National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology and Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
Proc Natl Acad Sci U S A. 2013 Sep 17;110(38):15485-90. doi: 10.1073/pnas.1304651110. Epub 2013 Aug 28.
The transition from dormancy to germination in seeds is a key physiological process during the lifecycle of plants. Abscisic acid (ABA) is the sole plant hormone known to maintain seed dormancy; it acts through a gene expression network involving the transcription factor ABSCISIC ACID INSENSITIVE 3 (ABI3). However, whether other phytohormone pathways function in the maintenance of seed dormancy in response to environmental and internal signals remains an important question. Here, we show that the plant growth hormone auxin, which acts as a versatile trigger in many developmental processes, also plays a critical role in seed dormancy in Arabidopsis. We show that disruptions in auxin signaling in MIR160-overexpressing plants, auxin receptor mutants, or auxin biosynthesis mutants dramatically release seed dormancy, whereas increases in auxin signaling or biosynthesis greatly enhance seed dormancy. Auxin action in seed dormancy requires the ABA signaling pathway (and vice versa), indicating that the roles of auxin and ABA in seed dormancy are interdependent. Furthermore, we show that auxin acts upstream of the major regulator of seed dormancy, ABI3, by recruiting the auxin response factors AUXIN RESPONSE FACTOR 10 and AUXIN RESPONSE FACTOR 16 to control the expression of ABI3 during seed germination. Our study, thus, uncovers a previously unrecognized regulatory factor of seed dormancy and a coordinating network of auxin and ABA signaling in this important process.
种子从休眠到萌发的转变是植物生命周期中的一个关键生理过程。脱落酸（ABA）是唯一已知能维持种子休眠的植物激素；它通过一个涉及转录因子 ABA 不敏感 3（ABI3）的基因表达网络发挥作用。然而，其他植物激素途径是否在响应环境和内部信号维持种子休眠中起作用，仍是一个重要问题。在这里，我们表明植物生长激素生长素，作为许多发育过程中的多功能触发因素，在拟南芥种子休眠中也起着关键作用。我们表明，在 MIR160 过表达植物、生长素受体突变体或生长素生物合成突变体中生长素信号的中断会显著释放种子休眠，而生长素信号的增加或生物合成的增加则会极大地增强种子休眠。生长素在种子休眠中的作用需要 ABA 信号通路（反之亦然），表明生长素和 ABA 在种子休眠中的作用是相互依存的。此外，我们表明生长素通过招募生长素反应因子 AUXIN RESPONSE FACTOR 10 和 AUXIN RESPONSE FACTOR 16 来作用于种子休眠的主要调节因子 ABI3，从而在上游控制 ABI3 在种子萌发过程中的表达。因此，我们的研究揭示了种子休眠的一个以前未被识别的调节因子，以及生长素和 ABA 信号在这一重要过程中的协调网络。
