Genome wide characterization revealed MnMLO2 and MnMLO6A as candidate genes involved in powdery mildew susceptibility in mulberry

Mulberry is a fast growing economically important tree for sericulture industry and contains compounds for preventing and treating several diseases and ailments. The quality and quantity of mulberry leaf available to produce silk fibre and for medicinal purpose is greatly affected by number of foliar diseases, out of which powdery mildew is the major one. Imparting genetic resistance becomes an important approach in disease management in mulberry as spraying of fungicides has harmful effects on silkworm growth and development. Deployment of non-functional susceptible genes such as Mildew resistance Locus O (MLO) against powdery mildew in few crops stimulated to identify and characterize MLO genes in mulberry. In this study, genome wide analysis identified 16 MLO genes in Morus notabilis. Phylogenetic analysis found that MnMLO2, MnMLO6A, MnMLO6B, MnMLO12A and MnMLO12B clustered with functionally characterized MLOs associated with powdery mildew susceptibility in dicot species. Gene expression analysis indicated increased transcript abundance of MnMLO2, MnMLO6A, and MnMLO12A in response to powdery mildew infection. Further, conserved motifs exclusive to functionally characterized MLOs were identified in MnMLO1C, MnMLO2 and MnMLO6A proteins. Combined analysis of the phylogenetic relationship, conserved motif analysis and gene expression in response to infection identified MnMLO2 and MnMLO6A as potential candidate genes involved in powdery mildew susceptibility in mulberry. Identification and deployment of natural and induced mutations in the candidate genes can be useful for mulberry breeding programs to develop powdery mildew resistant varieties.