Genome-wide analysis of GRAS transcription factor gene family in Gossypium hirsutum L.

Background: Cotton is a major fiber and oil crop worldwide. Cotton production, however, is often threatened by abiotic environmental stresses. GRAS family proteins are among the most abundant transcription factors in plants and play important roles in regulating root and shoot development, which can improve plant resistance to abiotic stresses. However, few studies on the GRAS family have been conducted in cotton. Recently, the G. hirsutum genome sequences have been released, which provide us an opportunity to analyze the GRAS family in G. hirsutum. Results: In total, 150 GRAS proteins from G. hirsutum were identified. Phylogenetic analysis showed that these GRAS protins could be classified into 14 subfamilies including SCR, DLT, OS19, LAS, SCL4/7, OS4, OS43, DELLA, PAT1, SHR, HAM, SCL3, LISCL and G_GRAS. The gene structure and motif distribution analysis of the GRAS members in G. hirsutum revealed that many genes of the SHR subfamily have more than one intron, which maybe a kind of form in the evolution of plant by obtaining or losing introns. Chromosomal location and duplication analysis revealed that segment and tandem duplication maybe the reasons of the expension of the GRAS family in cotton. Gene expression analysis confirmed the expression level of GRAS members were up-regulated under different abiotic stresses, suggesting that their possible roles in response to stresses. What's more, higher expression level in root, stem, leaf and pistil also indicated these genes may have effect on the development and breeding of cotton. Conclusions: This study firstly shows the comprehensive analysis of GRAS members in G. hirsutum. Our results provide important information about GRAS family and a framework for stress-resistant breeding in G. hirsutum.