Gene-for-Gene Defense of Wheat Against the Hessian Fly Lacks a Classical Oxidative Burst

Abstract

Genetic similarities between plant interactions with microbial pathogens and wheat interactions with Hessian fly larvae prompted us to investigate defense and counterdefense mechanisms. Plant oxidative burst, a rapid increase in the levels of active oxygen species (AOS) within the initial 24 h of an interaction with pathogens, commonly is associated with defenses that are triggered by gene-for-gene recognition events similar to those involving wheat and Hessian fly larvae. RNAs encoded by Hessian fly superoxide dismutase (SOD) and catalase (CAT) genes, involved in detoxification of AOS, increased in first-instar larvae during both compatible and incompatible interactions. However, mRNA levels of a wheat NADPH oxidase (NOX) gene that generates superoxide (O2-) did not increase. In addition, inhibiting wheat NOX enzyme with diphenyleneiodonium did not result in increased survival of avirulent larvae. However, nitro blue tetrazolium staining indicated that basal levels of O2- are present in both uninfested and infested wheat tissue. mRNA encoded by wheat genes involved in detoxification of the cellular environment, SOD, CAT, and glutathione-S-transferase did not increase in abundance. Histochemical staining with 3,3-diaminobenzidine revealed no increases in wheat hydrogen peroxide (H2O2) during infestation that were correlated with the changes in larval SOD and CAT mRNA. However, treatment with 2',7'-dichlorofluorescin demonstrated the presence of basal levels of H2O2 in the elongation zone of both infested and uninfested plants. The accumulation of a wheat flavanone 3-hydroxylase mRNA did show some parallels with larval gene mRNA profiles. These results suggested that larvae encounter stresses imposed by mechanisms other than an oxidative burst in wheat seedlings.

Reactive Oxygen Species Are Involved in Plant Defense against a Gall Midge

“…In contrast to extensive evidence for a major role of ROS in plant defense against pathogens (Lamb and Dixon, 1997), evidence for a role of ROS in plant defense against insects is still preliminary, sporadic, and inconsistent (Giovanini et al, 2006;Moloi and van der Westhuizen, 2006;Chen, 2008). In this research, accumulation of ROS at the attack site in three isogenic wheat lines, Newton, Iris, and Molly, and the rice line Nipponbare was examined following Hessian fly infestation.…”

“…The activity of NADPH-dependent oxidases and the increase in H 2 O 2 concentration in resistant plants following Russian wheat aphid (Diuraphis noxia) infestation (Moloi and van der Westhuizen, 2006) suggest that NADPH-dependent oxidases are involved in ROS generation in plants as a response to insect attack. However, mRNA levels of a NADPHdependent oxidase and several genes encoding ROSscavenging enzymes were not significantly altered in resistant wheat seedlings in response to Hessian fly attack, indicating that either ROS levels do not increase or an alternative mechanism for ROS generation is active following Hessian fly attack (Giovanini et al, 2006).…”

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

“…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.…”

“…Classical pathogenesisrelated and other defense-response genes associated with plant-pathogen interactions are minimally responsive in resistant wheat during Hessian fly larval attack (Sardesai et al, 2005b). No evidence of a classical oxidative burst has been detected in wheat following attack by virulent or avirulent Hessian fly larvae (Giovanini et al, 2006). In fact, several unique genes have been identified in wheat that are specifically elicited by the Hessian fly (Williams et al, 2002;Puthoff et al, 2005;Giovanini et al, 2007).…”

Differently expressed ‘Early’ flavonoid synthesis genes in wheat seedlings become to be co-regulated under salinity stress

“…In bread wheat (Triticum aestivum), the synthesis of flavonoids can be induced by e.g. Hessian fly infestation, salinity, drought, and low temperature stress (Giovanini et al 2006;Olenichenko et al 2006Olenichenko et al , 2008Tereshchenko et al 2012;Ma et al 2014). A comparison between near-isogenic wheat lines has suggested a correlation between drought tolerance and the intensity of pigmentation of the coleoptile and pericarp produced by anthocyanins (Tereshchenko et al 2012).…”