SRA

Cucumber fruit wart composed of spine and tubercule is an important appearance quality trait, which affects product classification and market value of cucumber fruit. Although several key genes for initiation and development of spine and tubercule have been cloned, their underlying mechanisms and relationships have not been well studied. Here, we identified a cucumber basic Helix-Loop-Helix (bHLH) gene CsHEC2 that was strongly expressed in spines and tubercules of cucumber peel. Knockout lines obtained using CRISPR/Cas9 technology were used to explore the biological function of CsHEC2. Compared with the wild type, the Cshec2 mutants resulted in reduced density of wart, and decreased cytokinin accumulation in fruit peel compared to wild type. To comprehensively analyze the regulatory network, RNA sequencing (RNA-seq) experiments were conducted on female buds at 7 days before anthesis (DBA). Transcriptomic data analysis showed that 293 and 1295 genes were up- and down-regulated in Cshec2 mutants relative to WT, respectively. Several sets of genes for cytokinin biosynthesis and metabolism were expressed differently, which explained the decrease of cytokinin in Cshec2 mutants. Our results suggested that CsHEC2 is very likely to regulate the initiation of fruit wart by affecting cytokinin pathway. Overall design: RNA sequencing experiments were performed using the female buds at 7 days before anthesis. Samples were obtained from WT and Cshec2 mutant lines, and three biological replicates were set for each sample.