UNDERSTANDING AND ENGINEERING HOST DEFENSE TO A PARASITIC PLANT

Parasitic plants are major limiting factors for crop production in many parts of the world and threaten to expand invasions in the US. These plants are especially damaging weeds because they directly invade host plants through a physical bridge (the haustorium), resulting in host water and nutrients being redirected into the parasite. As an extreme form of plant-plant interaction, host-parasitic plant communication has received increasing attention from researchers, but little progress has been made in achieving the ultimate goal of creating parasite-resistant host crops. Just as plants respond to plant-pathogen attack, they react to parasitic plants, but the defenses deployed are rarely effective. We hypothesize that host defense systems can be improved to generate resistant crops.We have evidence that host defense signaling networks influence the success of the parasitic plant Phelipanche aegyptiaca (Egyptian broomrape) attachment on host roots. We will use genetic and molecular tools to dissect the role of host defense genes in the interaction between the model plant Arabidopsis and the parasite. We will also identify and optimize host gene promoters that are highly specific to the region of parasite attack. We will then generate transgenic plants expressing these promoters fused to the most effective defense genes. Ultimately, we will generate enhanced resistance in tomato, a crop widely affected by this parasite. This project will expand our understanding of host defense responses and host-parasitic plant communication, which directly addresses program priorities in studying interactions of crops with plant pests, and the impact of defense signaling on pests.