Submitted to: NCB-ESA North Central Branch Entomological Society of America
Publication Type: Abstract only
Publication Acceptance Date: 3/30/2005
Publication Date: 3/30/2005
Citation: Giovanini, M., Ohm, H., Williams, C.E. 2005. The role of a highly induced lectin in the defense mechanism of resistant wheat during response to hessian fly larval feeding. NCB-ESA North Central Branch Entomological Society of America. URL: http://esa.ent.iastate.edu/confreg/?gridaction=viewonepresentation&year=2005&presnum=201&q=giovanini Interpretive Summary:
Technical Abstract: The Hessian fly neonate larvae feed on the crown tissue of seedlings inducing a permanent stunting phenotype 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. However, the molecular mechanisms of these interactions have not been elucidated. We have cloned a novel responsive wheat lectin gene to Hessian fly larval feeding (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 increase in the level of Hfr-3 mRNA in resistant plants challenged with Hessian fly larvae. This result was confirmed by quantitative northern blots using the RACE 5’ clone sequence as probe. 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 leads to the idea that binding of this lectin to a glycoprotein receptor in the digestive tract of the larvae would provoke a local or systemic deleterious effect which would cause death of the larvae. Experiments are in process to evaluate the involvement of this lectin as the major mechanism of wheat resistance to the Hessian fly.