Arabidopsis nonhost resistance gene PENETRATION 2 is involved in disruption of cushion formation by Rhizoctonia solani during early infection process

Abstract

Rice sheath blight, a major devastating disease caused by Rhizoctonia solani, poses huge threat to global rice production. Despite being the most hostile necrotrophic fungus with a wide host range, the mechanism involved in R. solani pathobiology is poorly understood. The evolutionarily developed nonhost resistance (NHR) provides broad-spectrum disease resistance to food crops. According to previous reports, Arabidopsis PEN1, PEN2 and PEN3 act as key components of cell wall-based pre-haustorial defenses against non-adapted pathogens. However, the involvement of these PEN genes in NHR against R. solani has remained unexplored till date. Therefore, the objective of this work is to study the efficacy of Arabidopsis PEN genes in NHR against R. solani. For this, hyphal colonization and penetration structures were monitored in Arabidopsis wild type Columbia-0 (Col-0) and mutants- pen1, pen2–3 and pen3–1. Comparatively, R. solani colonization on the leaves of Arabidopsis wild types was less than that on the rice leaf surface. Also, among the pen mutants studied, pen2–3 allowed maximum penetration and colonization by R. solani during early hours of infection as evidenced by both microscopic and macroscopic observations. Advanced lesion area, reduced chlorophyll content and increased fungal biomass accumulation also corroborated with the disease severity in pen2–3. However, R. solani resistance was restored in complemented PEN2-GFP comparable to Col-0. Altogether, our results demonstrate major involvement of PEN2 during pre-penetration, and its contribution to NHR against R. solani for enhanced disease resistance.