A Fungal Glycoside Hydrolase From Colletotrichum asianum Mini-Chromosomes Targets Host Chitinase to Suppress Plant Immunity.

Colletotrichum asianum, the cause of mango anthracnose, is a major threat to mango production worldwide. However, the mechanisms underlying plant invasion by C. asianum are poorly understood. Mini-chromosomes are increasingly recognised as indispensable components in the virulence of plant-pathogenic fungi. Here, we identify CaMutA, a secreted glycoside hydrolase 71 effector encoded on a mini-chromosome, as a critical pathogenicity factor that suppresses plant immune responses and is essential for infection by C. asianum. CaMutA directly interacts with the mango chitinase MiChi1. When heterologously expressed in Arabidopsis thaliana, MiChi1 confers enhanced resistance against multiple pathogens, suggesting its role in plant defence, a process that CaMutA subverts. Together, our findings uncover that a mini-chromosome-encoded effector can subvert plant immunity by directing the ubiquitin-mediated degradation of conserved defence-related chitinases. This study thus identifies promising targets for controlling mango anthracnose.