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Article|26 May 2022|OPEN
Regulation of tomato fruit elongation by transcription factor BZR1.7 through promotion of SUN gene expression 
Ting Yu1 , Guo Ai1 , Qingmin Xie1 , Wenqian Wang1 , Jianwen Song1 , Jiaying Wang1 , Jingbao Tao1 , Xingyu Zhang1 , Zonglie Hong2 , Yongen Lu1 , Jie Ye1 , Yuyang Zhang1 , Junhong Zhang1 , and Zhibiao Ye,1 ,
1Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan 430070, China
2Department of Plant Sciences, University of Idaho, Moscow, ID 83844, USA
*Corresponding author. E-mail:,

Horticulture Research 9,
Article number: uhac121 (2022)
Views: 110

Received: 03 Dec 2021
Accepted: 15 May 2022
Published online: 26 May 2022


Fruit shape is an important biological trait that is also of special commercial value in tomato. The SUN gene has been known as a key regulator of tomato fruit elongation for years, but the molecular mechanisms underlying its transcriptional regulation remain little understood. Here, a unique BZR1-like transcription factor, BZR1.7, was identified as a trans-acting factor of the SUN gene promoter that bound to the conserved E-box of the promoter to promote SUN gene expression. Overexpression of BZR1.7 in tomato led to elevated SUN gene expression and formation of elongated fruits. Plants of the BZR1.7 knockout mutant created by gene editing did not exhibit an observable fruit shape phenotype, suggesting possible functional redundancy of BZR1-like genes in tomato. There were seven BZR1-like genes in the tomato genome and overexpression of BZR1.5 and BZR1.6 led to elongated fruit phenotypes similar to those observed in the BZR1.7 overexpression lines, further supporting the notion of functional redundancy of BZR1-like genes in tomato fruit shape specification. Microscopic analysis revealed that there was a decreased number of cell layers in the fruit pericarp in the BZR1.7 overexpression lines. These findings offer new insights into the regulatory mechanism by which BZR1.7 promotes SUN gene expression and regulates fruit elongation in tomato.