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Article|11 Jul 2019|OPEN
Auxin response factor 6A regulates photosynthesis, sugar accumulation, and fruit development in tomato
Yujin Yuan1 , Xin Xu1 , Zehao Gong1 , Yuwei Tang1 , Mengbo Wu1 , Fang Yan1 , Xiaolan Zhang1 , Qian Zhang2 , Fengqing Yang2 , Xiaowei Hu1 , Qichen Yang3 , Yingqing Luo1 , Lihua Mei1 , Wenfa Zhang1 , Cai-Zhong Jiang4,5 , Wangjin Lu6 and Zhengguo Li1 , Wei Deng,1 ,
1Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, 401331 Chongqing, China
2School of Chemistry and Chemical Engineering, Chongqing University, 400044 Chongqing, China
3College of Basic Science, Tianjin Agricultural University, 300384 Tianjin, China
4Department of Plant Sciences, University of California, Davis, CA 95616, USA
5Crops Pathology and Genetics Research Unit, United States Department of Agriculture, Agricultural Research Service, Davis, CA 95616, USA
6State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, College of Horticulture, South China Agricultural University, 510642 Guangzhou, China
*Corresponding author. E-mail: dengwei1977@cqu.edu.cn

Horticulture Research 6,
Article number: 85 (2019)
doi: https://doi.org/10.1038/s41438-019-0167-x
Views: 1034

Received: 14 May 2019
Revised: 17 May 2019
Accepted: 17 May 2019
Published online: 11 Jul 2019

Abstract

Auxin response factors (ARFs) are involved in auxin-mediated transcriptional regulation in plants. In this study, we performed functional characterization of SlARF6A in tomato. SlARF6A is located in the nucleus and exhibits transcriptional activator activity. Overexpression of SlARF6A increased chlorophyll contents in the fruits and leaves of tomato plants, whereas downregulation of SlARF6A decreased chlorophyll contents compared with those of wild-type (WT) plants. Analysis of chloroplasts using transmission electron microscopy indicated increased sizes of chloroplasts in SlARF6A-overexpressing plants and decreased numbers of chloroplasts in SlARF6A-downregulated plants. Overexpression of SlARF6A increased the photosynthesis rate and accumulation of starch and soluble sugars, whereas knockdown of SlARF6A resulted in opposite phenotypes in tomato leaves and fruits. RNA-sequence analysis showed that regulation of SlARF6A expression altered the expression of genes involved in chlorophyll metabolism, photosynthesis and sugar metabolism. SlARF6A directly bound to the promoters of SlGLK1, CAB, and RbcS genes and positively regulated the expression of these genes. Overexpression of SlARF6A also inhibited fruit ripening and ethylene production, whereas downregulation of SlARF6A increased fruit ripening and ethylene production. SlARF6A directly bound to the SAMS1 promoter and negatively regulated SAMS1 expression. Taken together, these results expand our understanding of ARFs with regard to photosynthesis, sugar accumulation and fruit development and provide a potential target for genetic engineering to improve fruit nutrition in horticulture crops.