Unveiling the Ecotype-Driven Virulence Heterogeneity Among Major Ecotypes of the Striga hermonthica Population from Ethiopia

Striga hermonthica, a root hemiparasitic weed, severely limits sorghum production in Sub-Saharan Africa. The use of resistant varieties is a widely adopted strategy for controlling Striga. To develop durable Striga-resistant sorghum varieties, this study investigates the interaction effects between host and parasite, as well as the virulence levels of five Ethiopian Striga ecotypes. A pot trial was conducted using seven resistant sorghum varieties, two susceptible checks, and five Ethiopian Striga ecotypes. Valuable data were generated on the interaction effects between sorghum varieties and Striga ecotypes based on three resistance indices: Striga count, Striga length, and dry Striga biomass. The findings revealed variability in sorghum responses to Striga infection, with a significant interaction effect between Striga ecotypes and sorghum varieties. Notably, the virulence levels of Striga ecotypes varied considerably across sorghum varieties; an ecotype highly virulent to one variety exhibited reduced virulence to another. Similarly, a sorghum variety highly resistant to one ecotype showed moderate or lower resistance to others. The variety Framida generally exhibited high levels of infection, whereas N‑13 demonstrated durable resistance. Importantly, sorghum varieties N‑13 and SRN39 consistently showed resistance across all tested ecotypes, making them prime candidates for strategic gene pyramiding. This study highlights the presence of interaction effects, which are critical for designing effective breeding strategies in future Striga resistance improvement programs. Furthermore, comprehensive studies on the genetic variability of Ethiopian Striga ecotypes will facilitate the development of durable resistant varieties.