Genetic and phenotypic responses of temperature-independent Hessian fly-resistant durum wheat to larval attack during heat stress

Abstract Background Wheat production is increasingly challenged by the devastating damage caused by insect pests. The advent of global warming is further exacerbating this threat. Hessian fly (Mayetiola destructor), a dipteran gall midge, is a destructive pest of host wheat (Triticum aestivum) having severe economic consequences. Planting wheat cultivars harboring resistance genes is the most effective and economical Hessian fly management strategy. However, heat stress poses a challenge to this strategy, as elevated temperature often breaks down Hessian fly resistance in wheat. Our prior study identified temperature-independent resistant T. turgidum (durum wheat) accessions that maintained resistance to Hessian fly when challenged with an increased temperature of 30 °C. In this study, we carried out follow-up characterization of these durum lines to highlight molecular components involved during Hessian fly resistance or susceptibility in wheat following heat stress. Results Temperature-independent resistant durum lines were greater than 70% resistant to multiple Hessian fly biotypes at the elevated temperature of 30 °C. At the molecular level, these lines showed increased transcripts of Hfr-1, a gene encoding an antinutrient lectin, unlike the heat-triggered susceptible durum wheat. The Hessian fly susceptibility-associated biomarker genes were significantly upregulated in the durum wheat with heat-triggered susceptibility at 30 °C, resembling the gene expression profile observed in susceptible wheat. None of these susceptibility-associated genes were differentially expressed in the temperature-independent resistant wheat. Genes involved in oxidative stress and jasmonic acid pathways did not reveal any specific expression pattern attributed to either heat stress or larval feeding. Neutral red staining revealed limited cell wall permeability in the temperature-independent resistant wheat, unlike the heat-triggered susceptible durum plants that were highly permeable similar to a wheat line susceptible to Hessian fly at 20 °C. Conclusions Temperature-independent resistant durum wheat lines provided robust resistance to multiple Hessian fly biotypes at higher temperatures. These lines offer a valuable resource for wheat producers for providing resistance following heat stress.