Exploring the Dynamics of Defensive Traits Contributing to Aphid Resistance in Wild Emmer Wheat

Bread wheat is the second most important food crop proving calories to half of the world populations. Severe disease and damage due to insect pests led to huge losses of yield and posed serious threat the global food security. Three main factors of defense mechanisms determine resistant traits: i) physical barriers, ii) alteration in plant palatability and nutritional quality, and iii) chemical toxic metabolites. We hypothesis that the wild progenitors of modern bread wheat, offer different combinations of resistant traits to herbivorous insects that might have been lost due to genetic bottlenecks events of domestication. The aim of this study is to understand the relationships between the three factors of defense mechanisms by exploiting the wild emmer wheat panel. We investigate 200 accessions from the wild emmer wheat panel for aphid fecundity bioassay and quantify the trichome density which serves as a physical barrier, in conjunction with plants palatability (primary metabolite composition) in response to Rhopalosiphum padi aphid infestation. We observed the induction of aromatic amino acids, coordinated with the accumulation of salicylic acid signaling molecule, suggesting increasing plant defense in response to aphid infestations. By contrast, no correlation ship observed between trichome density and herbivore resistance. Our next step is to evaluate the levels and relationship of the chemical deterrent metabolites with the other two factors. Our work will contribute to exposing the untapped genetic resourced of wild emmer wheat for greater resistance diversity to insects that potentially provide the foundation for crop improvement.