POPULATION-STRUCTURE, GENETIC DIVERSITY AND HOST-SPECIFICITY OF THE PARASITIC WEED STRIGA-HERMONTHICA (SCROPHULARIACEAE) IN SAHEL

Seed proteins of individual plants from 14 populations of Striga hermo nthica growing on sorghum, millet, maize and wild grasses in Burkina F aso, Mall and Niger were studied using gel electrophoresis in order to assess the population structure and genetic diversity of the parasiti c weed. The relative intensity of the different bands within a pattern was used to depict the genotypic constitution of each sample. Genotyp ic frequencies conformed to Hardy-Weinberg expectations in 13 populati ons out of 14 for the two loci that were interpreted. Heterozygote def iciencies could be the result of the Wahlund effect. The genetic diver gence between populations appears to be low for both Adh and Got loci. Thus, the physiological specialization for a particular host could be a recent phenomenon. A low host specificity of S. hermonthica populat ions could affect the efficiency of introducing new resistant cultivar s as a control measure against the parasitic weed.