Peroxidative Responses of Leaves in Two Soybean Genotypes Injured by Twospotted Spider Mites (Acari: Tetranychidae)

Oxidative Responses of Resistant and Susceptible Cereal Leaves to Symptomatic and Nonsymptomatic Cereal Aphid (Hemiptera: Aphididae) Feeding

“…This Þnding indicates that damage symptom development on these two cereals may be related to D. noxia-elicited plant oxidative responses, because the nonsymptomatic R. padi did not elicit any signiÞcant increases of oxidative enzyme activities. The Þndings from the current study support a number of previous reports that have demonstrated that oxidative enzymes (e.g., peroxidase, catalase, and polyphenol oxidase) in plants play an important role in responding to biotic and abiotic stresses (Hildebrand et al 1986;Zhang and Kirkham 1994;Felton et al 1994aFelton et al . 1994b).…”

“…Excised leaf tissue was processed following the protocol described by Hildebrand et al (1986). Cold potassium phosphate buffer (0.1 M, pH 7.0) containing 1% (wt: vol) polyvinylpyrrolidone and 1% (vol:vol) Triton X-100 was added to a chilled (4ЊC) mortar and pestle containing the excised leaf sample.…”

“…Peroxidase activity was determined by monitoring the increase in absorbance at 470 nm for 2 min at room temperature using a modiÞed protocol described by Hildebrand et al (1986) and Hori et al (1997). The reaction was initiated by adding 200 l of 0.3% hy-drogen peroxide into a reaction mixture containing 300 l of 20 mM guaiacol, 250 l of 0.1 M potassium phosphate buffer (pH 6.0), 240 l of distilled water, and 10 l of cereal enzyme extract.…”

“…Although a considerable amount of work has been reported on herbivores with chewing mouthparts, only a few studies have examined plant oxidative responses to sapfeeding insects. Feeding of twospotted spider mites, Tetranychus urticae Koch, on soybean, Glycine max (L.) Merr., elicits peroxidative responses in soybean leaves (Hildebrand et al 1986), and resistance to T. urticae feeding and plant lipid peroxidation is strongly correlated in soybean genotypes. Both soybean resis-tance and lipid peroxidation were also correlated to carotenoid and chlorophyll losses.…”

“…Catalase activity was measured according to Chance and Maehly (1955) and Hildebrand et al (1986). Catalase activity was determined by measuring the decrease in absorbance that reßects the decomposition of hydrogen peroxide catalyzed by catalase.…”