Germination, Model System, SEED, Plant species, Proteome analysis, Medicine and Health Sciences, Arabidiopsis, Proteome, PLANT PROTEINS, and Differential expression
With the growing demand for baby-leaf spinach (Spinacia oleracea L.) and an increasing ban on chemical seed treatments, problems of damping-off diseases become more apparent. Pythium ultimum has been shown to be the most common... more
With the growing demand for baby-leaf spinach (Spinacia oleracea L.) and an increasing ban on chemical seed treatments, problems of damping-off diseases become more apparent. Pythium ultimum has been shown to be the most common damping-off pathogen of spinach. Previous studies showed a large variation in pre-emergence damping-off tolerance levels among seed lots of spinach cultivars, which did not correlate with the rate of seedling emergence. In this study, we analysed if individual seed vigor-related traits, such as seed size and maturity, can influence seed tolerance towards pre-emergence infection by P. ultimum. Seeds of the same seed lots were measured for their morphological and multispectral properties on the level of a single seed. The seedling emergence from those individual seeds was assessed at different P. ultimum doses and for each individual seed, the characteristics were correlated with its emergence success. The results showed that relatively higher levels of chlorophyll fluorescence, an indicator of lesser seed maturity, had a negative association with emergence success. With increasing P. ultimum dose, the seed size and light reflectance from the pericarp, particularly with violet-blue light, showed an increasingly negative association with emergence. This indicated that smaller seeds and seeds that reflected less (violet-blue) light were more tolerant towards P. ultimum infection. A validation study with seed size and maturity fractions of a single seed lot (excluding potential genotypic and seed production effects) confirmed that seed maturity had a positive association with seedling emergence, and that seed size had a negative association with the emergence in the presence of P. ultimum. Seed size and light reflectance accounted for a small part of the variation in P. ultimum tolerance among the seed lots. Selecting the most mature seeds with relatively less light reflectance (darker pericarp) or mature seeds with smaller sizes is recommended to obtain seed lots with improved pre-emergence damping-off tolerance levels.
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Research Interests: Water, Biology, Oxidative Stress, Seed germination, Medicine, and 15 moreGene expression, Biological Sciences, Plant Physiology, Stress tolerance, Plant, Gene, Germination, Brassica oleracea, Brassica, Seeds, Time Factors, Cdna Microarray, Gene Expression Programming, Gene Expression Analysis, and Gene expression profiling
ABSTRACT
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Research Interests: Plant Biology, Flow Cytometry, Biology, Cell Cycle, Ecology, and 15 moreSeed germination, Medicine, Cell Division, Germination, Seeds, Western blot, Tubulin, Annals, Coffea arabica, Chemical Composition, PLANT PROTEINS, Time Course, Coffea, Differential expression, and reverse transcriptase polymerase chain reaction
Research Interests: Horticulture, Water, Plant Biology, Biology, Ecology, and 15 moreMedicine, Lettuce, Nitrogen, Hordeum vulgare, Plant Roots, Germination, Soybeans, Brassica, Oxygen, Seeds, Seedling, Time Factors, Humidity, Tocopherols, and Ageing
Proteomics of Arabidopsis seeds revealed the differential accumulation during germination of two housekeeping enzymes. The first corresponded to methionine synthase that catalyses the last step in the plant methionine biosynthetic... more
Proteomics of Arabidopsis seeds revealed the differential accumulation during germination of two housekeeping enzymes. The first corresponded to methionine synthase that catalyses the last step in the plant methionine biosynthetic pathway. This protein was present at low level in dry mature seeds, and its level was increased strongly at 1-day imbibition, prior to radicle emergence. Its level was not increased
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The germination of seeds of tomato [Lycopersicon esculentum (L.) Mill.] cv. Moneymaker has been compared with that of seeds of the gibberellin-deficient dwarf-mutant line ga-1, induced in the same genetic background. Germination of tomato... more
The germination of seeds of tomato [Lycopersicon esculentum (L.) Mill.] cv. Moneymaker has been compared with that of seeds of the gibberellin-deficient dwarf-mutant line ga-1, induced in the same genetic background. Germination of tomato seeds was absolutely dependent on the presence of either endogenous or exogenous gibberellins (GAs). Gibberellin A4+7 was 1000-fold more active than commercial gibberellic acid in inducing germination of the ga-1 seeds. Red light, a preincubation at 2°C, and ethylene did not stimulate germination of ga-1 seeds in the absence of GA4+7; however, fusicoccin did stimulate germination independently. Removal of the endosperm and testa layers opposite the radicle tip caused germination of ga-1 seeds in water. The seedlings and plants that develop from the detipped ga-1 seeds exhibited the extreme dwarfy phenotype that is normal to this genotype. Measurements of the mechanical resistance of the surrounding layers showed that the major action of GAs was directed to the weakening of the endosperm cells around the radicle tip. In wild-type seeds this weakening occurred in water before radicle protrusion. In ga-1 seeds a similar event was dependent on GA4+7, while fusicoccin also had some activity. Simultaneous incubation of de-embryonated endosperms and isolated axes showed that wild-type embryos contain and endosperm-weakening factor that is absent in ga-1 axes and is probably a GA. Thus, an endogenous GA facilitates germination in tomato seeds by weakening the mechanical restraint of the endosperm cells to permit radicle protrusion.
