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Physiological responses of plants to piercing-sucking arthropods

Tulio Branco Macedo, University of Nebraska - Lincoln

Abstract

In 2001 and 2002, I examined physiological responses of different plant species to arthropod injury, in particular aphids, in greenhouse and field experiments. I examined changes in photosynthesis of wheat, Triticum aestivum L., to Russian wheat aphid, Diuraphis noxia (Mordvilko), and soybean, Glycine max (L.), in response to soybean aphid, Aphis glycines Matsumara. Results indicated that aphids were able to alter the source-sink relationship in injured leaf blades in a similar fashion across the plant species evaluated. Photosynthetic impairment was observed in both wheat and soybean plants challenged with low aphid pressure, either by short periods of exposure or by low densities. However, no significant reduction of pigments, chlorophyll and carotenoid, were observed, which suggested no direct relationship between aphid injury and pigment loss. Chlorophyll a fluorescence transient analysis indicated two possible mechanisms involved in the plant responses: (i) end-product inhibition of photosynthesis caused by source-sink manipulation elicited by feeding (with possible concurrent disruption of the CO2 assimilation on the dark reaction); or (ii) photo-inhibition on the light reactions due to an increase in activated oxygen species within the chloroplast through generation of triplet-chlorophyll in the pigment-protein complex concomitant with thylakoid membrane disruption. Biochemical evaluation of non-structural carbohydrate pools in injured leaves, through determination of concentrations of the reducing glucose sugar, shows significant increases in carbohydrate pools post injury. These findings indicated that plant photosynthesis was primarily affected by an accumulation of photosynthetic end-products, which in turn could trigger a series of inhibitory reactions throughout the photosynthetic apparatus. This work illuminates an immediate cause of photosynthetic reductions in plants fed upon by aphids, and suggests that a common mechanism of photosynthetic disruption may occur in plants that is induced by aphid feeding. ^

Subject Area

Biology, Botany|Biology, Entomology

Recommended Citation

Macedo, Tulio Branco, "Physiological responses of plants to piercing-sucking arthropods" (2003). ETD collection for University of Nebraska - Lincoln. AAI3098172.
http://digitalcommons.unl.edu/dissertations/AAI3098172

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