MiRNAs are important posttranscriptional regulators of plant development. Many miRNAs, such as the conserved miR164 species, are encoded by families of MIRNA genes, but the specific roles of individual MIRNA genes are largely undefined. Here, we characterize the functions and regulatory mechanisms of SlMIR164A, one of the primary genes of Sly-miR164, in tomato. We show that SlMIR164A is preferentially expressed at late stages of fruit development and plays a vital role in controlling fruit ripening and quality. Loss of function of SlMIR164A by CRISPR/Cas9-mediated mutagenesis results in accelerated fruit ripening and enhanced chloroplast development, which leads to altered sugar and organic acid contents and affects the nutritional quality of fruits. We also show that SlMIR164A modulates fruit ripening and quality through specific target genes, SlNAM2 and SlNAM3, which control key regulators of chloroplast function and fruit ripening processes. MIR164 genes have been shown to play conserved roles in regulating organ ageing, such as leaf senescence and fruit ripening, in a variety of plants, but whether and how their family members in tomato exert the same function remain to be elucidated. Our results reveal a previously undiscovered role of SlMIR164A in ripening control, which will further our understanding of the actions of MIR164 family, as well as the mechanisms of fruit ripening and quality control in tomato. Moreover, as loss of SlMIR164A exhibits minor impacts on organ morphology, our results can be leveraged in tomato breeding for specific manipulation of fruit ripening and quality to facilitate tomato improvement in agriculture.

中文翻译：

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SlMIR164A通过控制番茄中的SlNAM2和SlNAM3调控果实成熟和品质

miRNA是植物发育的重要转录后调节因子。许多 miRNA，例如保守的 miR164 物种，由MIRNA基因家族编码，但单个MIRNA基因的具体作用在很大程度上是不确定的。在这里，我们描述了番茄中 Sly-miR164 的主要基因之一SlMIR164A的功能和调控机制。我们表明，SlMIR164A在果实发育的后期优先表达，在控制果实成熟和品质方面起着至关重要的作用。SlMIR164A功能丧失通过 CRISPR/Cas9 介导的诱变导致果实加速成熟和叶绿体发育增强，从而导致糖和有机酸含量发生改变，影响果实的营养品质。我们还表明，SlMIR164A通过特定靶基因SlNAM2和SlNAM3调节果实成熟和品质，这些基因控制叶绿体功能和果实成熟过程的关键调节因子。MIR164基因已被证明在调节多种植物的器官衰老（如叶片衰老和果实成熟）中发挥保守作用，但它们在番茄中的家族成员是否以及如何发挥相同功能仍有待阐明。我们的结果揭示了SlMIR164A以前未被发现的作用在成熟控制方面，这将进一步了解MIR164家族的作用，以及番茄果实成熟和质量控制的机制。此外，由于SlMIR164A的损失对器官形态的影响较小，我们的结果可用于番茄育种，以对果实成熟和质量进行特定操作，以促进番茄在农业中的改良。