Comprehensive identification of the VQ family genes in cucumber and their roles in response to abiotic and biotic stresses

Valine-glutamine (VQ) motif-containing proteins are plant-specific transcription factors with critical functions plant growth, development and defense reactions. However, no systematic study has been performed for family genes in cucumber to date. In this work, a total of 32 VQ family genes (CsVQ1-CsVQ32) were identified cucumber, which were unevenly distributed on seven cucumber chromosomes (chromosomes 1-7). The were divided into nine distinct groups (group I-IX) according to their phylogenetic relationships, with members of the same group sharing highly conserved motif compositions. Gene structure analysis suggested the CsVQ genes were generally lack of introns. Gene duplication analysis revealed that two and 11 CsVQ were located in the tandem and segmental duplication regions of cucumber chromosomes, respectively. Tissue expression profiles obtained from RNA-seq data showed that most CsVQ genes were differentially expressed different tissues and developmental stages. Quantitative real-time PCR (qRT-PCR) of six selected CsVQ (CsVQ6, CsVQ9, CsVQ12, CsVQ13, CsVQ16 and CsVQ20) showed that all of them were regulated by cold, drought and salt stresses. In addition, RNA-seq analysis revealed changes in the expression of some CsVQ genes (such CsVQ2, CsVQ9, CsVQ12, CsVQ13, CsVQ20 and CsVQ22) under downy mildew (DM) and powdery mildew treatments. Our findings provide a theoretical basis for studying the potential roles of CsVQ genes development and stress response of cucumber in the future.& nbsp;& nbsp;