Research Institute of Biology and Agriculture, University of Science and Technology Beijing, Beijing 100083, China; Beijing Engineering Laboratory of Main Crop Bio-Tech Breeding, Zhongzhi International Institute of Agricultural Biosciences, Beijing 100192, China.
Research Institute of Biology and Agriculture, University of Science and Technology Beijing, Beijing 100083, China.
Mol Plant. 2023 Aug 7;16(8):1321-1338. doi: 10.1016/j.molp.2023.07.010. Epub 2023 Jul 26.
Because of its significance for plant male fertility and, hence, direct impact on crop yield, pollen exine development has inspired decades of scientific inquiry. However, the molecular mechanism underlying exine formation and thickness remains elusive. In this study, we identified that a previously unrecognized repressor, ZmMS1/ZmLBD30, controls proper pollen exine development in maize. Using an ms1 mutant with aberrantly thickened exine, we cloned a male-sterility gene, ZmMs1, which encodes a tapetum-specific lateral organ boundary domain transcription factor, ZmLBD30. We showed that ZmMs1/ZmLBD30 is initially turned on by a transcriptional activation cascade of ZmbHLH51-ZmMYB84-ZmMS7, and then it serves as a repressor to shut down this cascade via feedback repression to ensure timely tapetal degeneration and proper level of exine. This activation-feedback repression loop regulating male fertility is conserved in maize and sorghum, and similar regulatory mechanism may also exist in other flowering plants such as rice and Arabidopsis. Collectively, these findings reveal a novel regulatory mechanism of pollen exine development by which a long-sought master repressor of upstream activators prevents excessive exine formation.
由于花粉外壁的发育对植物雄性育性具有重要意义，直接影响作物产量，因此几十年来一直激发着科学界的研究兴趣。然而，外壁形成和厚度的分子机制仍然难以捉摸。在这项研究中，我们鉴定出一个以前未被识别的抑制剂 ZmMS1/ZmLBD30 控制着玉米花粉外壁的正常发育。利用外壁异常增厚的 ms1 突变体，我们克隆了一个雄性不育基因 ZmMs1，它编码一个特异于绒毡层的侧向器官边界结构域转录因子 ZmLBD30。我们表明，ZmMs1/ZmLBD30 最初由一个转录激活级联反应 ZmbHLH51-ZmMYB84-ZmMS7 启动，然后作为一个抑制剂通过反馈抑制来关闭这个级联反应，以确保绒毡层的适时退化和适当的外壁水平。这种调节花粉外壁发育的激活-反馈抑制环在玉米和高粱中是保守的，类似的调控机制可能也存在于水稻和拟南芥等其他开花植物中。总之，这些发现揭示了花粉外壁发育的一种新的调控机制，其中一个长期寻求的上游激活物的主抑制剂防止了外壁的过度形成。
