Influence of Temperature on the Pathogenesis and Gene Expression of Rhizoctonia solani Causing Web Blight/Wet Root Rot Disease in Mungbean

Mungbean [Vigna radiata (L.) Wilzeck] is one of the most important pulse crops and grown in almost all parts of the India. Web blight/wet root rot disease of mungbean is caused by Rhizoctonia solani Kuhn. Crop environmental factors plays a vital role in the development of web blight disease caused by R. solani. An understanding of the role of environmental factors on the infection and survival of the pathogen is necessary to develop disease management practices.

The effect of different temperatures (4°C, 20°C, 25°C, 30°C and 35°C) on mycelial growth of seven different R. solani isolates belonging to different anastomosis group were evaluated under in vitro conditions. Effect of different temperatures on the development of root rot/web blight disease of mungbean was also evaluated under phytotron conditions at various temperatures with constant relative humidity (85%) and illumination (alternate dark and light period of 12 h). Effect of temperatures on the expression of selected pathogenicity related genes was evaluated through real time PCR.

Maximum radial growth in R. solani isolates was observed at 25 and 30°C after 48 hrs of incubation. Maximum disease incidence was observed with R. solani isolate RUPU-18 (73.11%) followed by R-17 (68.75%), RDLM-1 (63.45%) at 25°C on mungbean genotype Pusa Vishal. Expression of genes like ABC transporter was observed only at 35°C, while other genes like 1, 3 glucan hydrolase expressed maximum at 25°C after 24, 48 and 72 hrs post inoculation. Present study suggested that the expression of pathogenicity related genes in mungbean-R. solani system is dependent on the temperature and time interval post pathogen inoculation.