National Key Laboratory of Rice Biology and Zhejiang Provincial Key Laboratory of Crop Germplasm Resources, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
Hainan Yazhou Bay Seed Laboratory, Hainan Institute, Zhejiang University, Sanya, Hainan, 572000, China.
Nat Commun. 2024 Mar 21;15(1):2525. doi: 10.1038/s41467-024-46765-z.
MicroRNAs (miRNAs) play fundamental roles in many developmental and physiological processes in eukaryotes. MiRNAs in plants generally regulate their targets via either mRNA cleavage or translation repression; however, which approach plays a major role and whether these two function modes can shift remains elusive. Here, we identify a miRNA, miR408-5p that regulates AUXIN/INDOLE ACETIC ACID 30 (IAA30), a critical repressor in the auxin pathway via switching action modes in rice. We find that miR408-5p usually inhibits IAA30 protein translation, but in a high auxin environment, it promotes the decay of IAA30 mRNA when it is overproduced. We further demonstrate that IDEAL PLANT ARCHITECTURE1 (IPA1), an SPL transcription factor regulated by miR156, mediates leaf inclination through association with miR408-5p precursor promoter. We finally show that the miR156-IPA1-miR408-5p-IAA30 module could be controlled by miR393, which silences auxin receptors. Together, our results define an alternative auxin transduction signaling pathway in rice that involves the switching of function modes by miR408-5p, which contributes to a better understanding of the action machinery as well as the cooperative network of miRNAs in plants.
微小 RNA（miRNA）在真核生物的许多发育和生理过程中发挥着基本作用。植物中的 miRNA 通常通过 mRNA 切割或翻译抑制来调节其靶标；然而，哪种方法起主要作用以及这两种功能模式是否可以转变仍不清楚。在这里，我们鉴定了一个 miRNA，miR408-5p，它通过在水稻中切换作用模式来调节生长素/吲哚乙酸 30（IAA30），这是生长素途径中的一个关键抑制剂。我们发现 miR408-5p 通常抑制 IAA30 蛋白的翻译，但在高生长素环境中，当 IAA30 过量产生时，它会促进 IAA30 mRNA 的降解。我们进一步证明，理想植物结构 1（IPA1），一种受 miR156 调控的 SPL 转录因子，通过与 miR408-5p 前体启动子结合来介导叶片倾斜。我们最后表明，miR156-IPA1-miR408-5p-IAA30 模块可以被 miR393 控制，miR393 沉默生长素受体。总之，我们的结果定义了一个水稻中替代的生长素转导信号通路，其中 miR408-5p 通过功能模式的切换来参与，这有助于更好地理解植物中 miRNA 的作用机制以及协同网络。
