Genome-wide characterization and expression analysis of PP2CA family members in response to ABA and osmotic stress in Gossypium.

Clade A type 2C protein phosphatases (PP2CAs), as central regulators of abscisic acid (ABA) signaling, negative control growth, development and responses to multiple stresses in plants. PP2CA gene families have been characterized at genome-wide levels in several diploid plants like Arabidopsis and rice. However, the information about genome organization, phylogenesis and putative functions of PP2CAs in Gossypium is lacking. Here, PP2CA family members were comprehensively analyzed in four Gossypium species including the diploid progenitor Gossypium arboreum, G. raimondii and the tetraploid G. hirsutum and G. barbadense, and 14, 13, 27, and 23 PP2CA genes were identified in the genomic sequences of these plants, respectively. Analysis results showed that most Gossypium PP2CAs were highly conserved in chromosomal locations, structures, and phylogeny among the four cotton species. Segmental duplication might play important roles in the formation of the PP2CAs, and most PP2CAs may be under purifying selection in Gossypium during evolution. The majority of the PP2CAs were expressed specifically in diverse tissues, and highly expressed in flowers in G. hirsutum. The GhPP2CAs displayed diverse expression patterns in responding to ABA and osmotic stress. Yeast-two hybrid assays revealed that many GhPP2CAs were capable of interaction with the cotton ABA receptors pyrabactin resistance1/PYR1-like/regulatory components of ABA receptors (PYR1/PYL/RCAR) GhPYL2-2D (Gh_D08G2587), GhPYL6-2A (Gh_A06G1418), and GhPYL9-2A (Gh_A11G0870) in the presence and/or absence of ABA. These results gave a comprehensive view of the Gossypium PP2CAs and are valuable for further studying the functions of PP2CAs in Gossypium.