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A variety of mechanisms have been proposed to account for the extension of life span in seeds (seed longevity). In this work, we used Arabidopsis (Arabidopsis thaliana) seeds as a model and carried out differential proteomics to... more
A variety of mechanisms have been proposed to account for the extension of life span in seeds (seed longevity). In this work, we used Arabidopsis (Arabidopsis thaliana) seeds as a model and carried out differential proteomics to investigate this trait, which is of both ecological and agricultural importance. In our system based on a controlled deterioration treatment (CDT), we compared seed samples treated for different periods of time up to 7 d. Germination tests showed a progressive decrease of germination vigor depending on the duration of CDT. Proteomic analyses revealed that this loss in seed vigor can be accounted for by protein changes in the dry seeds and by an inability of the low-vigor seeds to display a normal proteome during germination. Furthermore, CDT strongly increased the extent of protein oxidation (carbonylation), which might induce a loss of functional properties of seed proteins and enzymes and/or enhance their susceptibility toward proteolysis. These results revealed essential mechanisms for seed vigor, such as translational capacity, mobilization of seed storage reserves, and detoxification efficiency. Finally, this work shows that similar molecular events accompany artificial and natural seed aging.
Research Interests: Biology, Plant Proteomics, Medicine, Arabidopsis thaliana, Biological Sciences, and 15 morePlant Physiology, Longevity, Plant, Detoxification, Glycolysis, Arabidopsis, Enzyme, Amino Acids, Germination, Life Span, PLANT PROTEINS, Protein Biosynthesis, Functional Properties, Controlled deterioration, and Natural aging
Seed deterioration during storage results in poor germination, reduced vigour, and non‐uniform seedling emergence. The aging rate depends on storage conditions and genetic factors. This study aims to identify these genetic factors... more
Seed deterioration during storage results in poor germination, reduced vigour, and non‐uniform seedling emergence. The aging rate depends on storage conditions and genetic factors. This study aims to identify these genetic factors determining the longevity of rice (Oryza sativa L.) seeds stored under experimental aging conditions mimicking long‐term dry storage. Genetic variation for tolerance to aging was studied in 300 Indica rice accessions by storing dry seeds under an elevated partial pressure of oxygen (EPPO) condition. A genome‐wide association analysis identified 11 unique genomic regions for all measured germination parameters after aging, differing from those previously identified in rice under humid experimental aging conditions. The significant single nucleotide polymorphism in the most prominent region was located within the Rc gene, encoding a basic helix‐loop‐helix transcription factor. Storage experiments using near‐isogenic rice lines (SD7‐1D (Rc) and SD7‐1d (rc) with the same allelic variation confirmed the role of the wildtype Rc gene, providing stronger tolerance to dry EPPO aging. In the seed pericarp, a functional Rc gene results in accumulation of proanthocyanidins, an important sub‐class of flavonoids having strong antioxidant activity, which may explain the variation in tolerance to dry EPPO aging.
