Arabidopsis PEN2, a promising gene in upraising penetration resistance against rice necrotrophic fungus Rhizoctonia solani

Rhizoctonia solani, a soilborne necrotroph, causes sheath blight in rice which poses a major threat to global rice production. Besides rice sheath blight, it has a wide host range of other economically important crops like soybean, sugarcane, maize etc. Despite being the most hostile fungus, the mechanism involved in the R. solani pathobiology is poorly understood. Non-host resistance (NHR) is an emerging concept that allows breeders to transfer traits to food crops that would impart a broad-spectrum disease resistance. Several NHR genes are known to function against different pathogens of which Arabidopsis PEN1, PEN2 and PEN3 have been reported to limit the entry of non-adapted powdery mildews and provide cell wall based defenses against different fungi. Till now, there has been no study regarding the involvement of these PEN genes against R. solani. In this study, we have screened pen1, pen2-3 and pen3-1 against R. solani to explore their contribution in penetration resistance. Among the three pen mutants studied, pen2-3 allowed maximum penetration during the early hours of infection. R. solani colonization was also observed in pen1 and pen3-1 but the effect was less drastic than pen2-3, suggesting the involvement of PEN2 in pre-invasive defense. To validate our hypothesis, we screened a complemented pen2 accession, PEN2-GFP, which showed restored penetration resistance comparable to Col-0. Altogether, our results demonstrate that PEN2 is involved in pre-penetration resistance, and contributes to NHR by enhanced disease resistance to R. solani.