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.

Functional Characterization of HFR1, a High-MannoseN-Glycan-Specific Wheat Lectin Induced by Hessian Fly Larvae

“…In contrast to the rapid initiation of feeding by the virulent larvae, the avirulent larvae exhibited prolonged activity (Table II), as a gene-for-gene recognition event triggers increased mRNA levels of defense genes (Sardesai et al, 2005b) along with genes encoding lectins, such as Hfr-1 (Subramanyam et al, 2006) and Hfr-3 (Giovanini et al, 2007). The specific elicitation of these wheat lectins, which previously have not been linked to defense, suggests the targeted involvement of this class of proteins during resistance to Hessian fly.…”

“…No evidence of a classical oxidative burst has been detected in wheat following attack by virulent or avirulent Hessian fly larvae (Giovanini et al, 2006). In fact, several unique genes have been identified in wheat that are specifically elicited by the Hessian fly (Williams et al, 2002;Puthoff et al, 2005;Giovanini et al, 2007).…”

Mechanisms of plant defense against insect herbivores

“…69 Expression of a mannose-binding jacalin-like lectin called Hessian fly, Mayetiola destructor (Say) responsive protein 1 (HFR1), and two chimerolectin-like proteins called HFR2 and HFR3 have been reported to be induced by the larvae of Hessian fly, M. destructor in wheat. 70,71 Differences in feeding behavior of insects results in expression of different lectins, e.g., larvae of the fall armyworm, S. frugiperda induced HFR2, but not HFR3 expression while the phloem-feeding bird cherry-oat aphid, Rhopalosiphum padi Koch, induced HFR3 and HFR2, but latter was expressed much later (12 d) than the former (24 h). 70,72 Several jasmonate-inducible lectins are expressed in leaf tissues of monocots such as rice, barley, wheat, rye, and maize.…”

“…70,71 Differences in feeding behavior of insects results in expression of different lectins, e.g., larvae of the fall armyworm, S. frugiperda induced HFR2, but not HFR3 expression while the phloem-feeding bird cherry-oat aphid, Rhopalosiphum padi Koch, induced HFR3 and HFR2, but latter was expressed much later (12 d) than the former (24 h). 70,72 Several jasmonate-inducible lectins are expressed in leaf tissues of monocots such as rice, barley, wheat, rye, and maize. 73 Advancement of our understanding in induction of plant lectins in response to various stresses, especially herbivory, and their role in plant defense has the potential for utilization of these entomotoxic lectins in crop protection through genetic engineering.…”

Plant‐insect interactions: what can we learn from plant lectins?

“…After 192 h all larvae on resistant plants seemed to be dead, presumably through starvation (Subramanyam et al, 2008). Puthoff et al (2005) and Giovanini et al (2007) identified two more lectins with comparable expression patterns in wheat upon infestation with avirulent Hessian fly strains. Hfr-2 and Hfr-3 contain lectin domains similar to amaranthin and hevein, respectively.…”