Issn: 1992-1705

Striga hermonthica is a widely spread root parasitic weed on cereals in Sub Saharan Africa including Sudan. The most important hosts comprise sorghum, millet and sugar cane. Host specificity and existence of two distinct strains on sorghum and millet were previously reported. Reports on a third strain specific to maize are controversial. The present study was undertaken to investigate anatomical and genetic variability within S. hermonthica populations and their role in host-specificity. Striga seeds were collected from under sorghum, millet and maize. Anatomical variability within populations was based on response of host to infestation with different S. hermonthica strains and sustainable development of the parasite on sorghum, millet and maize. Genetic diversity was assessed by Amplified Fragment Length Polymorphism (AFLP) technique. The results showed anatomical differences in response to cross infestation at the attachment and penetration. The millet represents some defense mechanisms to the other strains that make it specific and it can indicate diversity or account for the observed intercrop specificity within S. hermonthica populations. Unweighted pair group method (UPGMA) cluster analysis revealed two distinct clusters of S. hermonthica populations. Genetic distances for S. hermonthica populations ranged from 0.03 to 0.09 (0.03 for populations collected from under maize and sorghum, 0.05 for populations collected from under maize and millet and 0.09 for populations collected from under sorghum and millet). AFLP marker with three primer pairs confirmed the close relation between sorghum and maize strains. The millet strain slightly differed and was more specific to its host.