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

Abstract

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.

The exocyst subunit CsExo70B promotes both fruit length and disease resistance via regulating receptor kinase abundance at plasma membrane in cucumber

“…Previous studies showed that Exo70B members are involved in immunity by regulating the accumulation of RK‐FLS2 at PM in Arabidopsis (Wang et al ., 2020a ). To explore whether Exo70B regulates plant development by associating with RKs, we identified the Exo70B in cucumber ( CsaV3_1G036490 ) and named as CsExo70B hereinafter (Liu et al ., 2023 ). CRISPR/Cas9 method was used to generate Csexo70b knockout mutants.…”

“…Our results showed that CsERECTA was specifically highly expressed in fruit, while both CsFLS2 and CsLYK5 were significantly lower expressed in fruit than other tissues (Figure S13 ). When infected by pathogens, the expression levels of CsExo70B (Liu et al ., 2023 ) and immune RKs ( CsFLS2 and CsLYK5 ) were significantly up‐regulated, but the expression of CsERECTA was markedly down‐regulated in roots and leaves rather than fruits (Figures S14 and S15 ). So, one possibility is that CsExo70B may preferentially promote CsERECTA accumulation in fruit to regulate fruit elongation; while CsExo70B may have a prior choice to traffic more immune RKs to PM to activate stronger defence in roots and leaves upon pathogen attack.…”