Plants being sessile are under constant threat of multiple abiotic and biotic stresses within its natural habitat. A combined stress involving an abiotic and a biotic factor reportedly increases susceptibility of the plants to pathogens. The emerging threat, collar rot disease of chickpea (caused by Sclerotium rolfsii Sacc.) is reported to be influenced by soil moisture condition (SMC). Hence, we studied the influence of differential SMC viz. upper optimum (100%), optimum (80%), lower optimum (60%), and limiting (40%) soil moisture conditions on colonization and collar rot development over the course of infection in two chickpea cultivars, Annigeri (susceptible to collar rot) and ICCV 05530 (moderately resistant to collar rot). Disease incidence was found to be directly proportional to increase in soil moisture (R2 = 0.794). Maximum incidence was observed at 80% SMC, followed by 100 and 60% SMC. Expression of genes (qPCR analysis) associated with host cell wall binding (lectin) and degradation viz. endopolygalacturonase-2, endoglucosidase, and cellobiohydrolase during collar rot development in chickpea were relatively less at limiting soil moisture condition (40%) as compared to optimum soil moisture condition (80%). As compared to individual stress, the expression of defense response genes in chickpea seedlings were highly up-regulated in seedlings challenged with combined stress. Our qPCR results indicated that the expression of defense-related genes in chickpea during interaction with S. rolfsii at low SMC was primarily responsible for delayed disease reaction. Involvement of moisture and biotic stress-related genes in combined stress showed a tailored defense mechanism.

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Chickpea (Cicer arietinum L.) is an important cool-season food legume grown extensively by the poor farmers throughout the Indian subcontinent. In India chickpea is being grown in 8.32 million hectare with production of 9.8 million tones and 925 -kg/ha productivity (Project coordinators report, 2014-15). The Dry root rot (DRR) of chickpea caused by necrotropic fungus Rhizoctonia bataticola. During the past few decades, modern techniques such as mutation breeding by radiation and chemical mutagens and genetic engineering methodology have been tried to develop resistant cultivars of many crop plants. The utilization of mutation breeding is a simple, less cost full and time saving method. Present investigation entitled "Radiation induced mutation for resistance against Rhizoctonia bataticola in chickpea (Cicer arietinum Linn.)" was aimed at identification of suitable mutant or a combination of mutants influencing resistance to dry root rot in chickpea. The experimental material was consisted of the population of three selected cultivars of chickpea (JG 63, JG 74, and JG 130) grown in randomized complete block design in the Seed Breeding Farm, Department of Plant Breeding and Genetics, College of Agriculture, Jabalpur (M.P) under AICRP on chickpea project during Rabi 2014-15. Dry seeds (10-12% moisture content) of these varieties were irradiated with different doses of gamma rays (150Gy, 200Gy and 400 GY). Another set of presoaked seeds in distilled water (12hrs.) were treated with ethyl methane sulphonate at different concentration (0.3, 0.4 and 0.5%) prepared for 6 hrs. A portion of seeds irradiated at 150 and 200 GY gammaray doses were also treated with 0.3% and 0.4% EMS independently for 6 hrs. present findings revealed that JG 63, JG 74, JG 130 showed significant reaction for mutagenic treatments i.e, 200Gy, 400Gy, 0.3% EMS, 0.4% EMS, 150Gy+0.3% EMS, 200Gy+0.3% EMS. Among 11 treatments, 7 have shown effect on biological traits of experimental genotypes i.e. change in seedling height, decrease in germination percentage and decrease in plant height as compared to control. K e y w o r d sRhizoctonia bataticola, Gammaray, EMS, Cicer arietinum L

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