Expression of defense-related genes in mung bean varieties in response to Trichoderma virens alone and in the presence of Rhizoctonia solani infection

Abstract

Web blight/wet root rot caused by Rhizoctonia solani is one of the major constraints for mung bean (Vigna radiata) production. Growing of resistant varieties and use of biocontrol agents are the feasible options available to manage the disease. The present study was conducted to determine the variation in the expression of various defense-related genes in susceptible and resistant mung bean varieties in response to biocontrol agent Trichoderma virens and R. solani interactions. The primers were designed using sequences of defense-related genes, namely PR 10, epoxide hydrolase (EH), catalase and calmodulin available in NCBI database and evaluated against cDNA obtained from both susceptible and resistant mung bean plants at 1-4 days post-inoculation (dpi) with the test pathogen R. solani and biocontrol agent T. virens using conventional PCR and qPCR analyses. R. solani inoculation upregulated the mean expression of PR 10 and calmodulin in susceptible and resistant varieties, respectively, whereas downregulated in the rest of the treatments. Quantitative PCR analysis showed that except catalase in the susceptible variety, which is downregulated, the expression of PR 10, EH, catalase and calmodulin was upregulated in both resistant and susceptible varieties in response to T. virens alone and in the presence of R. solani. In general, the expression of PR 10 and calmodulin was highest at 1 dpi whereas EH and catalase expression were maximum at 4 dpi. The application of T. virens suppressed the development of disease in the presence of R. solani in both susceptible and resistant varieties with more pronounced effect in resistant variety. Thus, the application of biocontrol agent T. virens upregulated the expression of defense-related genes and reduced disease development.

Keywords: Induced systemic resistance (ISR); Mung bean–T. virens–R. solani interaction; Real-time PCR; Systemic acquired resistance (SAR).

Fig. 1

Expression of PR10 gene in susceptible mung bean variety Ratna at different days post-inoculation with Rhizoctonia solani, Trichoderma virens, T. virens + R. solani and un-inoculated (control)

Fig. 2

Expression of PR10 gene in resistant mung bean variety HUM 1 at different days post-inoculation with Rhizoctonia solani, Trichoderma virens, T. virens + R. solani and un-inoculated (control)

Fig. 3

Expression of epoxide hydrolase gene in susceptible mung bean variety Ratna at different days post-inoculation with Rhizoctonia solani, Trichoderma virens, T. virens + R. solani and un-inoculated (control)

Fig. 4

Expression of epoxide hydrolase gene in resistant mung bean variety HUM 1 at different days post-inoculation with Rhizoctonia solani, Trichoderma virens, T. virens + R. solani and un-inoculated (control)

Fig. 5

Expression of catalase gene-susceptible mung bean variety Ratna at different days post-inoculation with Rhizoctonia solani, Trichoderma virens, T. virens + R. solani and un-inoculated (control)

Fig. 6

Expression of catalase gene in resistant mung bean variety HUM 1 at different days post-inoculation with Rhizoctonia solani, Trichoderma virens, T. virens + R. solani and un-inoculated (control)

Fig. 7

Expression of calmodulin gene in susceptible mung bean variety Ratna at different days post-inoculation with Rhizoctonia solani, Trichoderma virens, T. virens + R. solani and un-inoculated (control)

Fig. 8

Expression of calmodulin gene in resistant mung bean variety HUM 1 at different days post-inoculation with Rhizoctonia solani, Trichoderma virens, T. virens + R. solani and un-inoculated (control)