Lopez-Molina L, Mongrand S, Chua N H
Laboratory of Plant Molecular Biology, The Rockefeller University, New York, NY 10021-6399, USA.
Proc Natl Acad Sci U S A. 2001 Apr 10;98(8):4782-7. doi: 10.1073/pnas.081594298. Epub 2001 Apr 3.
Seed dormancy is a trait of considerable adaptive significance because it maximizes seedling survival by preventing premature germination under unfavorable conditions. Understanding how seeds break dormancy and initiate growth is also of great agricultural and biotechnological interest. Abscisic acid (ABA) plays primary regulatory roles in the initiation and maintenance of seed dormancy. Here we report that the basic leucine zipper transcription factor ABI5 confers an enhanced response to exogenous ABA during germination, and seedling establishment, as well as subsequent vegetative growth. These responses correlate with total ABI5 levels. We show that ABI5 expression defines a narrow developmental window following germination, during which plants monitor the environmental osmotic status before initiating vegetative growth. ABI5 is necessary to maintain germinated embryos in a quiescent state thereby protecting plants from drought. As expected for a key player in ABA-triggered processes, ABI5 protein accumulation, phosphorylation, stability, and activity are highly regulated by ABA during germination and early seedling growth.
种子休眠是一种具有重要适应意义的特性，因为它通过防止种子在不利条件下过早萌发，从而使幼苗存活率最大化。了解种子如何打破休眠并开始生长，在农业和生物技术领域也备受关注。脱落酸（ABA）在种子休眠的起始和维持过程中发挥着主要调控作用。在此，我们报告碱性亮氨酸拉链转录因子ABI5在种子萌发、幼苗建立以及随后的营养生长过程中，赋予了对外源ABA增强的响应。这些响应与ABI5的总水平相关。我们表明，ABI5的表达界定了萌发后一个狭窄的发育窗口，在此期间，植物在开始营养生长之前监测环境渗透状态。ABI5对于将已萌发的胚维持在静止状态是必要的，从而保护植物免受干旱影响。正如在ABA触发过程中的关键参与者所预期的那样，在萌发和幼苗早期生长期间，ABA对ABI5蛋白的积累、磷酸化、稳定性和活性进行了高度调控。
