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THERMO-INHIBITION OF SEED GERMINATION AND PRE-GERMINATION SEED VERNALIZATION IN WINTER ANNUAL WEEDS

冬季一年生杂草种子萌发的热抑制和萌发前种子春化

基本信息

批准号：
16580009
负责人：
YOSHIOKA Toshihito
金额：
$ 2.37万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

1.Thermo-inhibition of seed germinationWhen the seeds sense that the temperature is too high to germinate, they enhance ABA biosynthesis and maintain high ABA contents to prevent their germination. If the temperature is much higher, the seeds increase their sensitivities to ABA, maintaining the enhanced ABA biosynthesis, but not affecting the bioactive GA_1 contents. Therefore, for reducing the endogenous ABA contents sufficiently to rescue seed germination from the severe thermoinhibition, the inhibition of ABA synthesis must be combined with the enhancement of ABA catabolism by exogenous GA. This temperature-sensory mechanism mediated by ABA will play a decisive role in the control of life cycles in winter annual weeds.2.Pre-germination seed vernalizationSeeds of facultative winter annuals germinate both in autumn and spring. When soil-buried seeds of a winter annual, Conyza canadensis, had been exposed to low temperatures in winter, plants from spring-germinating seeds showed early flowering traits. This phenomenon was defined as pre-germination seed vernalization (PGSV). Out of 103 winter annuals, 21 species expressed the characteristic of pre-germination seed vernalization, showing no induction of secondary seed dormancy by the chilling. We conclude that pre-germination seed vernalization is a key ecological factor regulating life cycle of facultative winter annuals, resulting in early flowering of the spring-germinated plants. Using subtractive screenings, thirty genes were isolated from the chilled seeds of C.canadensis.

1.种子发芽的热抑制当种子感知到温度过高而无法发芽时，就会增强ABA的生物合成，维持较高的ABA含量，从而阻止其发芽。如果温度较高，种子对ABA的敏感性增加，维持ABA生物合成的增强，但不影响生物活性GA_1含量。因此，为了充分降低内源ABA含量以挽救种子萌发免受严重的热抑制，必须将ABA合成的抑制与外源GA对ABA分解代谢的增强相结合。 ABA介导的这种温度感觉机制将对冬季一年生杂草生命周期的控制起到决定性作用。2.发芽前种子春化兼性冬季一年生杂草种子在秋季和春季均萌发。当冬季一年生植物 Conyza canadensis 埋藏在土壤中的种子暴露在冬季低温下时，春季发芽的种子的植物表现出早期开花的特征。这种现象被定义为发芽前种子春化（PGSV）。在 103 种冬季一年生植物中，有 21 种表现出发芽前种子春化的特征，没有表现出受低温诱导的二次种子休眠。我们得出的结论是，发芽前种子春化是调节兼性冬季一年生植物生命周期的关键生态因素，导致春季发芽植物提前开花。通过消减筛选，从 C.canadensis 的冷冻种子中分离出 30 个基因。