Feedback regulation of m6A modification creates local auxin maxima essential for rice microsporogenesis. Oryza sativa

N6-methyladenosine (m6A) RNA modification and its effectors modulate various plant developmental processes, yet whether and how these effectors are transcriptionally regulated to confer functional specificity so far remain elusive. Herein, we show that a rice C2H2 zinc finger protein, OsZAF, specifically activates the expression of OsFIP37 encoding a core component of the m6A methyltransferase complex during microsporogenesis in rice anthers. OsFIP37 in turn facilitates m6A modification and stabilization of an auxin biosynthesis gene OsYUCCA3 to promote auxin biosynthesis in anthers. This elevates auxin levels coinciding with upregulation of an auxin response factor OsARF12 that positively regulates OsZAF, thus creating a positive feedback circuit whereby OsFIP37 is continuously activated for local auxin production. Our findings reveal that OsZAF-dependent feedback regulation of m6A modification is integral to local auxin biosynthesis and signaling in anthers, which facilitates timely generation of auxin maxima required for male meiosis in rice.

N6-甲基腺嘌呤（N6-methyladenosine，m6A）RNA修饰及其效应因子可调控多种植物发育进程，但迄今为止，此类效应因子是否以及如何通过转录调控以赋予功能特异性，仍未明确。本研究证实，水稻C2H2锌指蛋白（C2H2 zinc finger protein）OsZAF可在水稻花药的小孢子发生（microsporogenesis）过程中，特异性激活编码m6A甲基转移酶复合物（m6A methyltransferase complex）核心组分的OsFIP37基因的表达。OsFIP37继而可促进花药中生长素（auxin）合成基因OsYUCCA3的m6A修饰与转录本稳定性，进而推动花药内生长素的生物合成。这一过程会提升生长素水平，同时伴随生长素响应因子（auxin response factor）OsARF12的表达上调；而OsARF12可正向调控OsZAF的表达，由此形成一条正反馈环路，使OsFIP37得以持续激活以维持局部生长素的合成。本研究结果表明，依赖OsZAF的m6A修饰反馈调控，是花药局部生长素生物合成与信号转导的核心环节，可保障水稻雄性减数分裂（male meiosis）所需的生长素峰值及时形成。