MicroRNAs (miRNAs) play important roles in various cellular growth and developmental processes through post-transcriptional gene regulation via mRNA cleavage and degradation and the inhibition of protein translation. To explore if miRNAs play a role in appressoria formation and virulence that are also governed by the regulators of G-protein signaling (RGS) proteins in the rice blast fungus Magnaporthe oryzae, we have compared small RNA (sRNA) production between several ΔMorgs mutant and the wild-type strains. We have identified sRNA236 as a microRNA-like milR236 that targets the encoding sequence of MoHat1, a histone acetyltransferase type B catalytic subunit involved in appressorium function and virulence. We have also found that milR236 overexpression induces delayed appressorium formation and virulence attenuation, similar to those displayed by the ΔMohat1 mutant strain. Moreover, we have shown that the transcription factor MoMsn2 binds to the promoter sequence of milR236 to further suppress MoHAT1 transcription and MoHat1-regulated appressorium formation and virulence. In summary, by identifying a novel regulatory role of sRNA in the blast fungus, our studies reveal a new paradigm in the multifaceted regulatory pathways that govern the appressorium formation and virulence of M. oryzae.

中文翻译：

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受转录因子 MoMsn2 调节的 MicroRNA 样 milR236 靶向组蛋白乙酰转移酶 MoHat1，在稻瘟病真菌稻瘟病菌的附着胞形成和毒力中发挥作用。

MicroRNAs (miRNAs) 通过 mRNA 切割和降解的转录后基因调控以及蛋白质翻译的抑制，在各种细胞生长和发育过程中发挥重要作用。为了探索 miRNA 在附着胞形成和毒力中是否发挥作用，而这些也受稻瘟病真菌稻瘟病菌中 G 蛋白信号 (RGS) 蛋白的调节因子控制，我们比较了几种 ΔMorgs 突变体和野生型菌株。我们已将 sRNA236 鉴定为一种类似 microRNA 的 milR236，其靶向 MoHat1 的编码序列，MoHat1 是一种参与附着胞功能和毒力的组蛋白乙酰转移酶 B 型催化亚基。我们还发现 milR236 过表达诱导附着胞形成延迟和毒力减弱，与 ΔMohat1 突变株显示的相似。此外，我们已经证明转录因子 MoMsn2 与 milR236 的启动子序列结合以进一步抑制 MoHAT1 转录和 MoHat1 调节的附着胞形成和毒力。总之，通过确定 sRNA 在稻瘟病菌中的一种新的调控作用，我们的研究揭示了控制稻瘟病菌附着胞形成和毒力的多方面调控途径的新范式。