Genome-wide analysis and evolution of plant thaumatin-like proteins: a focus on the origin and diversification of osmotins.

Osmotin is an important multifunctional protein related to plant stress responses and is classified into the thaumatin-like protein (TLP) family. Using genome-wide and phylogenetic approaches, we investigated osmotin origin and diversification across plant TLP evolution. Genomic and protein in silico analysis tools were also accessed and considered for the study conclusions. Phylogenetic analysis including a total of 722 sequences from 32 Viridiplantae species allowed the identification of an osmotin group that includes all previously characterized osmotins. Based on the phylogenetic tree results, it is evident that the osmotin group emerged from spermatophytes. Phylogenetic separation and gene expansion could be accounted for by an exclusive motif composition and organization that emerged and was maintained following tandem and block duplications as well as natural selection. The TLP family conserved residues and structures that were also identified in the sequences of the osmotin group, thus suggesting their maintenance for defense responses. The gene expression of Arabidopsis and rice putative osmotins reinforces its roles during stress response.