Identifying resistance in rice to the parasitic witchweeds, Striga hermonthica and Striga. asiatica

Professor Julie Scholes
University of Sheffield
Understanding the molecular genetic basis of resistance in rice to Striga hermonthica and S. asiatica.


The parasitic witchweeds Striga hermonthica and S. asiatica cause devastating losses in the yields of upland rice across sub Saharan Africa. Good control of Striga has not yet been achieved and reducing yield losses due to Striga is essential for food security and poverty alleviation. The use of resistant cultivars in Striga control programmes is limited by a lack of knowledge of the identity and genetics of both host resistance and parasite virulence genes.

My research group uses, genomic, quantitative genetic and molecular approaches to identify genes in rice underlying resistance to different genetic accessions of the two Striga species. We collaborate extensively with Dr Mathias Lorieux a geneticist based at CIAT, Colombia and IRD Montpellier, France. By phenotyping Recombinant Inbred Line  (RIL) populations of rice (developed by Dr Lorieux) for resistance to different accessions of S. hermonthica and S. asiatica, we are identifying genes that have different modes of action. This will allow stacking of combinations of genes in farmer preferred rice varieties to improve the durability of resistance. As well as working at a molecular level we also work with scientists at Africa Rice to carry out field trials of a wide diversity of rice germplasm in farmer’s fields in sub Saharan Africa, to identify varieties that are of immediate use to farmers and plant breeders.

We are also identifying virulence genes in different accessions of S. hermonthica and S. asiatica using population genomic and comparative sequencing approaches, to better understand the molecular genetic basis of host-parasite specificity.  This is essential for delaying the evolution of virulence in the parasite and to enable predictive breeding of durable defence in rice.