Genome comparison implies the role of Wsm2 in membrane trafficking and protein degradation.

(WSMV) causes streak mosaic disease in wheat ( L.) and has been an important constraint limiting wheat production in many regions around the world. is the only resistance gene discovered in wheat genome and has been located in a short genomic region of its chromosome 3B. However, the sequence nature and the biological function of remain unknown due to the difficulty of genetic manipulation in wheat. In this study, we tested WSMV infectivity among wheat and its two closely related grass species, rice () and . Based on the phenotypic result and previous genomic studies, we developed a novel bioinformatics pipeline for interpreting a potential biological function of and its ancestor locus in wheat. In the WSMV resistance tests, we found that rice has a WMSV resistance gene while does not, which allowed us to hypothesize the presence of a ortholog in rice. Our OrthoMCL analysis of protein coding genes on wheat chromosome 3B and its syntenic chromosomes in rice and discovered 4,035 OrthoMCL groups as preliminary candidates of orthologs. Given that is likely duplicated through an intrachromosomal illegitimate recombination and that is dominant, we inferred that this new WSMV-resistance gene acquired an activation domain, lost an inhibition domain, or gained high expression compared to its ancestor locus. Through comparison, we identified that 67, 16, and 10 out of 4,035 OrthoMCL orthologous groups contain a rice member with 25% shorter or longer in length, or 10 fold more expression, respectively, than those from wheat and Taken together, we predicted a total of 93 good candidates for a ancestor locus. All of these 93 candidates are not tightly linked with , indicative of the role of illegitimate recombination in the birth of . Further sequence analysis suggests that the protein products of may combat WSMV disease through a molecular mechanism involving protein degradation and/or membrane trafficking. The 93 putative ancestor loci discovered in this study could serve as good candidates for future genetic isolation of the true locus.