Host-Parasite Interactions Throughout the Striga Life Cycle, and their Contributions to Striga Resistance

Field screening for resistance to Striga has been slow and difficult, with only modest success. Successful Striga parasitism is dependent upon a series of chemical signals produced by its host. Interruption of one or more of these signals results in failure to establish parasitism. We have embarked upon a programme a characterizing these signals, developing simple laboratory assays for them; identifying genotypes which are resistant because they produce abnormal levels of signals; elucidating the mode of inheritance to genotypes with high yield potential and broad adaptation. Focusing on the initial stage, the signal required for Striga seed germination, our collaborative research work in sorghum has resulted in the development of elite sorghum genotypes which combines Striga resistance with yield potential and good quality characteristics. These germplasm are currently under wide international testing in several African countries. We hope to follow this pattern for each host-dependent step in the development of Striga plants, then pyramid the resulting resistance genes into a single genotype which should exhibit durable, broad-based resistance.