The RsRlpA Effector Is a Protease Inhibitor Promoting Rhizoctonia solani Virulence through Suppression of the Hypersensitive Response

Abstract

Rhizoctonia solani (Rs) is a soil-borne pathogen with a broad host range. This pathogen incites a wide range of disease symptoms. Knowledge regarding its infection process is fragmented, a typical feature for basidiomycetes. In this study, we aimed at identifying potential fungal effectors and their function. From a group of 11 predicted single gene effectors, a rare lipoprotein A (RsRlpA), from a strain attacking sugar beet was analyzed. The RsRlpA gene was highly induced upon early-stage infection of sugar beet seedlings, and heterologous expression in Cercospora beticola demonstrated involvement in virulence. It was also able to suppress the hypersensitive response (HR) induced by the Avr4/Cf4 complex in transgenic Nicotiana benthamiana plants and functioned as an active protease inhibitor able to suppress Reactive Oxygen Species (ROS) burst. This effector contains a double-psi beta-barrel (DPBB) fold domain, and a conserved serine at position 120 in the DPBB fold domain was found to be crucial for HR suppression. Overall, R. solani seems to be capable of inducing an initial biotrophic stage upon infection, suppressing basal immune responses, followed by a switch to necrotrophic growth. However, regulatory mechanisms between the different lifestyles are still unknown.

Keywords

basidiomycete; biotrophy; effector; cathepsin; hypersensitive response; papain inhibitor; protease; soil-borne pathogen; sugar beet

Published in

International Journal of Molecular Sciences
2020, volume: 21, number: 21, article number: 8070

SLU Authors

• Dölfors, Fredrik

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    

• Moschou, Panagiotis Nikolaou

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    
  • Foundation for Research and Technology - Hellas (FORTH)
  • University of Crete

• Dixelius, Christina

  • Department of Plant Biology, Swedish University of Agricultural Sciences
    

• Tzelepis, Georgios

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network

UKÄ Subject classification

Agricultural Science

Publication identifier

• DOI: https://doi.org/10.3390/ijms21218070

Permanent link to this page (URI)

https://res.slu.se/id/publ/108782