CsCYP82D47 Is Identified as a Candidate Gene for Vivipary in Cucumber (Cucumis sativus L.).

Vivipary adversely affects the production process of the cucumber seed industry and greatly limits the popularization of cucumber varieties. Identification of the cucumber seed vivipary phenotype and screening of vivipary-associated genes will provide important theoretical value and practical significance for solving this problem in agricultural production. In this study, cucumber near-isogenic lines with significant differences in vivipary traits (viviparous line F and non-viviparous line BF) were successfully screened and used to construct genetic populations. Bulk segregant analysis (BSA) and QTL-seq were performed to fine-map the major-effect quantitative trait locus associated with vivipary variation. Based on QTL and BSA analyses, CsaV3_3G044640 (designated CsCYP82D47), which encodes a cytochrome P450 family protein, was identified as a candidate gene associated with cucumber vivipary. CsCYP82D47 exhibits obvious tissue specificity and is highly expressed in leaves, sprouts, and seeds. However, no significant difference in CsCYP82D47 expression was detected between viviparous and non-viviparous cucumber materials. Further sequence analysis revealed multiple mutation sites in this gene between different genotypes. Specifically, the CYP82D47 protein in viviparous materials harbours one amino acid insertion (L63) and two missense mutations (M71L and S124L). In addition, the altered leucine residue distribution in viviparous cucumber may enlarge the substrate channel and enhance substrate catalytic efficiency, which may contribute to the vivipary phenotype. In summary, this study identifies a promising candidate gene potentially related to cucumber vivipary, which lays a foundation for further exploration of the molecular mechanism underlying cucumber vivipary and provides a potential genetic resource for cucumber molecular breeding.