title: A novel wheat gene encoding a putative chitin-binding lectin is associated with resistance against Hessian fly.
abstract: SUMMARY The gene-for-gene interaction triggering resistance of wheat against first-instar Hessian fly larvae utilizes specialized defence response genes not previously identified in other interactions with pests or pathogens. We characterized the expression of Hfr-3, a novel gene encoding a lectin-like protein with 68-70% identity to the wheat germ agglutinins. Within each of the four predicted chitin-binding hevein domains, the HFR-3 translated protein sequence contained five conserved saccharide-binding amino acids. Quantification of Hfr-3 mRNA levels confirmed a rapid response and gradual increase, up to 3000-fold above the uninfested control in the incompatible interaction 3 days after egg hatch. Hfr-3 mRNA abundance was influenced by the number of larvae per plant, suggesting that resistance is localized rather than systemic. In addition, Hfr-3 was responsive to another sucking insect, the bird cherry-oat aphid, but not to fall armyworm attack, wounding or exogenous application of methyl jasmonate, salicylic acid or abscisic acid. Western blot analysis demonstrated that HFR-3 protein increased in parallel to mRNA levels in crown tissues during incompatible interactions. HFR-3 protein was detected in both virulent and avirulent larvae, indicating ingestion. Anti-nutritional proteins, such as lectins, may be responsible for the apparent starvation of avirulent first-instar Hessian fly larvae during the initial few days of incompatible interactions with resistant wheat plants.
authors.affiliation: Department of Agronomy, Purdue University, 915 W. State St., West Lafayette, IN 47907, USA.
authors.forename: Marcelo P
authors.initials: MP
authors.lastname: Giovanini
authors.forename: Kurt D
authors.initials: KD
authors.lastname: Saltzmann
authors.forename: David P
authors.initials: DP
authors.lastname: Puthoff
authors.forename: Martin
authors.initials: M
authors.lastname: Gonzalo
authors.forename: Herbert W
authors.initials: HW
authors.lastname: Ohm
authors.forename: Christie E
authors.initials: CE
authors.lastname: Williams