Arabidopsis L-type lectin receptor kinases: phylogeny, classification, and expression profiles

In plants, lectin receptor kinases are considered to play crucial roles during development and in the adaptive response to various stimuli. Arabidopsis lectin receptor kinases can be divided into three type-classes based on sequence similarity of their extracellular lectin motifs. The current study focuses on the legume-like lectin receptor kinases (LecRKs), which are regarded as ideal candidates for monitoring cell wall integrity and are possibly functional in adaptive responses. An inventory of the Arabidopsis LecRK gene family is presented here. It consists of 45 members including three that were recently identified; two encode N-terminal truncated variants one of which has two in tandem kinase domains. Phylogenetic trees derived from full-length amino acid sequence alignments were highly concordant to phylograms that were purely based on lectin motifs or kinase domains. The phylograms allowed reclassification of the LecRK genes and hence a new proposal for gene nomenclature was suggested. In addition, a comprehensive expression analysis was executed by exploring public repositories. This revealed that several LecRK genes are differentially expressed during plant growth and development. Moreover, multiple LecRKs appear to be induced upon treatment with elicitors and pathogen infection. Variation in gene expression was also analysed in seedlings of diverse Arabidopsis accessions. Taken together, this study provides a genome-wide overview of the LecRK gene family and an up-to-date classification using a novel and systematic gene nomenclature.