Genome-wide identification and expression analysis of the GhIQD gene family in upland cotton (Gossypium hirsutum L.)

Abstract

Background: Calmodulin (CaM) is one of the most important Ca 2+ signaling receptors because it regulates diverse physiological and biochemical reactions in plants. CaM functions by interacting with CaM-binding proteins (CaMBPs) to modulate Ca 2+ signaling. IQ domain (IQD) proteins are plant-specific CaMBPs that bind to CaM by its specific CaM binding sites. Result: In this study, we firstly identified 102 GhIQD genes in the Gossypium hirsutum L. genome. The GhIQD gene family was classified into seven clusters (Ia, Ib, Ic, II, IIIa, IIIb and IV), and we then mapped the GhIQD genes to the 26 chromosomes. Moreover, we found that 100 of the 102 GhIQD genes resulted from segmental duplication events, indicating that segmental duplication is the main force driving GhIQD gene expansion. Gene expression pattern analysis showed that a total of 89 GhIQD genes are expressed in the elongation stage and second cell wall biosynthesis stage of the fiber cells, suggesting that GhIQD genes may contribute to fiber cell development in cotton. In addition, we found that 20 randomly-selected GhIQD genes were highly expressed in different tissues. Exogenous application of MeJA significantly enhanced the expression levels of GhIQD genes. Conclusion: Our study shows that GhIQD genes are involved in fiber cell development in cotton and are also widely induced by MeJA, which provides a basis to systematically characterize the evolution and biological functions of GhIQD genes, as well as clues to breed better cotton varieties in the future.