Identification and functional inference on the MLO-family in viridiplantae

Powdery mildew (PM) is a widespread plant disease of temperate climates caused by ascomycete fungi of the order Erysiphales. PM is an important agricultural issue since it can cause significant economic losses. Specific members of the MLO gene family act as susceptibility factors towards the PM disease. A step towards the stability of crop productions would be thus the characterization of MLO genes at the genomic level. We carried out a genome-wide characterization of the MLO gene family in twenty-three plant and two algal genomes providing manual curated MLO protein catalogues. In total,180 novel proteins containing the MLO domain were identified. Evolutionary history and phylogenetic relationships were studied through maximum likelihood analysis. This highlighted eight different clades,including a new monocot-specific clade (VIII) identified for the first time. In addition,15 and 67 putative PM susceptibility genes,clustering in clade IV and V,respectively,were identified. Results of this work may help to address further biological questions concerning MLOs involved in PM susceptibility. In follow-up studies,it could be investigated whether the silencing or loss-of-function mutations in one or more of these candidate genes may lead to PM resistance.