Cell-wall-degrading enzymes produced in vitro and in vivo byRhizoctonia solani, the causative fungus of peanut sheath blight

Abstract

Rhizoctonia solani causes the disease peanut sheath blight, involving symptoms of maceration and necrosis of infected tissue, mainly caused by cell-wall-degrading enzymes (CWDEs). This study investigated the production of CWDEs including polygalacturonase (PG), polymethyl-galacturonase (PMG), cellulase (Cx) and β-glucosidase by R. solani in vitro (in liquid culture) and in vivo (in peanut plants). Significant PG, PMG, Cx and β-glucosidase activities were detected in infected tissues including stalk and leaves of Baisha and Silihong peanut cultivars. Extracts of healthy tissue showed little or no such activities. In shaken liquid cultures of R. solani in medium containing pectin or pectin plus carboxymethyl cellulose (CMC) as the carbon source(s), PG and PMG were notably active. Significant Cx activity was detected in cultures with CMC or pectin plus CMC as the carbon source(s). However, only a very low level of β-glucosidase activity was observed in cultures with any of the tested carbon sources. An increase of pH was recorded in decayed peanut tissues and liquid culture filtrates; the filtrate pH and fungal growth positively correlated. The fungal growth and/or pH were important factors for the production of PG, PMG and Cx in culture with pectin plus CMC as the carbon source. A single active PG isozyme with isoelectric point around 9.2 was detected in culture filtrates and in infected peanut tissues by the method of isoelectric focusing electrophoresis. The crude enzymes extracted from liquid culture of R. solani induced decay of healthy peanut leaves.

Strategies to Manage Rice Sheath Blight: Lessons from Interactions between Rice and Rhizoctonia solani

“…CAZymes mediate the degradation of cellulose, hemicellulose and pectin in host cell walls and break down the physical barrier of plant immune system, and thus enhancing pathogen virulence (Zheng et al 2013 ; Xia et al 2017 ). CWDEs in R. solani are categorized into seven major families including PG, endo-β- 1,4-glucanase, polymethylgalacturonase, pectin methylesterase, filter paper enzyme, polymethylgalacturonase trans-eliminas and pectin methyltrans-eliminase (Silva et al 2018 ; Xue et al 2018 ; Rathinam et al 2020 ). As a group of hydrolytic enzymes, PGs act on polygalacturonic acid, a key component of plant cell wall, by cleaving the α-(1,4)-glycosidic bonds, and thus causing hydrolysis of pectate.…”

Identity and prevalence of wheat damping-off fungal pathogens in different fields of Basrah and Maysan provinces

“…The effect of pathogens on the seedlings may be due to its ability to produce a group of enzymes that cause the fall of these seedlings. For example, R. solani produces polygalactoronase (PG), polymethyl-galactoronase (PMG), B-glucosidase and cellulas (Xue et al 2018),…”

Mycoparasitic Activity of Indigenous Trichoderma virens Strains Against Mungbean Soil Borne Pathogen Rhizoctonia solani: Hyperparasite and Hydrolytic Enzyme Production

“…This present study showed the complex mycoparasitism process of T. virens against R. solani. R solani has a unique character because besides having cell wall which contains chitin, it also produces cell wall-degrading enzymes including polygalacturonase (Cattelan, Hartel, & Fuhrmann, 1999), polymethyl-galacturonase (PMG), cellulase (Cx) and β-glucosidase which are potential to inhibit the growth of its antagonist such as Trichoderma (Xue, Zhou, Li, Xiao, & Fu, 2018). On the other hand, T. virens was one of the potential Trichoderma species which is very efficient in degrading cell walls of cellulases (Strakowska, Błaszczyk, & Chełkowski, 2014).…”