Mechanisms of wheat defense against the Hessian fly

Marcelo Prudencio Giovanini, Purdue University

Abstract

Wheat responses to Hessian fly larval attack are triggered by gene-for-gene recognition events that lead to resistance or susceptibility. The molecular mechanisms of this interaction are now becoming better understood. To gain more insights, we assayed Hessian fly-challenged wheat plants for active oxygen species production and characterized genes contributing to an oxidative burst. We demonstrated that oxidative burst does not play a role in the wheat resistance to Hessian fly. However, larval detoxification responses appear to fight against alternative stress mechanisms imposed by the plant. We found a wheat flavanone 3-hydroxylase gene, responsive to larval attack, which may be involved in the production of pro-oxidant molecules that would cause the larval stress. We characterized the expression of Hfr-3, a novel gene encoding a lectin-like protein with four predicted hevein chitin-binding domains, each with five conserved saccharide-binding amino acids. Hfr-3 is highly responsive to avirulent larval attack and both Hfr-3 mRNA and HFR-3 protein accumulated in the crown tissue of attacked resistant plants. The protein was ingested by the larvae, suggesting an antinutritional property that supports the apparent starvation of avirulent first-instar Hessian fly larvae. In addition, strategies used by virulent larvae to render wheat plants susceptible were suggested by the finding that a wheat Lipid transfer protein gene is repressed. We propose that repressing this LTP results in reduction of cutin deposition during development of nutritive tissue, which facilitates nutrient delivery to the developing larvae.

Degree

Ph.D.

Advisors

Williams, Purdue University.

Subject Area

Agronomy|Botany

COinS