Genome-Wide Identification and Characterization of the LRR-RLK Gene Family in Two Vernicia Species.

Leucine-rich repeat receptor-like kinases (LRR-RLKs) make up the largest group of RLKs in plants and play important roles in many key biological processes such as pathogen response and signal transduction. To date, most studies on LRR-RLKs have been conducted on model plants. Here, we identified 236 and 230 LRR-RLKs in two industrial oil-producing trees: Vernicia fordii and Vernicia montana, respectively. Sequence alignment analyses showed that the homology of the RLK domain (23.81%) was greater than that of the LRR domain (9.51%) among the Vf/VmLRR-RLKs. The conserved motif of the LRR domain in Vf/VmLRR-RLKs matched well the known plant LRR consensus sequence but differed at the third last amino acid (W or L). Phylogenetic analysis revealed that Vf/VmLRR-RLKs were grouped into 16 subclades. We characterized the expression profiles of Vf/VmLRR-RLKs in various tissue types including root, leaf, petal, and kernel. Further investigation revealed that Vf/VmLRR-RLK orthologous genes mainly showed similar expression patterns in response to tree wilt disease, except 4 pairs of Vf/VmLRR-RLKs that showed opposite expression trends. These results represent an extensive evaluation of LRR-RLKs in two industrial oil trees and will be useful for further functional studies on these proteins.