Genome-wide identification of ABA receptor PYL family and expression analysis of PYLs in response to ABA and osmotic stress in Gossypium

Abscisic acid (ABA) receptor pyrabactin resistance1/PYR1-like/regulatory components of ABA receptor (PYR1/PYL/RCAR) (named PYLs for simplicity) are core regulators of ABA signaling, and have been well studied in Arabidopsis and rice. However, knowledge is limited about the PYL family regarding genome organization, gene structure, phylogenesis, gene expression and protein interaction with downstream targets in Gossypium. A comprehensive analysis of the Gossypium PYL family was carried out, and 21, 20, 40 and 39 PYL genes were identified in the genomes from the diploid progenitor G. arboretum, G. raimondii and the tetraploid G. hirsutum and G. barbadense, respectively. Characterization of the physical properties, chromosomal locations, structures and phylogeny of these family members revealed that Gossypium PYLs were quite conservative among the surveyed cotton species. Segmental duplication might be the main force promoting the expansion of PYLs, and the majority of the PYLs underwent evolution under purifying selection in Gossypium. Additionally, the expression profiles of GhPYL genes were specific in tissues. Transcriptions of many GhPYL genes were inhibited by ABA treatments and induced by osmotic stress. A number of GhPYLs can interact with GhABI1A or GhABID in the presence and/or absence of ABA by the yeast-two hybrid method in cotton.