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Research Interests: Biology, Medicine, Transcriptome, Population, Gene, and 3 moreBrassica oleracea, Brassica, and Meristem
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A seed is a marvelous adaptation for survival of the embryo for long periods of time, often under adverse environmental conditions. Such survival allows opportunities for dispersal, both in time and in space. Seed development in flowering... more
A seed is a marvelous adaptation for survival of the embryo for long periods of time, often under adverse environmental conditions. Such survival allows opportunities for dispersal, both in time and in space. Seed development in flowering plants proceeds in three discrete, although continuous, stages: early, mid-, and late embryogenesis. In early embryogenesis, there is extensive cell division activity; also, the body plan of the embryo is laid down and endosperm development begins. The maturing seeds acquire a hard, resistant seed coat and, in the dry state, have a negligible metabolism and respiration rate. Four hormones play major roles in seed development. IAA and cytokinin concentrations are high in early embryogenesis when cell divisions occur at a high frequency. IAA also plays a role in patterning and polarity establishment in the young embryo. The role of gibberellins is not as clearly defined, but they seem to be involved in expansion growth of the embryo and endosperm, thus creating a sink for photoassimilates. Abscisic acid (ABA) plays a central role in several events that occur in mid- to late embryogenesis. It is responsible for the induction of desiccation tolerance and, in some seeds, of dormancy as well. It is also responsible for the synthesis/accumulation of at least some reserve proteins. Desiccation of seed seems to act as a switch, terminating the developmental and maturation program and turning on the germinative program, which requires rehydration of the seed and, in some species, breaking of dormancy.
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Peanuts are transported by ship from production regions to all across the globe. Quality problems are frequently encountered due to increased levels of free fatty acids (FFAs) and a decline in organoleptic quality through lipid oxidation... more
Peanuts are transported by ship from production regions to all across the globe. Quality problems are frequently encountered due to increased levels of free fatty acids (FFAs) and a decline in organoleptic quality through lipid oxidation occurring during transport and storage. We studied the role of moisture (water activity, aw) in interaction with 87 days hermetic storage under air or nitrogen gas. Upon storage with air, some lipid oxidation was observed at water activity levels below 0.73. FFA levels increased at water activity levels above 0.73 and fungi proliferated at water activities above 0.80. Lipid oxidation, an increase in FFA levels and fungal growth were not observed after storage under nitrogen gas. It can be concluded that peanut storage and transport under anoxia can strongly reduce quality losses.
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Differential display analysis using dormant and non-dormant Arabidopsis thaliana (L.) Heynh seeds resulted in a set of genes that were associated with either dormancy or germination. Expression of the germination-associated genes AtRPL36B... more
Differential display analysis using dormant and non-dormant Arabidopsis thaliana (L.) Heynh seeds resulted in a set of genes that were associated with either dormancy or germination. Expression of the germination-associated genes AtRPL36B and AtRPL27B, encoding two ribosomal proteins, was undetectable in the dry seed, low in dormant seed, and high under conditions that allowed completion of germination. Expression of these
Research Interests: Plant Biology, Biology, Medicine, Seed dormancy, Signal Transduction, and 15 moreArabidopsis thaliana, Light, Temperature, Gene, Arabidopsis, Temperature Dependence, Germination, Seedling, Cape Verde Islands, Low Temperature, Dormancy, Differential Display, Gibberellic Acid, Planta, and Ribosomal Protein
Spinach growers face increasing problems of damping-off in the production of fresh-market (baby-leaf) spinach due to increasing restrictions on chemical treatments. Damping-off-tolerant cultivars are increasingly important, requiring... more
Spinach growers face increasing problems of damping-off in the production of fresh-market (baby-leaf) spinach due to increasing restrictions on chemical treatments. Damping-off-tolerant cultivars are increasingly important, requiring proper evaluation methods. From three locations in The Netherlands with a history of spinach cultivation and from one location in France, potential damping-off pathogens were isolated from the soil, identified to species or genus, and tested for their pathogenicity. Pythium ultimum was the most prevalent pathogen in those fields, causing spinach pre- and postemergence damping-off. Eight spinach cultivars with two or three seed lots each were evaluated at the same field locations and in a greenhouse with soil sampled from one of the Dutch field sites. Preemergence damping-off was more discriminating for differences among the cultivars than postemergence damping-off. Variation in levels of infection among trials, replicates, and seed lots of the same cult...
