SlBES1 promotes tomato fruit softening through transcriptional inhibition of PMEU1

Haoran Liu; Lihong Liu; Dongyi Liang; Min Zhang; Chengguo Jia; Mingfang Qi; Yuanyuan Liu; Zhiyong Shao; Fanliang Meng; Songshen Hu; Yanhai Yin; Chuanyou Li; Qiaomei Wang

doi:10.1016/j.isci.2021.102926

SlBES1 promotes tomato fruit softening through transcriptional inhibition of PMEU1

iScience. 2021 Jul 30;24(8):102926. doi: 10.1016/j.isci.2021.102926. eCollection 2021 Aug 20.

Authors

Affiliations

¹ Key Laboratory of Horticultural Plant Growth and Development, Ministry of Agriculture, Department of Horticulture, Zhejiang University, Hangzhou 310058, PR China.
² College of Plant Science, Jilin University, Changchun, Jilin 130062, PR China.
³ Key Laboratory of Protected Horticulture of Ministry of Education, College of Horticulture, Shenyang Agricultural University, Shenyang 110866, PR China.
⁴ Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA.
⁵ State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100097, PR China.

Abstract

Fruit softening indicated by firmness determines the texture, transportability, and shelf life of tomato products. However, the regulatory mechanism underlying firmness formation in tomato fruit is poorly understood. Here, we report the regulatory role of SlBES1, an essential component of brassinosteroid hormone signaling, in tomato fruit softening. We found that SlBES1 promotes fruit softening during tomato fruit ripening and postharvest storage. RNA-seq analysis suggested that PMEU1, which encodes a pectin methylesterase, might participate in SlBES1-mediated softening. Biochemical and immunofluorescence assays indicated that SlBES1 inhibited PMEU1-related pectin de-methylesterification. Further molecular and genetic evidence verified that SlBES1 directly binds to the E-box of PMEU1 to repress its expression, leading to fruits softening. Loss-of-function SlBES1 mutant generated by CRISPR-Cas9 showed firmer fruits and longer shelf life during postharvest storage without other quality alteration. Collectively, our results indicated the potential of manipulating SlBES1 to regulate firmness without negative consequence on visual and nutrition quality.

Keywords: Biological sciences; Molecular biology; Plant biology; Plant development.