Antioxidant defense response in a galling insect

Abstract

Herbivorous insect species are constantly challenged with reactive oxygen species (ROS) generated from endogenous and exogenous sources. ROS produced within insects because of stress and prooxidant allelochemicals produced by host plants in response to herbivory require a complex mode of antioxidant defense during insect/plant interactions. Some insect herbivores have a midgutbased defense against the suite of ROS encountered. Because the Hessian fly (Mayetiola destructor) is the major insect pest of wheat worldwide, and an emerging model for all gall midges, we investigated its antioxidant responses during interaction with its host plant. Quantitative data for two phospholipid glutathione peroxidases (MdesPHGPX-1 and MdesPHGPX-2), two catalases (MdesCAT-1 and MdesCAT-2), and two superoxide dismutases (MdesSOD-1 and MdesSOD-2) revealed high levels of all of the mRNAs in the midgut of larvae on susceptible wheat (compatible interaction). During development of the Hessian fly on susceptible wheat, a differential expression pattern was observed for all six genes. Analysis of larvae on resistant wheat (incompatible interaction) compared with larvae on susceptible wheat showed increased levels of mRNAs in larvae on resistant wheat for all of the antioxidant genes except MdesSOD-1 and MdesSOD-2. We postulate that the increased mRNA levels of MdesPHGPX-1, MdesPH-GPX-2, MdesCAT-1, and MdesCAT-2 reflect responses to ROS encountered by larvae while feeding on resistant wheat seedlings and/or ROS generated endogenously in larvae because of stress/ starvation. These results provide an opportunity to understand the cooperative antioxidant defense responses in the Hessian fly/ wheat interaction and may be applicable to other insect/plant interactions.Hessian fly ͉ insect/plant interaction ͉ reactive oxygen species ͉ wheat

Ghrelin effects on midgut tissue antioxidative defense and glutathioneS-transferase activity in Lymantria dispar (Lepidoptera)

“…GSH prevents damage to important cellular components caused by ROS, such as free radicals and peroxides. Scientific publications indicate that insects with a higher resistance to trophic stressors are characterized by an increased level of glutathione and higher SOD, CAT, GR, and GST constitutive activities in comparison to stresssusceptible organisms (Bi and Felton, 1995;Felton and Summers, 1995;Perić-Mataruga 1997, 2000Mittapalli et al, 2007). In our experiments, we found that GR and GST activity was higher in ghrelin-treated Lymantria dispar larvae than in the control group (Figures 6 and 7).…”

Functional Characterization of HFR1, a High-MannoseN-Glycan-Specific Wheat Lectin Induced by Hessian Fly Larvae

“…Genetically, the virulent and avirulent Hessian fly larvae in our experiments were identical (biotype L), but their transcriptomes (Mittapalli et al, 2007a(Mittapalli et al, , 2007b(Mittapalli et al, , 2007c and behaviors diverged rapidly due to changes induced in them by different cues from their resistant and susceptible host plants. One important difference was that although the mRNA and protein levels of HFR1 were higher in resistant plants (Subramanyam et al, 2006; Fig.…”

“…One-way ANOVA was carried out using SAS, and all differences were considered significant at P , 0.05. presumed to function in an attempt to detoxify wheat allelochemicals (Mittapalli et al, 2007b). In addition, avirulent larvae experience oxidative stress, manifested as elevated levels of superoxide dismutase mRNA (Giovanini et al, 2006) along with phospholipid glutathione peroxidase mRNA (Mittapalli et al, 2007a). By 24 h after egg hatch, avirulent larvae exhibited two unusual behaviors that were never seen in virulent larvae: writhing (Supplemental Video S3) and head rearing (Table II; Supplemental Fig.…”

Unraveling the Tapestry of Networks Involving Reactive Oxygen Species in Plants

“…Egan et al (2007) reported that the generation of ROS by the rice blast fungal NADPH oxidase is required for infection, whereas Molina and Kahmann (2007) documented that activation of ROS scavenging mechanisms by the fungal Ustilago maydis Yap1 gene is essential to overcome the plant defense mechanisms and allow infection. In addition, Mittapalli et al (2007) reported that the ROS scavenging mechanisms of the Hessian fly (Mayetiola destructor) could play an important function in the interaction with its wheat (Triticum aestivum) host.…”