Description
Legume forage seeds have evolved a specific dormancy trait, physical dormancy, to inhibit germination until favorable conditions appear. Physical dormancy is an adaptive trait that widely exists in higher plants and plays a vital role in maintaining natural seed banks. This kind of dormancy is caused by a waterimpermeable layer that blocks water and oxygen from the surrounding environment. The outermost cuticle of the seed coat is critical for establishing seed physical dormancy. The molecular mechanism underlying physical dormancy remains largely elusive. Using Medicago (Medicago truncatula) as a model, we set up the legume plant to study seed physical dormancy. Our studies suggest that a class II KNOTTED-like homeobox (KNOXII) gene, KNOX4 is a transcription factor critical for controlling hardseededness. We reported the function of a seed coat β-ketoacyl-CoA synthase, KCS12. kcs12 mutant seeds lost physical dormancy and were able to absorb water without scarification treatment. Chemical analysis revealed that concentrations of C24:0 lipid polyester monomers are significantly decreased in knox4 and kcs12mutant seeds, indicating that both genes are critical to cuticle formation in the seed coat. These findings define a molecular mechanism by which KNOX4 and KCS12 control formation of the seed coat and seed physical dormancy. More mutant identification are performed to understand more about the mechanism of physical dormancy and legume forage improvement, like in alfalfa.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
The Molecular Mechanism of Seed Physical Dormancy in Legume Forage
Legume forage seeds have evolved a specific dormancy trait, physical dormancy, to inhibit germination until favorable conditions appear. Physical dormancy is an adaptive trait that widely exists in higher plants and plays a vital role in maintaining natural seed banks. This kind of dormancy is caused by a waterimpermeable layer that blocks water and oxygen from the surrounding environment. The outermost cuticle of the seed coat is critical for establishing seed physical dormancy. The molecular mechanism underlying physical dormancy remains largely elusive. Using Medicago (Medicago truncatula) as a model, we set up the legume plant to study seed physical dormancy. Our studies suggest that a class II KNOTTED-like homeobox (KNOXII) gene, KNOX4 is a transcription factor critical for controlling hardseededness. We reported the function of a seed coat β-ketoacyl-CoA synthase, KCS12. kcs12 mutant seeds lost physical dormancy and were able to absorb water without scarification treatment. Chemical analysis revealed that concentrations of C24:0 lipid polyester monomers are significantly decreased in knox4 and kcs12mutant seeds, indicating that both genes are critical to cuticle formation in the seed coat. These findings define a molecular mechanism by which KNOX4 and KCS12 control formation of the seed coat and seed physical dormancy. More mutant identification are performed to understand more about the mechanism of physical dormancy and legume forage improvement, like in alfalfa.
