Fungal effectors, the double edge sword of phytopathogens

Abstract

Phyto-pathogenic fungi can cause huge damage to crop production. During millions of years of coexistence, fungi have evolved diverse life-style to obtain nutrients from the host and to colonize upon them. They deploy various proteinaceous as well as non-proteinaceous secreted molecules commonly referred as efectors to sabotage host machinery during the infection process. The efectors are important virulence determinants of pathogenic fungi and play important role in successful pathogenesis, predominantly by avoiding host-surveillance system. However, besides being important for pathogenesis, the fungal efectors end-up being recognized by the resistant cultivars of the host, which mount a strong immune response to ward-of pathogens. Various recent studies involving diferent pathosystem have revealed the virulence/avirulence functions of fungal efectors and their involvement in governing the outcome of host–pathogen interactions. However, the efectors and their cognate resistance gene in the host remain elusive for several economically important fungal pathogens. In this review, using examples from some of the biotrophic, hemi-biotrophic and necrotrophic pathogens, we elaborate the double-edged functions of fungal efectors. We emphasize that knowledge of efector functions can be helpful in efective management of fungal diseases in crop plants.