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Evolutionary dynamics of the Leucine-Rich Repeats Receptor-Like Kinase (LRR-RLK) subfamily in angiosperms

Fischer I., Diévart A., Droc G., Dufayard J.F., Chantret N.. 2016. Plant Physiology, 170 (3) : p. 1595-1610.

DOI: 10.1104/pp.15.01470

Gene duplications are an important factor in plant evolution and lineage specific expanded (LSE) genes are of particular interest. Receptor-like kinases (RLK) expanded massively in land plants and Leucine-Rich Repeat (LRR)-RLKs constitute the largest RLK family. Based on the phylogeny of 7,554 LRR-RLK 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. LRR-RLK subgroups harbor extremely contrasted rates of duplication, retention or loss and LSE 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 LSE and single-copy LRR-RLK genes. Selective constraint appeared to be globally relaxed at LSE genes and codons under positive selection were detected in 50% of them. Moreover, the LRR 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.

Mots-clés : phylogénie; évolution; gène; séquence nucléotidique; génome

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