Genome-Wide Analysis of Exocyst Complex Subunit Exo70 Gene Family in Cucumber

Cucumber (Cucumis sativus L.) is an important vegetable worldwide, but its yield is affected by a wide range of pathogens and pests. As the major subunit of the exocyst complex, the roles of Exo70 members have been shown in Arabidopsis and rice, but their function are unknown in cucumber. Here, we identified 18 CsExo70 members in cucumber, which were divided into three groups (Exo70.1-Exo70.3) and nine subgroups (Exo70A-Exo70I) based on the phylogenetic tree. Subsequently, systematical analyses were performed, including collinearity, gene structure, cis-acting elements, conserved motifs, expression patterns, and subcellular localization. Our results showed that CsExo70 genes were generally expressed in all tissues, and CsExo70C1 and CsExo70C2 were highly expressed in the stamen. Moreover, the expression levels of most CsExo70 genes were induced by Pseudomonas syringae pv. lachrymans (Psl) and Fusarium oxysporum f. sp. cucumerinum Owen (Foc), especially CsExo70E2 and CsExo70H3. In addition, these CsExo70s displayed similar location patterns with discrete and punctate signals in the cytoplasm. Together, our results indicate that CsExo70 members may be involved in plant development and resistance, and provide a reference for future in-depth studies of Exo70 genes in cucumber.