Natural variation in Zm FBL41 confers banded leaf and sheath blight resistance in maize

Rhizoctonia solani is a widely distributed phytopathogen that causes banded leaf and sheath blight in maize and sheath blight in rice. Here, we identified an F-box protein (ZmFBL41) that confers resistance to banded leaf and sheath blight through a genome-wide association study in maize. Rice overexpressing ZmFBL41 showed elevated susceptibility to R. solani. Two amino acid substitutions in this allele prevent its interaction with ZmCAD, which encodes the final enzyme in the monolignol biosynthetic pathway, resulting in the inhibition of ZmCAD degradation and, consequently, the accumulation of lignin and restriction of lesion expansion. Knocking out the ZmCAD-homologous gene OsCAD8B in rice enhanced susceptibility to R. solani. The results reveal a susceptibility mechanism in which R. solani targets the host proteasome to modify the secondary metabolism of the plant cell wall for its invasion. More importantly, it provides an opportunity to generate R. solani–resistant varieties of different plant species. Natural variation of the F-box protein ZmFBL41 in maize confers resistance to Rhizoctonia solani, the causal fungus for banded leaf and sheath blight in maize, through decreased interaction of ZmFBL41 with the cinnamyl alcohol dehydrogenase ZmCAD.