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Subject: Agricultural Biochemistry × End date: 2016 × Start date: 2014 ×
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    ThesisItemOpen Access
    Biochemical Investigation of Biotic Stress Response of Mango (Mangifera indica L.) to Powdery Mildew Disease
    (University of Agricultural Science, Dharwad, 2016-07) Hipparagi, Laxman; Olekar, Nagaratna S.
    Plants respond to various biotic and abiotic stresses through the production of large amounts of reactive oxygen species (ROS). The research work aimed to study the defense mechanism of locally grown mango (Mangifera indica L.) varieties (Neelum and Totapuri) and hybrids (Neelgoa and Mallika) against mango powdery mildew. This study was attempted to evaluate the role of phytochemicals (total phenol, reducing sugar and antioxidant enzymes) as defence response against powdery mildew infection in mango genotypes. A number of biochemical compounds including sugars, phenolic compounds, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), polyphenol oxidase (PPO) and ascorbate oxidase (AO) have been implicated to play a crucial role in the tolerance/resistance of different mango cultivars to powdery mildew infection. After powdery mildew infection, there was increased antioxidant enzyme activity in all infected leaves compared to healthy leaves. Among all genotypes Mallika showed higher activity for all the enzymes mentioned above except in case of glutathione reductase activity and lower antioxidant activity of all enzymes were observed in Neelum except in case of glutathione reductase where in lower activity was observed in Totapuri. The total phenols were observed more in Neelum compared to other genotypes and lower phenols were observed in Neelgoa. Reducing sugar decreased because of powdery mildew infection and higher sugar content was observed in Neelum where as lower content was recorded in Mallika. As powdery mildew disease infects mainly to leaf portion because of this chlorophyll content was reduced. The higher total chlorophyll content was observed in Mallika and lower content was recorded in Neelum due to disease infection. This study underlines the significance of enzymatic ROS scavenging system in disease resistance/susceptibility.