Genome-wide identification and expression of abscisic acid receptor PYL gene family in oil palm

【Objective】In this research, the oil palm(Elaeis guineensis) abscisic acid receptor PYR/PYL/RCARs(PYL) gene family members were identified, and their expression characteristics during fruit development and abscisic acid(ABA) treatment were analyzed, which provided evidence for researching the mechanism of ABA signaling pathway in fruit maturation of oil palm.【Method】The amino acid sequences of Arabidopsis and rice PYL protein were query sequences, identified PYL gene family members from oil palm genome via BLASTp and conservative domain prediction analysis. The chromosomal location, gene structure, promoter cis-acting elements, protein physicochemical properties, conserved functional domains and evolutionary relationships were analyzed through bioinformatics softwares. The expression characteristics of PYL family gene in different, mesocarp at different stages and ABA treatment were analyzed by real-time fluorescence quantitative PCR.【Result】The results showed that 12 PLY(EgPYL1-EgPYL12) gene family members were identified form oil palm genome and were distributed on 8 chromosomes and 1 Scaffolds. The extrons numbers of EgPYL family members were between 1 and 3, the open reading frames(ORF) length were between 564 and 765 pb and encoded amino acid numbers were between 187 and 254. The molecular weights were between 20.95 and 28.33 kD, the isoelectric points were between 5.26 and 7.95, the instability indexes were between 32.67 and 52.87, the aliphatic indexes were between 73.87 and 87.60, the total hydrophilicity was between-0.68 and-0.17. Twelve PYL family protein contained PYR/PYL/RCAR functional domain and were divided into 3 groups based on phylogenetic relationships. Collinearity analysis showed that collinearity existed between EgPYL1 gene and EgPYL6 gene, EgPYL4 gene, EgPYL5 gene, EgPYL9 gene and EgPYL11 gene. A large number of plant hormone responses, stress responses and light responses elements were identified on promoters of EgPYLs gene. Expression analysis of different tissues showed that the EgPYLs gene expressed in roots, shoots, leaves, flowers and fruits, with great difference. During fruit maturation, the expressions of EgPYL7, EgPYL8 and EgPYL9 genes increased gradually and reached the peak at 23 weeks after anthesis. Eleven EgPYLs were induced by exogenous ABA treatment.【Conclusion】Most PYL gene family members are involved in responding to abscisic acid, among them EgPYL7, EgPYL8 and EgPYL9 genes might play important roles in regulating oil palm mesocarp development.