The N⁶-methyladenosine (m⁶A) mRNA modification is crucial for plant development and stress responses. In rice, the male sterility resulting from the deficiency of OsFIP37, a core component of m⁶A methyltransferase complex, emphasizes the significant role of m⁶A in male fertility. m⁶A is reversible and can be removed by m⁶A demethylases. However, whether mRNA m⁶A demethylase regulates male fertility in rice has remained unknown. Here, we identify the mRNA m⁶A demethylase OsALKBH9 and demonstrate its involvement in male fertility regulation. Knockout of OsALKBH9 causes male sterility, dependent on its m⁶A demethylation activity. Cytological analysis reveals defective tapetal programmed cell death (PCD) and excessive accumulation of microspores exine in Osalkbh9-1. Transcriptome analysis of anthers shows up-regulation of genes involved in tapetum development, sporopollenin synthesis, and transport pathways in Osalkbh9-1. Additionally, we demonstrate that OsALKBH9 demethylates the m⁶A modification in TDR and GAMYB transcripts, which affects the stability of these mRNAs and ultimately leads to excessive accumulation of pollen exine. Our findings highlight the precise control of mRNA m⁶A modification and reveal the pivotal roles played by OsALKBH9-mediated m⁶A demethylation in tapetal PCD and pollen exine accumulation in rice.

中文翻译：

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OsALKBH9 介导的 m6A 去甲基化调节水稻绒毡层 PCD 和花粉外壁积累

N ⁶ -甲基腺苷 (m ⁶ A) mRNA 修饰对于植物发育和胁迫反应至关重要。在水稻中，由于 OsFIP37（m ⁶ A 甲基转移酶复合物的核心成分）缺乏而导致雄性不育，强调了 m ⁶ A 在雄性育性中的重要作用。 m ⁶ A 是可逆的，可以通过 m ⁶ A 去甲基酶去除。然而，mRNA m ⁶ A 去甲基化酶是否调节水稻雄性育性仍不清楚。在这里，我们鉴定了 mRNA m ⁶ A 去甲基化酶 OsALKBH9 并证明其参与男性生育力调节。OsALKBH9的敲除会导致雄性不育，这取决于其 m ⁶ A 去甲基化活性。细胞学分析揭示了Osalkbh9-1中绒毡层程序性细胞死亡 (PCD) 缺陷和小孢子外壁过度积累。花药的转录组分析显示Osalkbh9-1中参与绒毡层发育、孢粉质合成和运输途径的基因上调。此外，我们证明 OsALKBH9 使TDR和GAMYB转录本中的m ⁶ A修饰去甲基化，从而影响这些 mRNA 的稳定性，并最终导致花粉外壁过度积累。我们的研究结果强调了 mRNA m ⁶ A 修饰的精确控制，并揭示了 OsALKBH9 介导的 m ⁶ A 去甲基化在水稻绒毡层 PCD 和花粉外壁积累中发挥的关键作用。