Villin Family Members Associated with Multiple Stress Responses in Cotton

Villin (VLN) is considered to be one of the most important actin-binding proteins, participates in modulating the actin cytoskeleton dynamics, plays essential role in plant development and resisting adverse environments. However, systematic studies of the VLN gene family have not been reported in cotton (Gossypium). In this study, 14 GhVLNs were identified in G. hirsutum. These GhVLN genes were distributed in 6 A-subgenome chromosomes and 6 D-subgenome chromosomes of the allotetraploid upland cotton and classified into three phylogenetical groups based on the classification model of AtVLNs. In addition, the 14 GhVLN genes have highly conserved gene structure and motif architecture. The number of introns was ranged from 18 to 22 and the length of protein sequences was varied from 901 to 1077. Six gelsolin homology domains, G1–G6, and villin headpiece domain, VHP, were existed in all GhVLNs with the exception of two VLNs (GhVLN6 and GhVLN13) which lacked VHP. Cis-elements analysis revealed that the promoter regions of GhVLNs contained various light related components and also elements responsible for phytohormones and stresses response, indicating that, when subjected to those adverse environments, cotton plants may activate the response system by targeting VLN genes to survive the crisis. Heatmaps showed that the GhVLN genes exhibited various expression patterns, some were accumulated in certain tissues, root, petal, stamen or elongating fibers, and some were obviously induced by environmental changes. Especially GhVLN3 and GhVLN10 were highly and preferentially expressed in elongating fibers and distinctly upregulated by abiotic (salt, PEG, cold and heat) and biotic (Verticillium dahliae V991) stresses. This study may provide useful information for biological function identification of GhVLN genes and gene resources for creating high-quality and various resistant cotton germplasms.