The role of the testa during development and in establishment of dormancy of the legume seed

Smýkal, Petr; Vernoud, Vanessa; Blair, Matthew W.; Soukup, Aleš; Thompson, Richard

doi:10.3389/fpls.2014.00351

Cited by 208 publications

(311 citation statements)

References 212 publications

(332 reference statements)

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“…Hard seeds fail to imbibe water within the prescribed test period (Wang and Hampton, 1989). Hard seed in legumes occurs quite promiscuously in every seed lot but varies in both degree and number from one species to another (Smýkal et al, 2014). High hard seed content in perennial legumes Centrosema pubescens can lead to delayed or decreased seedling emergence.…”

Section: Resultsmentioning

confidence: 99%

Comparative study of seed yield and seed quality of advanced lines and commercial varieties of red clover (Trifolium pratense L.)

Petkovic

Pržulj

Radic

et al. 2017

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Red clover (Trifolium pratense L.) is one of the most important forage legumes in areas with acidic and nutrient poorer soils where alfalfa fails to growth. In 2010-2011 years period we studied four advanced lines and four commercial varieties of red clover, which are widely used in the production in Bosnia and Herzegovina. Our results showed that the variation in grain yield, thousand kernel weight and germination energy was under control of growth. Across genotypes seed yield in 2010 and 2011 was 205 and 223 kg ha -1 , respectively. The highest yield of seed was obtained from second growth in the second year. Extreme precipitation during anthesis and grain filling and ripening in 2010 negatively affected red clover seed production. Advanced line DS-2 had the highest grain yield (234 kg ha -1 ) and thousand kernel weight (1.75 g). Low seeds yields of the tested genotypes are questioning the cost-effectiveness of red clover seed production at this site.

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Section: Resultsmentioning

confidence: 99%

Comparative study of seed yield and seed quality of advanced lines and commercial varieties of red clover (Trifolium pratense L.)

Petkovic

Pržulj

Radic

et al. 2017

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“…Physical dormancy plays a key role in protecting seeds against microbial attacks and predators and maintaining seed banks in soils (3)(4)(5). This type of dormancy has been found in at least 17 plant families and is very common in legume species (2,6,7). Seed exhibiting physical dormancy is characterized by specific morphological features, including a water-impermeable palisade cell layer covered by intact cuticles in the hard seed coat.…”

mentioning

confidence: 99%

A class II KNOX gene, KNOX4 , controls seed physical dormancy

Chai

Zhou

Molina

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Physical dormancy of seed is an adaptive trait that widely exists in higher plants. This kind of dormancy is caused by a waterimpermeable layer that blocks water and oxygen from the surrounding environment and keeps embryos in a viable status for a long time. Most of the work on hardseededness has focused on morphological structure and phenolic content of seed coat. The molecular mechanism underlying physical dormancy remains largely elusive. By screening a large number of Tnt1 retrotransposontagged Medicago truncatula lines, we identified nondormant seed mutants from this model legume species. Unlike wild-type hard seeds exhibiting physical dormancy, the mature mutant seeds imbibed water quickly and germinated easily, without the need for scarification. Microscopic observations of cross sections showed that the mutant phenotype was caused by a dysfunctional palisade cuticle layer in the seed coat. Chemical analysis found differences in lipid monomer composition between the wild-type and mutant seed coats. Genetic and molecular analyses revealed that a class II KNOTTED-like homeobox (KNOXII) gene, KNOX4, was responsible for the loss of physical dormancy in the seeds of the mutants. Microarray and chromatin immunoprecipitation analyses identified CYP86A, a gene associated with cutin biosynthesis, as one of the downstream target genes of KNOX4. This study elucidated a novel molecular mechanism of physical dormancy and revealed a new role of class II KNOX genes. Furthermore, KNOX4-like genes exist widely in seed plants but are lacking in nonseed species, indicating that KNOX4 may have diverged from the other KNOXII genes during the evolution of seed plants.S eed dormancy is a complex adaptive trait of higher plants that allows embryos to survive extended periods of unfavorable environmental conditions (1). Over the course of evolution, plant seeds have evolved diverse dormancy forms in response to various climates to maintain viability (2). Physical dormancy, also termed hardseededness, is an exogenous dormancy caused by a water-impermeable hard seed coat. Physical dormancy plays a key role in protecting seeds against microbial attacks and predators and maintaining seed banks in soils (3-5). This type of dormancy has been found in at least 17 plant families and is very common in legume species (2, 6, 7). Seed exhibiting physical dormancy is characterized by specific morphological features, including a water-impermeable palisade cell layer covered by intact cuticles in the hard seed coat. This structure blocks water and oxygen from its surrounding environment and preserves seeds in a viable status for a long time, sometimes for more than hundreds of years (8). Another common type of seed dormancy is physiological dormancy, which is caused by endogenous factors (e.g., abscisic acid) in embryos. Most molecular studies on seed dormancy have focused on physiological dormancy, using model species Arabidopsis thaliana (9, 10).However, A. thaliana seed is water-permeable, and thus not a suitable model to study physical dor...

