Submitted to: Journal of Economic Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/23/2007
Publication Date: 10/1/2007
Citation: Franzen, L., Heng-Moss, T., Higley, L., Sarath, G., Burd, J.D. 2007. Physiological and biochemical responses of resistant and susceptible wheat to the russian wheat aphid, Diuraphis noxic (Mordvilko). Journal of Economic Entomology. 100: 1692-1703. Interpretive Summary: Plants respond differentially towards insect pests. Understanding the physiological bases for these differences can result in developing more resistant plants. In this study, the photosynthetic responses of susceptible and resistant wheat cultivars infested with the Russian wheat aphid were evaluated. Our results indicate that resistant plants maintain photosynthetic activity whereas susceptible plants show enhanced leaf senescence, suggesting that resistant plants are able to overcome insect-induced changes in leaf function.
Technical Abstract: How insect herbivores alter plant physiology is often unknown, so not surprisingly the interaction of insect resistance with herbivore injury is similarly uncertain. To address these issues, we examined physiological responses of resistant (‘Halt’ and ‘Prairie Red’) and susceptible (‘TAM 107’) wheat, Triticum aestivum L., to Russian wheat aphid, Diuraphis noxia (Mordvilko), injury by measuring assimilation/internal CO2 (A/Ci) curves, chlorophyll fluorescence, chlorophyll and protein content, peroxidase specific activity, and non-structural carbohydrate content. No significant differences were detected in chlorophyll content between control and infested ‘TAM 107’ plants, while resistant plants had chlorophyll levels similar or greater than control plants. Measurements over time showed that infested ‘Halt’ plants had delays in photosynthetic senescence, ‘Prairie Red’ plants had photosynthetic rate changes that were similar to control plants, and ‘TAM 107’ plants displayed accelerated photosynthetic senescence patterns. Photochemical quenching was significantly different between treatments for ‘TAM 107’ plants, but chlorophyll fluorescence responses were similar between treatments for resistant plants. Results here agreed with previous studies, indicating that photosynthetic declines from aphid injury were associated with mesophyll limitations, indicated by declines in carboxylation efficiency and RuBP regeneration. Differences between physiological responses of infested susceptible and resistant cultivars, particularly temporal changes in photosynthetic activity, imply that resistant cultivars ‘Halt’ and ‘Prairie Red’ tolerate some impacts of aphid injury on photosynthetic integrity.