Changes in defense-related antioxidative enzymes amongst the resistant and susceptible soybean genotypes under whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae) stress

Soybean is one of the major pulse crops being cultivated in India. The production and productivity of soybean are greatly affected due to whitefly, Bemisia tabaci (Gennadius) feeding associated direct damage and indirectly due to yellow mosaic virus transmission. In the present study, activities of antioxidative enzymes viz. superoxide dismutase (SOD), peroxidase (POD) and polyphenol oxidase (PPO) were estimated spectrophotometrically from the leaf samples collected at two-time intervals (30 and 50 days after sowing) from the whitefly-infested and uninfested plants of eight soybean genotypes. Antioxidative enzyme activities (SOD, POD and PPO) were increased with B. tabaci infestation in all genotypes, with significant variation was recorded among the genotypes at both the sampling intervals. In general, SOD, POD and PPO activities were high in moderately resistant genotypes in whitefly-infested conditions and were negatively correlated with the whitefly population (nymphs and adults), suggesting that the increased activities might have been involved in providing defence against B. tabaci damage. The possible potential mechanisms involving higher antioxidative enzyme activities dealing the insect damage and offering resistance are also discussed.