Genome-wide identification of the PYL gene family and expression of PYL genes under abiotic stresses in Chinese cabbage

The family of pyrabactin resistance 1 (PYR1)/PYR1-like (PYL) regulatory components of ABA receptors (RCAR) play a vital role in the initial step of ABA signaling. To understand the expression mode of PYL genes in response to various abiotic stresses in Chinese cabbage ( Brassica rapa ssp. pekinensis ), the members of BrPYL gene family were first identified with the relevant bioinformatics software. And then, the relative expressions of identified BrPYLs after heat, cold, drought, and salt treatments for 0, 24, 48, and 72 h were determined via real-time quantitative PCR. Here, we identified 24 PYLs in the B. rapa genome. Based on the phylogenetic analysis, these BrPYL genes were divided into three classes and distributed on ten chromosomes in Chinese cabbage. Most of BrPYL genes in the same group have similar gene structures and intron numbers. There were seven genes ( BrPYL 5, BrPYL8 , BrPYL22 , BrPYL3 , BrPYL18 , BrPYL11 , and BrPYL21 ) from Group A with two introns and one gene ( BrPYL19 ) from Group D with one intron. Analysis of conserved motifs suggested that every group contained motif 2 containing the Polyketide_cyc2 domain. Subsequently, the prediction of cis -acting elements indicated that BrPYL genes had 5 stress-related elements and 5 hormone-related elements, among which the number of MYC (dehydration reaction) was the highest, suggesting that BrPYL genes could respond to hormones and abiotic stresses. Expression patterns under four abiotic stresses showed that the expressions of BrPYL4 , BrPYL11 , BrPYL21 , and BrPYL23 responded to these stresses at different time points. To conclude, we identified the BrPYL genes and build the BrPYLs expression mode in response to various abiotic stresses. This study provides a theoretical basis for stress-resistance breeding of Chinese cabbage.