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

• Published in: PeerJ (San Francisco, CA) Vol. 6; p. e5580
• Main Authors: Xue, Cai Yun, Zhou, Ru Jun, Li, Yuan Jie, Xiao, Di, Fu, Jun Fan
• Format: Journal Article
• Language: English
• Published: United States PeerJ, Inc 05.09.2018; PeerJ Inc
• Subjects: Agricultural Science; Carbon sources; Carboxymethylcellulose; Cell culture; Cell-wall-degrading enzymes; Cellulase; Cellulose; Cloning; Enzymes; Fungi; Genes; IEF; Infections; Isoelectric focusing; Leaves; Liquid culture; Microbiology; Mycology; Pathogens; Peanut; Peanut sheath blight disease; Pectin; pH effects; Plant diseases; Plant pathology; Polygalacturonase; Rhizoctonia solani; Sheath blight; China; Peanut; Rhizoctonia solani; IEF; Peanut sheath blight disease; Cell-wall-degrading enzymes
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.5580

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 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 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 induced decay of healthy peanut leaves.