种子的脱水行为及其分子机制

Desiccation Behavior of Seeds and Their Molecular Mechanisms

成熟脱水是种子发育的末端事件。根据种子的脱水行为 ,可以把种子分为正常性、顽拗性和中间性种子。许多过程或者机制授予或者提高种子的脱水耐性 ,不同的过程可能在不同的水合水平上对水分丧失起保护作用 ,这些过程的缺乏或者无效表达可能决定个别物种的种子的脱水敏感性程度。到目前为止 ,涉及种子脱水耐性的过程或者机制有 :细胞内脱分化 ;代谢的‘关闭’ ;抗氧化系统的存在和有效运转 ;保护性分子 (包括胚胎发育后期高丰度表达蛋白 ,蔗糖、寡糖或者半乳糖苷环多醇 ,亲水脂分子 ,油素 )的存在 ;以及在重新水合过程中修复机制的存在和运转。

Maturation drying is a terminal event of seed development.Seeds can be categorized into orthodox,recalcitrant and intermediate seeds depending on their storage behaviour.A number of processes or mechanisms have been suggested to confer,or contribute to,desiccation tolerance of seeds. Different processes may confer protection against the consequences of loss of water at different hydration levels, and the absence or ineffective expression of one or more of these could determine the relative degree of desiccation sensitivity of seeds of individual species.The processes or mechanisms that have been implicated in desiccation tolerance of seeds to date are: intracellular de-differentiation;metabolic ‘switching off’; presence and efficient operation of antioxidant systems; accumulation of putatively protective molecules including late embryogenic abundant proteins, sucrose and certain oligosaccharides or galactosyl,amphipathic molecules, as well as oleosins; and the presence and operation of repair systems during rehydration of seeds.