Evolutionary Dynamics of the Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) Subfamily in Angiosperms

摘要

Gene duplications are an important factor in plant evolution, and lineage-specific expanded () genes are of particular interest. Receptor-like kinases expanded massively in land plants, and leucine-rich repeat receptor-like kinases () constitute the largest receptor-like kinases family. Based on the phylogeny of 7,554 genes from 31 fully sequenced flowering plant genomes, the complex evolutionary dynamics of this family was characterized in depth. We studied the involvement of selection during the expansion of this family among angiosperms. subgroups harbor extremely contrasting rates of duplication, retention, or loss, and copies are predominantly found in subgroups involved in environmental interactions. Expansion rates also differ significantly depending on the time when rounds of expansion or loss occurred on the angiosperm phylogenetic tree. Finally, using a dN/dS-based test in a phylogenetic framework, we searched for selection footprints on and single-copy genes. Selective constraint appeared to be globally relaxed at genes, and codons under positive selection were detected in 50% of them. Moreover, the leucine-rich repeat domains, and specifically four amino acids in them, were found to be the main targets of positive selection. Here, we provide an extensive overview of the expansion and evolution of this very large gene family.