Signal transduction pathways of the oxidative burst

Sreeganga Sharat Chandra, Purdue University

Abstract

The oxidative burst is a rapid, localized plant defense response. It involves the production of millimolar quantities of $\rm O\sb2\sp{-\cdot}/H\sb2O\sb2$ that serves both as a microbicidal agent and a second messenger within the plant. The focus of this research is to elucidate the signal transduction pathways that control this plant defense response. To achieve this goal, we have taken a three pronged approach: (1) to identify chemically pure elicitors of the oxidative burst, (2) to elucidate the second messengers by which the various elicitors operate, and (3) study desensitization among the various elicitor induced bursts. Previously, oligogalacturonic acid, a cell wall component, and a glycoprotein from the fungus Verticillium dahliae had been shown to be elicitors of the oxidative burst. I have continued this work and shown that harpin, a protein from Erwinia amylovora, fensulfothion, an organophosphorous insecticide and hypo-osmotic stress are also potent inducers of the burst. I have also identified several second messengers involved in these elicitor induced bursts, including activation of phospholipase A, changes in protein phosphorylation and Ca$\sp{2+}$ fluxes. Finally, I have examined both homologous and heterologous desensitization amongst the various elicitor induced bursts. This study has helped to identify signaling events that control this important plant defense response.

Degree

Ph.D.

Advisors

Low, Purdue University.

Subject Area

Biochemistry|Plant pathology|Botany

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