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“…Having a high proportion of nondormant seeds facilitates good crop establishment, and, in the case of soft-seeded legumes, reduces cooking time. Reducing seed coat thickness led to a concurrent reduction of seed coat impermeability during legume domestication [79]. Conversely, low seed dormancy levels can reduce seed viability and trigger preharvest sprouting, causing yield losses in cereals [80].…”

Section: Domestication Has Left Signatures Both On Morphological As Wmentioning

confidence: 99%

The Impact of Genetic Changes during Crop Domestication

et al. 2018

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Abstract:Humans have domesticated hundreds of plant and animal species as sources of food, fiber, forage, and tools over the past 12,000 years, with manifold effects on both human society and the genetic structure of the domesticated species. The outcomes of crop domestication were shaped by selection driven by human preferences, cultivation practices, and agricultural environments, as well as other population genetic processes flowing from the ensuing reduction in effective population size. It is obvious that any selection imposes a reduction of diversity, favoring preferred genotypes, such as nonshattering seeds or increased palatability. Furthermore, agricultural practices greatly reduced effective population sizes of crops, allowing genetic drift to alter genotype frequencies. Current advances in molecular technologies, particularly of genome sequencing, provide evidence of human selection acting on numerous loci during and after crop domestication. Population-level molecular analyses also enable us to clarify the demographic histories of the domestication process itself, which, together with expanded archaeological studies, can illuminate the origins of crops. Domesticated plant species are found in 160 taxonomic families. Approximately 2500 species have undergone some degree of domestication, and 250 species are considered to be fully domesticated. The evolutionary trajectory from wild to crop species is a complex process. Archaeological records suggest that there was a period of predomestication cultivation while humans first began the deliberate planting of wild stands that had favorable traits. Later, crops likely diversified as they were grown in new areas, sometimes beyond the climatic niche of their wild relatives. However, the speed and level of human intentionality during domestication remains a topic of active discussion. These processes led to the so-called domestication syndrome, that is, a group of traits that can arise through human preferences for ease of harvest and growth advantages under human propagation. These traits included reduced dispersal ability of seeds and fruits, changes to plant structure, and changes to plant defensive characteristics and palatability. Domestication implies the action of selective sweeps on standing genetic variation, as well as new genetic variation introduced via mutation or introgression. Furthermore, genetic bottlenecks during domestication or during founding events as crops moved away from their centers of origin may have further altered gene pools. To date, a few hundred genes and loci have been identified by classical genetic and association mapping as targets of domestication and postdomestication divergence. However, only a few of these have been characterized, and for even fewer is the role of the wild-type allele in natural populations understood. After domestication, only favorable haplotypes are retained around selected genes, which creates a genetic valley with extremely low genetic diversity. These "selective sweeps" can allow mildly deleterious...

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The role of the testa during development and in establishment of dormancy of the legume seed

Cited by 208 publications

References 212 publications

Comparative study of seed yield and seed quality of advanced lines and commercial varieties of red clover (Trifolium pratense L.)

Comparative study of seed yield and seed quality of advanced lines and commercial varieties of red clover (Trifolium pratense L.)

A class II KNOX gene, KNOX4 , controls seed physical dormancy

The Impact of Genetic Changes during Crop Domestication

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