Genome-wide characterization of the tomato GASA family identifies SlGASA1 as a repressor of fruit ripening.

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 () fruit development remain largely unknown. Here, we identify 17 () 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 family genes were responsive to exogenous GA treatment, but adding ethylene eliminated this effect. Comprehensive expression profiling of family genes showed that follows a ripening-associated expression pattern, with low expression levels during fruit ripening, suggesting it plays a negative role in regulating ripening. Overexpressing using a ripening-specific promoter delayed the onset of fruit ripening, whereas -knockdown fruits displayed accelerated ripening. Consistent with their delayed ripening, -overexpressing fruits showed significantly reduced ethylene production and carotenoid contents compared to the wild type. Moreover, ripening-related genes were downregulated in -overexpressing fruits but upregulated in -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 and . Our findings shed new light on the role and mode of action of a GA-responsive gene in tomato fruit ripening.