Gibberellins (GAs) play crucial roles in a wide range of developmental processes and stress responses in plants. However, the roles of GA-responsive genes in tomato (Solanum lycopersicum) fruit development remain largely unknown. Here, we identify 17 GASA (Gibberellic Acid-Stimulated Arabidopsis) family genes in tomato. These genes encode proteins with a cleavable signal peptide at their N terminus and a conserved GASA domain at their C terminus. The expression levels of all tomato GASA family genes were responsive to exogenous GA treatment, but adding ethylene eliminated this effect. Comprehensive expression profiling of SlGASA family genes showed that SlGASA1 follows a ripening-associated expression pattern, with low expression levels during fruit ripening, suggesting it plays a negative role in regulating ripening. Overexpressing SlGASA1 using a ripening-specific promoter delayed the onset of fruit ripening, whereas SlGASA1-knockdown fruits displayed accelerated ripening. Consistent with their delayed ripening, SlGASA1-overexpressing fruits showed significantly reduced ethylene production and carotenoid contents compared to the wild type. Moreover, ripening-related genes were downregulated in SlGASA1-overexpressing fruits but upregulated in SlGASA1-knockdown fruits compared to the wild type. Yeast two-hybrid, co-immunoprecipitation, transactivation, and DNA pull-down assays indicated that SlGASA1 interacts with the key ripening regulator FRUITFULL1 and represses its activation of the ethylene biosynthesis genes ACS2 and ACO1. Our findings shed new light on the role and mode of action of a GA-responsive gene in tomato fruit ripening.

中文翻译：

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番茄 GASA 家族的全基因组表征将 SlGASA1 鉴定为果实成熟的阻遏物

赤霉素 (GAs) 在植物的广泛发育过程和胁迫反应中起着至关重要的作用。然而，GA 反应基因在番茄 (Solanum lycopersicum) 果实发育中的作用在很大程度上仍然未知。在这里，我们鉴定了番茄中的 17 个 GASA（赤霉酸刺激的拟南芥）家族基因。这些基因编码的蛋白质在其 N 末端具有可切割的信号肽，在其 C 末端具有保守的 GASA 结构域。所有番茄 GASA 家族基因的表达水平都对外源 GA 处理有反应，但添加乙烯消除了这种影响。SlGASA家族基因的综合表达谱表明，SlGASA1遵循成熟相关的表达模式，在果实成熟过程中表达量较低，表明其在调控成熟中起着负作用。使用成熟特异性启动子过表达 SlGASA1 会延迟果实成熟的开始，而 SlGASA1 敲低的果实则显示加速成熟。与它们的延迟成熟一致，与野生型相比，SlGASA1 过表达的果实显示出乙烯产量和类胡萝卜素含量显着降低。此外，与野生型相比，成熟相关基因在 SlGASA1 过表达果实中下调，但在 SlGASA1 敲低果实中上调。酵母双杂交、免疫共沉淀、反式激活和 DNA 下拉分析表明，SlGASA1 与关键的成熟调节剂 FRUITFULL1 相互作用，并抑制其对乙烯生物合成基因 ACS2 和 ACO1 的激活。我们的研究结果揭示了 GA 反应基因在番茄果实成熟中的作用和作用模式。