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THE MECHANISM OF LIFE CYCLE REGULATION IN WINTER ANNUAL PLANTS VIA TEMPERATURE RESPONSEVENSS OF SEEDS

冬季一年生植物种子温度响应调控生命周期的机制

基本信息

批准号：
12640607
负责人：
YOSHIOKA Toshihito
金额：
$ 2.56万
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：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12640607/
关键词：
LIFE CYCLE EVOLUTION WINTER ANNUAL PLANT SEED GERMINATION FLOWERING TIMING VERNALIZATION ABSCISIC ACID GIBBRELLIN ECO-PHYSIOLOGY 植物生活環制御 NCED遺伝子生活環制御種子発芽

项目摘要

Winter annual plants have adapted their life cycles to seasonally changing temperature. To know how they have evolved the life cycles we investigated the eco-physiological mechanisms controlling the germination timing, and proposed a model as follows.Winter annuals escape their growth in summer as soil-buried seeds. Germination of the seeds is inhibited during summer because the maximum temperatures for germination were just below the minimum temperatures in the soil. The seeds germinate in autumn when the temperature range for germination and those in the soil overlap. That is, the buried seeds detect appropriate germination timing by sensing the high temperatures.When seeds sense the temperature is too high to germinate, they enhance ABA biosynthesis and maintain a high ABA level to prevent their germination. Endogenous GA level is low, but it will play a positive role on ABA degradation. This situation, thermo-inhibition at the lower supraoptimal temperature, is overcome by inhibition of ABA synthesis. If the temperature is much higher, the seeds raise their sensitivities to ABA in addition to the enhanced ABA synthesis, but not affect the GA level. Therefore, for restoring the seed germination at the supraoptimal temperature, a combined action of the inhibition of ABA synthesis and the enhancement of ABA degradation is necessary.

冬季一年生植物已经适应了它们的生命周期以适应季节性变化的温度。为了了解它们的生活史是如何演变的，我们研究了控制萌发时间的生理生态机制，并提出了一个模型：冬季一年生植物在夏季以土埋种子的形式逃避生长。种子的发芽在夏季受到抑制，因为发芽的最高温度刚好低于土壤中的最低温度。种子在秋季发芽，此时发芽温度范围与土壤中的温度范围重叠。也就是说，埋藏的种子通过感知高温来确定合适的发芽时间，当种子感觉到温度过高而不能发芽时，它们会增强阿坝的生物合成，并保持高水平的阿坝来阻止种子发芽。内源GA水平较低，但对阿坝的降解起积极作用。这种情况，在较低的超最适温度下的热抑制，通过抑制阿坝合成来克服。当温度过高时，种子对阿坝的敏感性增加，阿坝合成增加，但GA含量不受影响。因此，在超适温条件下恢复种子萌发，抑制阿坝合成和促进阿坝降解的联合作用是必要的。