Light plays a critical role in plant growth and development, but the mechanisms through which light regulates fruit ripening and nutritional quality in horticultural crops remain largely unknown. Here, we found that ELONGATED HYPOCOTYL 5 (HY5), a master regulator in the light signaling pathway, is required for normal fruit ripening in tomato (Solanum lycopersicum). Loss of function of tomato HY5 (SlHY5) impairs pigment accumulation and ethylene biosynthesis. Transcriptome profiling identified 2948 differentially expressed genes, which included 1424 downregulated and 1524 upregulated genes, in the Slhy5 mutants. In addition, genes involved in carotenoid and anthocyanin biosynthesis and ethylene signaling were revealed as direct targets of SlHY5 by chromatin immunoprecipitation. Surprisingly, the expression of a large proportion of genes encoding ribosomal proteins was downregulated in the Slhy5 mutants, and this downregulation pattern was accompanied by a decrease in the abundance of ribosomal proteins. Further analysis demonstrated that SlHY5 affected the translation efficiency of numerous ripening-related genes. These data indicate that SlHY5 regulates fruit ripening both at the transcriptional level by targeting specific molecular pathways and at the translational level by affecting the protein translation machinery. Our findings unravel the regulatory mechanisms of SlHY5 in controlling fruit ripening and nutritional quality and uncover the multifaceted regulation of gene expression by transcription factors.

中文翻译：

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转录因子 SlHY5 在转录和翻译水平上调节番茄果实的成熟

光在植物生长和发育中起着至关重要的作用，但光在园艺作物中调节果实成熟和营养质量的机制在很大程度上仍是未知的。在这里，我们发现 ELONGATED HYPOCOTYL 5 (HY5) 是光信号通路中的主要调节因子，是番茄果实正常成熟所必需的。番茄）。番茄功能丧失HY5(SLHY5) 损害色素积累和乙烯生物合成。转录组分析确定了 2948 个差异表达基因，其中包括 1424 个下调和 1524 个上调基因，在SLHY5突变体。此外，通过染色质免疫沉淀，发现参与类胡萝卜素和花青素生物合成和乙烯信号传导的基因是 SlHY5 的直接靶标。令人惊讶的是，大部分编码核糖体蛋白的基因的表达在SLHY5突变体，并且这种下调模式伴随着核糖体蛋白丰度的减少。进一步的分析表明，SlHY5 影响了许多成熟相关基因的翻译效率。这些数据表明，SlHY5 通过靶向特定分子途径在转录水平和通过影响蛋白质翻译机制在翻译水平调节果实成熟。我们的研究结果揭示了 SlHY5 在控制果实成熟和营养质量方面的调控机制，并揭示了转录因子对基因表达的多方面调控。