Genome-wide identification of VOZ gene family in ten cotton species and the function analysis of GhVOZ2 involved in heat stress response.

BACKGROUND

Vascular plant one zinc-finger protein (VOZ) is a type of special transcription factor and plays important roles in regulating various biological processes in plants. However, a genome-wide analysis of VOZ gene family in cotton is still not clear, which greatly limits the further understanding of VOZ gene function and regulatory mechanism.

RESULTS

We identified 44 VOZ family genes in ten cotton species including 3 in Gossypium herbaceum, G. arboretum, G. thurberi, and G. Raimondii, 6 in G. hirsutum, G. barbadense, G. tomentosum, and G. mustelinum, and 5 in G. darwinii. The phylogenetic tree analysis indicated that VOZ gene family was subdivided into four subgroups. Chromosome location and collinearity analysis revealed that this gene family had experienced segment duplication events. The exon-intron structure and conserved motif analysis showed high conservations in each branch of the cotton VOZ genes. Cis-acting element component analysis displayed that VOZ gene family may be involved in various stresses. Expression profile analysis of GhVOZ genes through both publicly available RNA-seq data from G. hirsutum and quantitative reverse transcription PCR (RT-qPCR) indicated that GhVOZ members are involved in tissue development and biotic and abiotic responses, especially GhVOZ2 showed continuous high expressions in different tissues and stress treatments, with the most significantly induced accumulation under heat stress. Suppressing GhVOZ2 expression in virus-induced silencing (VIGS) cotton lines significantly decreased the tolerance to heat stress. Further RNA-seq analysis of TRV::GhVOZ2 showed that the down-regulated differentially expressed genes (DEGs) were mainly enriched in hormone signal pathways (auxin and BRs), phenylpropanoid and flavonoid biosynthesis, fatty acid elongation, starch and sucrose metabolism pathways, suggesting their potential important roles in heat response mediated by GhVOZ2.

CONCLUSIONS

A total of 44 VOZ genes were obtained in ten cotton species, and GhVOZ2 might perform significant positive function in cotton in response to heat stress via regulating the pathways of hormone signal and metabolisms. Our results provide insights into the function and regulatory mechanism of VOZ gene family and the further utilization of excellent cotton material breeding.