Morphological and molecular profiling of Striga gesnerioides on cowpea in Ghana

This study accessed the morphological and molecular diversity of Striga gesnerioides populations from endemic regions of Northern Ghana. Morphological variations revealed the existence of two flower types: purple and white, with the purple being the major occurring type. The reaction of Striga populations on selected cowpea genotypes grouped the genotypes into three classes of which, 10 were resistant to all the population, 9 were susceptible to all the population and 8 showed differential response to the population. However, virulence study of the Striga population on these genotypes revealed three Striga clusters. Molecular diversity using newly designed markers showed that the markers were very informative with 73% being polymorphic. Principal Coordinate and Neighbour-joining analysis of molecular data grouped the Striga populations also into three clusters. However, population structure analysis resulted in five sub-populations with fixation index (Fst) values ranging from 0.0799 to 0.2533. The results obtained indicate the presence of multiple races of S. gesnerioides in Ghana. The identities of the races present are S. gesnerioides (SG) races 3, 2 and 5. The current study significantly broadens the information on the diversity and population structure of S. gesnerioides in the country and has established a new set of markers for S. gesnerioides fingerprinting. The study also identified cowpea varieties resistant to all collections of S. gesnerioides, which can serve as parents in the improvement of cowpea in Ghana and West Africa at large.