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Research Interests:
Research Interests:
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The production of high-quality seed is the basis for a durable a profitable agriculture. After production, seed is processed, conditioned, stored, shipped and germinated. For quality assurance, seed quality has to be controlled at all... more
The production of high-quality seed is the basis for a durable a profitable agriculture. After production, seed is processed, conditioned, stored, shipped and germinated. For quality assurance, seed quality has to be controlled at all steps of the production chain. Seed functioning is accompanied by programmed transitions from cell proliferation to quiescence upon maturation and from quiescence to reinitiation of cellular metabolism upon imbibition. Despite the obvious importance of these control mechanisms, very little information is available at the molecular level concerning those elements that regulate seed germination. In the present study, the induction of cell cycle activity and the regulation of ß-tubulin expression is related to the water content and other physical properties of the seed.
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Research Interests:
Several ecotypes (Landsberg erecta, Enkheim, Cape Verde islands and C24) and mutants (abal-1, abi3-7, gal-1 and tt4-1) of Arabidopsis thaliana L. were subjected to a variety of seed quality tests to assess genetic variation. The wild type... more
Several ecotypes (Landsberg erecta, Enkheim, Cape Verde islands and C24) and mutants (abal-1, abi3-7, gal-1 and tt4-1) of Arabidopsis thaliana L. were subjected to a variety of seed quality tests to assess genetic variation. The wild type (Landsberg erecta) and two mutants (abi3-7, tt4-1) gave close to 100% germination at 25°C whilst other genotypes and mutants showed varying degrees of dormancy. A controlled deterioration assay was developed to compare genotypes with regard to their storability. Equilibration of the seeds at 85% relative humidity and subsequent hermetic storage at 40°C was more discriminatory in identifying differences in storability than was equilibration at 75% relative humidity followed by storage at 40 or 50°C. With longer deterioration treatments, germination was reduced and average germination time and frequency of abnormal seedlings increased. This test revealed clear differences in seed stress tolerance amongst genotypes. Additional differences in seed quality were observed in germination tests performed at sub-optimal conditions, such as low temperatures (10 and 15°C) or under osmotic stress (-0.25 MPa and -0.50 MPa). The observed differences in seed quality and the assays developed can be used to identify genes involved in different aspects of seed quality.
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Seed germination and seedling establishment are the main factors for a successful start of a crop, determining crop health, weed suppression and overall crop performance. They are critical, but sensitive phases in crop production. High... more
Seed germination and seedling establishment are the main factors for a successful start of a crop, determining crop health, weed suppression and overall crop performance. They are critical, but sensitive phases in crop production. High seed vigour and appropriate seed microbiota significantly contribute to the resilience of seedlings. This opinion paper is based on a review of relevant literature, two case studies with wheat and carrot and a subsequent stakeholder consultation in the framework of the European project LIVESEED. It presents a seed health strategy for organic farming systems that accounts for dynamic processes behind seed and plant health, taking advantage of the contributions of seed vigour and seed microbiota. Seed and plant health are understood as a continuum. Benefits of seed vigour and microbiota are showcased. Recommendations are given for organic seed production, seed processing and storage, as well as organic plant breeding and future research. In conclusion, ...
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Research Interests:
Through evolution, plants produce seeds with variation in speed of germination and, for instance, dormancy to spread the risk of germinating in the wrong season. Although domestication and breeding has created crops with more rapid... more
Through evolution, plants produce seeds with variation in speed of germination and, for instance, dormancy to spread the risk of germinating in the wrong season. Although domestication and breeding has created crops with more rapid germinating seeds, compared with their wild relatives, for many crops the variation in performance is such that upgrading and seed treatments are needed to create starting materials for commercial crop production. Measures are needed during the production itself, and during harvesting, cleaning and drying. In this chapter we will report on various factors that influence organic seed quality and availability, on methods for seed sorting, upgrading and storage, on methods of seed sanitation that are applicable for organic seeds and on seed certification systems. We will point on research that has been performed in the past and resulted in commercially available methods for upgrading of seed quality and on promising new research lines.
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Seed storage is often accompanied by a progressive loss of germination vigour and viabil-ity. In the present study, we have used Arabidopsis thaliana (L.) Heynh. seeds as a model, and carried out differential proteomics to investigate... more
Seed storage is often accompanied by a progressive loss of germination vigour and viabil-ity. In the present study, we have used Arabidopsis thaliana (L.) Heynh. seeds as a model, and carried out differential proteomics to investigate seed vigour. In our system, based on a controlled deterioration treatment (CDT), we compared seed lots treated for different time periods up to 7 days. Germination tests showed a progressive decrease of seed vigour depending on the duration of CDT. Proteomic analyses revealed that loss in seed vigour can be accounted for by protein changes in the dry seed and by an inability of the low vigour seeds to display a normal proteome during germination. Furthermore, the CDT strongly increased the extent of protein oxidation (i.e. carbonylation), which will in turn induce a loss of functional properties of proteins and enzymes and/or enhance their susceptibility towards proteolysis. These results highlighted essential mechanisms for germinative quality such as...
