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Article|06 Sep 2022|OPEN
VvSUN may act in the auxin pathway to regulate fruit shape in grape
Huan Zheng1 , Yang Dong1 , Huilan Nong1 , Liyuan Huang1 , Jing Liu1 , Xin Yu1 , Yaguan Zhang1 , Lina Yang2 , Ben Hong1 , Wu Wang3 and Jianmin Tao,1 ,
1College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
2Charles River Laboratories International, Inc., Michigan, 49071, USA
3Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing 210014, China
*Corresponding author. E-mail: taojianmin@njau.edu.cn

Horticulture Research 9,
Article number: uhac200 (2022)
doi: https://doi.org/10.1093/hr/uhac200
Views: 109

Received: 17 Apr 2022
Accepted: 31 Aug 2022
Published online: 06 Sep 2022

Abstract

Fruit shape is an essential agronomic feature in many crops. We identified and functionally characterized an auxin pathway-related gene, VvSUNVvSUN, which belongs to the SUN/IQ67-DOMAIN (IQD) family, localizes to the plasma membrane and chloroplast and may be involved in controlling fruit shape through auxin. It is highly expressed in the ovary, and the expression level 1 week before the anthesis stage is positively correlated with the fruit shape index. Functional analyses illustrated that VvSUN gene overexpression in tomato and tobacco plants changed fruit/pod shape. The VvSUN promoter directly bound to VvARF6 in yeast and activated ß-glucuronidase (GUS) activity by indole-3-acetic acid (IAA) treatments in grapevine leaves, indicating that VvSUN functions are in coordination with auxin. Further analysis of 35S::VvSUN transgenic tomato ovaries showed that the fruit shape changes caused by VvSUN were predominantly caused by variations in cell number in longitudinal directions by regulating endogenous auxin levels via polar transport and/or auxin signal transduction process variations. Moreover, enrichment of the 35S::VvSUN transgenic tomato differentially expressed genes was found in a variety of biological processes, including primary metabolic process, transmembrane transport, calcium ion binding, cytoskeletal protein binding, tubulin binding, and microtubule-based movement. Using weighted gene co-expression network analysis (WGCNA), we confirmed that this plant hormone signal transduction may play a crucial role in controlling fruit shape. As a consequence, it is possible that VvSUN acts as a hub gene, altering cellular auxin levels and the plant hormone signal transduction pathway, which plays a role in cell division patterns, leading to anisotropic growth of the ovary and, ultimately, an elongated fruit shape.