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Article|28 Sep 2022|OPEN
Genome-wide characterization of the tomato GASA family identifies SlGASA1 as a repressor of fruit ripening 
Dan Su1,5 , Kaidong Liu2,5 , Zhuoshu Yu1 , Ying Li1 , Yaoxin Zhang1 , Yunqi Zhu1 , Yi Wu1 , Hongyu He3 , Xiaodan Zeng3 , Honglin Chen3 and Don Grierson4 , Heng Deng1 , , Mingchun Liu,1 ,
1Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, Sichuan, China
2Life Science and Technology School, Lingnan Normal University, Zhanjiang 524048, China
3Institute of Agro-Products Processing Science and Technology, Sichuan Academy of Agricultural Sciences, Chengdu 610066, China
4School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, United Kingdom
5Dan Su and Kaidong Liu contributed equally
*Corresponding author. E-mail: dengheng@scu.edu.cn,mcliu@scu.edu.cn

Horticulture Research 10,
Article number: uhac222 (2023)
doi: https://doi.org/10.1093/hr/uhac222
Views: 442

Received: 15 Feb 2022
Accepted: 22 Sep 2022
Published online: 28 Sep 2022

Abstract

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.