Research Interests: Biology and Germination
A mutable allele of the An1 locus in Petunia hybrida has given rise to a multiple series of stable derivative alleles. Anthocyanin concentration in mature flowers of these mutants (an1 +/p/an1) decreases from the wild-type red to the... more
A mutable allele of the An1 locus in Petunia hybrida has given rise to a multiple series of stable derivative alleles. Anthocyanin concentration in mature flowers of these mutants (an1 +/p/an1) decreases from the wild-type red to the recessive white in a continuous series. Anthocyanin composition changes regularly: the ratio of peonidin to cyanidin is 3.5 for an an1 +/+/an1 and 1.2 for an an1 +/p5/an1 mutant. Analysis of anthocyanins during flower development indicates that these differences in composition are due to the specific state of the An1 locus and not to anthocyanin concentration. Anthocyanin concentration in flowers of the allelic series for An1 correlates with the activity of the enzymes UDP-glucose: flavonoid-3-O-glucosyltransferase and SAM: anthocyanin-3′-O-methyltransferase. The same correlations were found for members of a comparable allelic series at the An2 locus. The possibility that the correlation between the enzyme activities is due to the occurrence of a mul...
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We examined the role of gibberellins (GAs) in germination of Arabidopsis seeds by a proteomic approach. For that purpose, we used two systems. The first system consisted of seeds of the GA-deficient ga1 mutant, and the second corresponded... more
We examined the role of gibberellins (GAs) in germination of Arabidopsis seeds by a proteomic approach. For that purpose, we used two systems. The first system consisted of seeds of the GA-deficient ga1 mutant, and the second corresponded to wild-type seeds incubated in paclobutrazol, a specific GA biosynthesis inhibitor. With both systems, radicle protrusion was strictly dependent on exogenous GAs. The proteomic analysis indicated that GAs do not participate in many processes involved in germination sensu stricto (prior to radicle protrusion), as, for example, the initial mobilization of seed protein and lipid reserves. Out of 46 protein changes detected during germination sensu stricto (1 d of incubation on water), only one, corresponding to the cytoskeleton component -2,4 tubulin, appeared to depend on the action of GAs. An increase in this protein spot was noted for the wild-type seeds but not for the ga1 seeds incubated for 1 d on water. In contrast, GAs appeared to be involved, directly or indirectly, in controlling the abundance of several proteins associated with radicle protrusion. This is the case for two isoforms of S-adenosyl-methionine (Ado-Met) synthetase, which catalyzes the formation of Ado-Met from Met and ATP. Owing to the housekeeping functions of Ado-Met, this event is presumably required for germination and seedling establishment, and might represent a major metabolic control of seedling establishment. GAs can also play a role in controlling the abundance of a -glucosidase, which might be involved in the embryo cell wall loosening needed for cell elongation and radicle extension.
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A variety of mechanisms have been proposed to account for the extension of life span in seeds (seed longevity). In this work, we used Arabidopsis (Arabidopsis thaliana) seeds as a model and carried out differential proteomics to... more
A variety of mechanisms have been proposed to account for the extension of life span in seeds (seed longevity). In this work, we used Arabidopsis (Arabidopsis thaliana) seeds as a model and carried out differential proteomics to investigate this trait, which is of both ecological and agricultural importance. In our system based on a controlled deterioration treatment (CDT), we compared seed samples treated for different periods of time up to 7 d. Germination tests showed a progressive decrease of germination vigor depending on the duration of CDT. Proteomic analyses revealed that this loss in seed vigor can be accounted for by protein changes in the dry seeds and by an inability of the low-vigor seeds to display a normal proteome during germination. Furthermore, CDT strongly increased the extent of protein oxidation (carbonylation), which might induce a loss of functional properties of seed proteins and enzymes and/or enhance their susceptibility toward proteolysis. These results revealed essential mechanisms for seed vigor, such as translational capacity, mobilization of seed storage reserves, and detoxification efficiency. Finally, this work shows that similar molecular events accompany artificial and natural seed aging.