An In Vitro Method for Identifying Postattachment Striga Resistance in Maize and Sorghum

Breeding for durable Striga resistance requires identification and stacking of multiple genetic barriers to parasitism in crops. This task would be greatly aided by having screening tools for identifying in parent sources and breeding populations resistance traits that function at various stages in the parasitic association. In this study, we describe a root observation system called the sand packed titer plate assay (SPTPA) used to study early postattachment development of Striga hermonthica (Del.) Benth. on two maize (Zeamays L.) and two sorghum [Sorghum bicolor (L.) Moench] inbred lines selected for field resistance and susceptibility to Striga. The resistant maize and sorghum lines had fewer Striga attachments and these showed delayed parasitic development, and higher mortality compared to those on susceptible cultivars. The SPTPA was useful in identifying specific resistance reactions to S. hermonthica in maize and sorghum and reflected results from field studies of these varieties. This assay would complement field testing during development of Striga-resistant varieties.