Submitted to: International Wheat Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2005
Publication Date: 7/1/2005
Citation: Giovanini, M., Ohm, H., Williams, C.E. 2005. A gene (HFR-3) that encodes four chitin-binding domains is highly up-regulated during hessian fly larval feeding in resistant wheat plants. International Wheat Conference Proceedings. Interpretive Summary:
Technical Abstract: Newly emerged Hessian fly larvae feed on crown tissue of seedlings inducing permanent stunting on susceptible host plants. On resistant plants, larvae are unable to establish permanent feeding sites and consequently die after four days. The defense response is elicited due to a gene-for-gene recognition event between avirulent larval genotypes and resistant wheat genotypes. The molecular mechanisms of these interactions have not been elucidated. We have characterized a Hessian fly-responsive wheat gene that encodes a lectin (Hfr-3). Hfr-3 is highly up-regulated in resistant plants during the critical first four days of larval feeding. Q-RT-PCR data showed a 3000-fold up-regulation in the level of Hfr-3 mRNA in resistant plants challenged with avirulent Hessian fly larvae. The deduced amino acid sequence of this lectin is 70% identical to Wheat Germ Agglutinin (WGA) and has three putative chitin-binding domains. The expression profile of Hfr-3 in response to larval feeding fits well the annotated function of the HFR-3. The abundant increase in Hfr-3 mRNA from the beginning of larval feeding through the last day of feeding supports a function for this gene in which the binding of this lectin to a glycoprotein receptor in the digestive tract of the larvae would block absorption of nutrients and lead to death of the larvae via starvation.