Genome-Wide Identification of the DUF668 Gene Family in Cotton and Expression Profiling Analysis of GhDUF668 in Gossypium Hirsutum Under Adverse Stress

Abstract

Background: Domain of unknown function 668 (DUF668) may play a crucial role in the plant growth and developmental response to adverse stress. However, our knowledge of the function of the DUF668 gene family is limited.Results: Our study was conducted based on the DUF668 gene family identified from cotton genome sequencing. Phylogenetic analysis showed that the DUF668 family genes can be classified into four subgroups in cotton. We identified 32 DUF668 genes, which are distributed on 17 chromosomes and are mostly located in the nucleus of Gossypium hirsutum. Gene structure and motif analyses revealed that the members of the DUF668 gene family can be clustered in G. hirsutum into two broad groups, which are relatively evolutionarily conserved. Transcriptome data analysis showed that the GhDUF668 genes are differentially expressed in different tissues under various stresses (cold, heat, drought, salt, and Verticillium dahliae), and expression is generally increased in roots and stems. Promoter and expression analyses indicated that Gh_DUF668-05, Gh_DUF668-08, Gh_DUF668-11, Gh_DUF668-23 and Gh_DUF668-28 in G. hirsutum might have evolved resistance to adverse stress. Additionally, qRT-PCR revealed that these 5 genes in four cotton lines, KK1543 (drought resistant), Xinluzao 26 (drought sensitive), Zhongzhimian 2 (disease resistant) and Simian 3 (susceptible), under drought and Verticillium wilt stress were all significantly induced. Roots had the highest expression of these 5 genes before and after the treatment. Among them, the expression levels of Gh_DUF668-08 and Gh_DUF668-23 increased sharply at 6 h and reached a maximum at 12 h under biotic and abiotic stress, which showed that they might be involved in the process of adverse stress resistance in cotton.Conclusion: The significant changes in GhDUF668 expression in the roots after adverse stress indicate that GhDUF668 is likely to increase plant resistance to stress. This study provides an important theoretical basis for further research on the function of the DUF668 gene family and the molecular mechanism of adverse stress resistance in cotton.