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Article|01 Dec 2022|OPEN
Identification and characterization of CsSRP43, a major gene controlling leaf yellowing in cucumber
Tingting Zhang1,2 , Xiangyu Dong1,2 , Xin Yuan1,2 and Yuanyuan Hong1,2 , Lingling Zhang1,2 , Xuan Zhang1,2 , Shuxia Chen,1,2 ,
1College of Horticulture, Northwest A&F University, Yangling 712100, Shaanxi, China
2Shaanxi Engineering Research Center for Vegetables, Yangling 712100, China
*Corresponding author. E-mail: shuxiachen@nwsuaf.edu.cn

Horticulture Research 9,
Article number: uhac212 (2022)
doi: https://doi.org/10.1093/hr/uhac212
Views: 217

Received: 18 May 2022
Accepted: 14 Sep 2022
Published online: 01 Dec 2022

Abstract

Mutants are crucial to extending our understanding of genes and their functions in higher plants. In this study a spontaneous cucumber mutant, yf, showed yellow color leaves, had significant decreases in related physiological indexes of photosynthesis characteristics, and had more abnormal chloroplasts and thylakoids. Inheritance analysis indicated that the yellow color of the leaf was controlled by a recessive nuclear locus, yf. A candidate gene, CsSRP43, encoding a chloroplast signal recognition particle 43 protein, was identified through map-based cloning and whole-genome sequence analysis. Alignment of the CsSRP43 gene homologs between both parental lines revealed a 7-kb deletion mutation including the promoter region and the coding sequence in the yf mutant. In order to determine if the CsSRP43 gene was involved in the formation of leaf color, the CRISPR/Cas9-mediate system was used to modify CsSRP43 in the 9930 background; two independent transgenic lines, srp43-1 and srp43-2, were generated, and they showed yellow leaves with abnormal chloroplasts and thylakoids. Transcriptomic analysis revealed that differentially expressed genes associated with the photosynthesis-related pathway were highly enriched between srp43-1 and wild type, most of which were significantly downregulated in line srp43-1. Furthermore, yeast two-hybrid and biomolecular fluorescence complementation assays were used to confirm that CsSRP43 directly interacted with LHCP and cpSRP54 proteins. A model was established to explain the molecular mechanisms by which CsSRP43 participates in the leaf color and photosynthesis pathway, and it provides a valuable basis for understanding the molecular and genetic mechanisms of leaf color in cucumber.