BREAD: Engineering Novel Resistance against Fungal and Oomycete Pathogens in Developing Country Crop Plants

PI: Brett Tyler (Virginia Polytechnic Institute and State University)

CoPIs: Shunyuan Xiao (University of Maryland Biotechnology Institute) and Mark Guiltinan (Pennsylvania State University)

Collaborator: Brian Bailey (USDA-ARS Sustainable Perennial Crops Lab, Beltsville, Maryland)

Small-holder agriculture in developing countries is exceptionally susceptible to fungal and oomycete disease due to lack of local breeding programs, tropical climate, abundant insect vectors, cost of and poor access to fungicides, and lack of farmer education. Small-holder farmers in Africa and South America are responsible for more than 95% of cacao production, providing economic benefits to millions of cacao farmers and their dependents, as well as important ecological benefits such as rain-forest preservation. Fungal and oomycete diseases have devastated cacao production in South America and West Africa, dislocating populations of farmers and resulting in destruction of the rain-forest sheltering the cacao trees in favor of large-scale open farmland. This project will test two novel approaches to protecting developing country crops against a broad-spectrum of oomycete and fungal pathogens, using cacao as the initial target. The first involves targeting anti-microbial proteins to pathogen feeding structures called haustoria, using RPW8, an Arabidopsis protein that has a natural affinity for these feeding sites. The second approach involves blocking the entry of virulence proteins (effector proteins) that pathogens secrete into host cells to suppress the plant host's immune system. The most effective strategies will be identified first using fast growing Arabidopsis and tomato plants before being tested in cacao.

Broader Impacts: The novel technologies that will be tested in this project are potentially applicable to an extremely broad array of crop diseases important to the developing world. The most destructive diseases of broad acreage staples such as rice and wheat are potentially amenable to this approach, as are many of the most limiting fungal and oomycete diseases of crops of importance to smallholders, such as yams, cassava, groundnuts, pearl millet, finger millet, sorghum, maize, potato, bean and cowpea. The project includes visits from scientists from developing countries, a colloquium in Ecuador, and regular communication with scientists from cacao-producing countries. Project outcomes as well as access to biological resources that include DNA constructs and germplasm will be disseminated through a project website (accessible via https://www.vbi.vt.edu/faculty/research_groups/brett_tyler) and through publications.