Striga is a parasitic plant that feasts through the roots of corn, sorghum, upland rice, millet, and cowpea, devastating these crops and the lives of people who depend on them in sub-Saharan Africa and other areas in the developing world. The Food and Agriculture Organization of the United Nations (FAO) notes that, while maize has the largest acreage of all field crops in Africa, the average yield (1.6 t/hectare) is less than 1/3 of that achieved per unit area elsewhere in the world. The situation is further exacerbated by widespread dispersal of Striga seeds that intermix with maize kernels and ears going to market. This EAGER project will test a potentially novel strategy for dealing with Striga infestation using a newly identified transposon-induced (non-transgenic) mutant of maize. This plant carries a mutation in a gene that encodes a carotenoid cleavage dioxygenase 8 (ccd8) and has been shown to produce little to no precursors for strigolactone (SL), a maize hormone that is sensed by the Striga parasite and is required as a chemo-signal for host location and germination of its own seeds. The non-transgenic nature of this new maize mutant also enhances prospects for its acceptance and use by peoples with diverse cultures.
This project will test the extent to which actual interactions between maize and Striga are affected by the partially-understood roles of strigolactone in plant biology. The specific objectives are to: 1) determine the degree of resistance to Striga seed germination and host attraction offered by the ccd8 mutation, and 2) test the concept that a relatively modest yield penalty in ccd8 maize can be countered without losing Striga resistance, by breeding strategies based on hybrid vigor and naturally-occurring genetic modifiers. If successful, this EAGER project will provide for a new strategy that could counter Striga-based yield losses that extend from 15% to 100%, thereby making maize production sustainable in Striga infested regions.
