Protein kinases (PKs) are involved in plant growth and stress responses, and constitute one of the largest superfamilies due to numerous gene duplications. However, limited PKs have been functionally described in pecan, an economically important nut tree. Here, the comprehensive identification, annotation and classification of the entire pecan kinome was reported. A total of 967 PK genes were identified from pecan genome, and further classified into 20 different groups and 121 subfamilies using the kinase domain sequences, which were verified by the phylogenetic analysis. The receptor-like kinase (RLK) group contained 565 members, which constituted the largest group. Gene duplication contributed to the expansion of pecan kinome, 169 duplication events including 285 PK genes were found, and Ka/Ks ratio revealed they experienced strong negative selection. GO functional analysis indicated majority PKs involved in molecular functions and biological processes. The RNA-Seq data of PK genes in pecan were further analyzed at subfamily level, and different PK subfamilies performed various expression patterns across different conditions or treatments, suggesting PK genes in pecan involved in multiple biological functions and stress responses. Taken together, this study provided insight into the expansion, evolution and function of pecan PKs. Our findings regarding expansion, expression and co-expression analyses could lay a good foundation for future research to understand the roles of pecan PKs, and find the key candidate genes more efficiently.
Overall design: Plant leaf samples were harvested at 0, 3, 6, 9, 12, and 15 days after drought treatment.
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