A novel wheat gene encoding a putative chitin-binding lectin is associated with resistance against Hessian fly |
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Authors: | MARCELO P. GIOVANINI,KURT D. SALTZMANN,DAVID P. PUTHOFF &dagger ,MARTIN GONZALO,HERBERT W. OHM, CHRISTIE E. WILLIAMS |
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Affiliation: | Department of Agronomy, Purdue University, 915 W. State St., West Lafayette, IN 47907, USA; USDA-ARS Crop Production and Pest Control Research Unit, West Lafayette, IN 47907, USA; Department of Entomology, Purdue University, 901 W. State St., West Lafayette, IN 47907, USA |
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Abstract: | 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. |
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