Genome-wide identification of the ABA receptor PYL gene family and expression analysis in Prunus avium L.

The Pyrabactin resistance 1-like proteins (PYR/PYL/RCAR) are components of the ABA signaling pathway, playing a key role in how plants respond to abiotic stresses. Although PYL genes have been identified in a variety of plants, the evolution and structural characteristics of these genes in sweet cherry (Prunus avium L.) trees are largely unknown. In this study, 11 PaPYL genes were identified at genome-wide level in sweet cherry and were mapped to six chromosomes. According to the phylogenetic analysis, this gene family consisted of four subgroups; genes in the same subgroup had similar conserved motifs and the same number of exons, as revealed by analyzing gene structure. The intra-species collinearity analysis did not find any tandem duplication events in this gene family, and thus fragment duplication may be the primary reason for the generation of some PaPYL genes. Additionally, the inter-species collinearity analysis uncovered a potential evolutionary relationship between them. The expression analysis indicated that some PaPYL genes are specifically expressed in tissues, suggesting they may have unique functions. We also explored the expression of this gene family under different abiotic stress treatments (cold, salinity, drought). The qRT-PCR results showed that the expression levels of most genes were up-regulated under abiotic stress treatments, consistent with the results for their analyzed promoter cis-acting elements. This study provides a basis for further elucidating the function and expression patterning of the PYL gene family in sweet cherry, and helps to further analyze its regulatory mechanism under various abiotic stress factors.