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ThesisItem Open Access Enzymatic and Phytochemical Response to Spot Blotch (Bipolaris sorokiniana) Disease in Wheat(University of Agricultural Science, Dharwad, 2016-06) Mali, Komal V.; Mirajkar, Kiran K.Wheat is the important cereal crop in the world and second most important food crop of the country that contributes nearly one third of the total food grain production. Spot blotch is serious disease of wheat in warmer and humid regions of the world caused by Bipolaris sorokiniana infection. This work was conducted to evaluate the possible roles of antioxidative enzyme superoxide dismutase, catalase, glutathione reductase, phytochemical precursor enzyme phenylalanine ammonia lyase (PAL) and the pathogenesis-related proteins (PR-proteins) peroxidase (POX), total phenol content, lignin content and chlorophyll content in the resistant (NIDW295, PDW314) and susceptible (Bijaga yellow, A-9-301) durum wheat genotype in response to Bipolaris sorokiniana. 30 day after sowing inoculation was done and parameters were analysed in sample collected from uninoculated (control) and 48 hr after inoculation. Fungal inoculation induced significantly higher level of antioxidative enzyme superoxide dismutase (52.3 %), catalase (24.89 %), peroxidase (95.5 %), glutathione reductase (93.4 %) activity in resistant genotype (NIDW 295, PDW314) than susceptible genotype (Bijaga Yellow and A-9-301). Fungal inoculation induced significantly higher level of high PAL and peroxidase activity in NIDW295 and PDW314 than Bijaga Yellow and A-9-301. The total phenol and lignin content were significantly higher in resistant genotype but susceptible showed least increase. Increase in PAL and POX activity could be a determining factor for high phenolic production, lignin content and antifungal role by cell wall strengthening to enhance resistance against pathogen. Percent decrease in total chlorophyll content was higher in susceptible (Bijaga Yellow, A-9-301) than (NIDW295, PDW314). Overall study revealed that the higher amount of total phenols, lignin, antioxidant enzyme activity, phytochemical precursor enzyme PAL and chlorophyll content play an important role in defense mechanism of plants against wheat spot blotch infection in case of resistant varieties can be used as novel tool that can determined as biochemical marker for selection of resistant line against spot blotch.ThesisItem Open Access Enzymatic and Metabolic Studies of Salinity Stress Response in Rice (Oryza sativa L.)(University of Agricultural Science, Dharwad, 2016-06) Shashikumara R.; Mirajkar, Kiran K.A pot experiment was conducted at Main Agriculture Research Station, University of Agricultural Sciences, Dharwad during 2015 - 2016. The experiment was conducted in factorial CRD with three replications. Salt stress can lead to increase in the generation of reactive oxygen species (ROS) such as superoxide, hydrogen peroxide, hydroxyl radical and oxygen and plants possess complex antioxidative defense system comprising of non-enzymatic and enzymatic components to scavenge ROS. The current work aims to study the defense mechanism of rice genotypes (CSR 23 and BPT 5204) to salinity and the activity of the defensive enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), nitrogen assimilatory enzymes such as nitrate reductase and nitrite reductase in both leaves and roots, the amounts of total phenol, reducing sugar and chlorophyll content in leaves were analyzed in different levels of salinity (0, 8, 12 and 16 dSm-1). Salinity stress increased the activity of catalase, glutathione reductase and superoxide dismutase and total phenol content in both the genotypes, but the level of increases was high in CSR 23 compare to BPT 5204. Nitrogen assimilatory enzymes such as nitrate and nitrite reductase were very sensitive to salt stress and both the genotypes showed decreased activity under salinity. A decrease in reducing sugar content in both the genotypes i.e. percentage decreases was high in BPT 5204 compare to CSR 23 and photosynthetic pigments such as chlorophyll ‘a’, chlorophyll ‘b’ and total chlorophyll was observed in the leaves of rice genotypes under salinity stress. Photosynthetic pigments high in control and decreases in salinity stress. The improved performance of salt tolerant genotype (CSR 23) was associated with more efficient antioxidant system response under conditions of stress compare to salt sensitive genotype (BPT 5204).ThesisItem Open Access Biochemical Characterization in Cotton in Response to Incidence of Sucking Pest(University of Agricultural Science, Dharwad, 2016-06) Divya T.C.; Vamadevaiah, H.M.The field experiment was conducted at ARS Dharwad farm during kharif 2015-16 to study the level of biochemical metabolites namely total sugars, reducing sugars, non-reducing sugars, total phenols, condensed tannin , gossypol, available potassium, and the activity of the defensive enzymes such as nitrate reductase, peroxidase, lipoxygenase and also differential gene cationic peroxidase 3 , lipoxygenase 1 expression in resistant CPD14-1 and susceptible CPD14-2 genotypes in response to sucking pest infestation at 45, 85, 125 days after sowing. The results indicated that insect infestation increased the antioxidant enzyme activities viz., nitrate reductase, peroxidase, lipoxygenase activity and total sugars, phenols, tannin, gossypol and available potassium in resistant genotype than susceptable genotype at three different days interval. A decrease in plant height, boll number and reducing sugar was observed in the insect damage leaves compared with the control. Aphid population was also significantly higher in susceptible CPD14-2 genotype than resistant CPD14-1 genotype. The relative expression of cationic peroxidase 3 and lipoxygenase 1 gene was upregulated in CPD14-1 genotype than in CPD14-2 genotype in insect damage compared to control.
