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Web blight/wet root rot caused by Rhizoctonia solaniis 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 virensand R. solaniinteractions. 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. solaniand biocontrol agent T. virensusing conventional PCR and qPCR analyses. R. solaniinoculation 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. virensalone 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. virenssuppressed the development of disease in the presence of R. solaniin both susceptible and resistant varieties with more pronounced effect in resistant variety. Thus, the application of biocontrol agent T. virensupregulated the expression of defense-related genes and reduced disease development.

A specific and sensitive conventional and real-time PCR assays were developed for the detection and quantification of Rhizoctonia solanipopulations infecting pulses. Five different sets of R. solanispecific molecular primers ARSF1&R1, ARSF2&R2 and ARSF3&R3, ARSF4&R4 and ARSF5&R5 were designed from the internal transcribed spacer sequences of R. solaniisolates associated with pulse crops representing 7 anastomosis groups (AG1, AG2-2, AG2-2LP, AG2-3, AG3, AG4 and AG5). The designed primers yielded variable amplicons ranging from 174 to 563 bp specific to R. solanipopulations. The markers proved to be highly sensitive to R. solaniand were able to detect the pathogen from both mycelium and infected mung bean plants at various concentrations of genomic DNA ranging from 0.025 to 1.0 ng using conventional PCR. The markers were also found suitable for real-time PCR assay with enhanced sensitivity up to 1.24 pg genomic DNA. The efficacy of markers for early detection of R. solaniinfection in mung bean plants was also tested and the marker ARSF4&R4 was the most sensitive in detecting the pathogen at 24 h after artificial inoculation under field and at 6 h after artificial inoculation under in vitroconditions. The radioactive and fluorescein amidite labelled probes for markers ARSF4&R4 and ARSF5&R5 were designed and tested for cross-reactivity and sensitivity by Southern blotting and real-time PCR analyses, respectively. Both probes proved to be highly sensitive and specific only to R. solani.Both quantitative PCR and probe-based diagnostics have been developed for R. solanidetection in pulses.