成熟脱水对种子发育和萌发的作用

成熟脱水是正常性种子发育的末端事件。种子在成熟时胚的脱水耐性增加；当种子萌发时胚变得不耐脱水。当种子获得脱水耐性时，糖、蛋白质和抗氧化防御系统等保护性物质积累；当脱水耐性丧失时，这些物质被降解。成熟脱水是种子从发育过程向萌发过程转变的“开关”，它降低发育的蛋白质和ｍＲＮＡ的合成，终止发育事件和促进萌发事件。顽拗性种子不经历成熟脱水的发育阶段，对脱水高度敏感。

ROLE OF MATURATION DRYING IN SEED DEVELOPMENT AND GERMINATION

Maturation drying is a terminal event in the development of orthodox seeds. The desiccation tolerance of embryos becomes more tolerant as seeds mature and less tolerant as seeds germinate. The protective substances, such as sugars,proteins and antioxidant defence systems,are observed to accumulate in orthodox seeds when tolerance is acquired and to degrade when tolerance is lost. Maturation drying could be a "switch" in the transition from seed development to germination,and decline the syntheses of developmental proteins and developmental mRNAs. And the developmental events are terminated and germinant events are stimulated by maturation drying. Recalcitrant seeds,which do not undergo the developmental stage of maturation drying,are highly sensitive to desiccation throughout seed development.