Molecular Characterisation of Striga hermonthica Populations from Major Agricultural Regions of Niger

Abstract

Striga hermonthica is one of the most destructive parasitic weeds affecting cereal production in sub-Saharan Africa, particularly in Sahelian agricultural systems. Despite its major impact, information on the genetic diversity of S. hermonthica in Niger remains limited. This study assessed the genetic diversity and population structure of 25 S. hermonthica ecotypes from five major agricultural regions of Niger using five microsatellite (SSR) markers. The results reveal substantial genetic diversity among the S. hermonthica characterised. All loci were polymorphic, with regional polymorphism rates ranging from 60% to 100%. The mean observed heterozygosity (Ho = 0.530) exceeded the expected heterozygosity (He = 0.344), resulting in a negative inbreeding coefficient (F = -0.442) and indicating an excess of heterozygotes and deviation from Hardy-Weinberg equilibrium. Moderate genetic differentiation among regions was detected (mean Fst = 0.167), suggesting structured populations influenced by geographic origin. Cluster analyses consistently separated genotypes from the Dosso region from those of the other regions, while closer genetic relationships were observed between Tahoua and Tillabéry, and between Maradi and Zinder. These findings provide a valuable genetic baseline for understanding the adaptive potential of the species and support the development of region-specific and sustainable management strategies against this parasitic weed.