Striga species are obligate hemi-parasitic weeds that parasitize the roots of rain-fed rice, maize, sorghum and millet in sub Saharan Africa, causing devastating yield losses. Effective control of Striga is essential for food security and poverty alleviation for subsistence farmers, but it remains elusive. The use of Striga-resistant varieties should form the cornerstone of integrated control programs, as resistance is recognized as sustainable and cost effective. However, their use is constrained by our limited of knowledge of the identity, genetic basis and mode of action of genes underlying resistance to different S. hermonthica populations (ecotypes) and by the potential for rapid evolution of virulence in the parasite. 

In this seminar I will describe how we identified the same major S. hermonthica-resistance Quantitative Trait Locus (QTL) on chromosome 12 of rice, using two different mapping populations. The resistant parent of each population was either Nipponbare or IR64, an O. sativa spp. japonica and O. sativa spp. indica, respectively. Bioinformatics analysis of the QTL regions of Nipponbare and IR64 showed that they were rich in genes encoding transposable elements, small peptides and a cluster of cell surface, Receptor-Like Protein (RLP) resistance genes, annotated as orthologs of genes conferring resistance to Verticillium wilt in tomato. I will present evidence (including the use of RNAi and CRISPR technologies to alter the expression of key genes) that one or more of the candidate RLP genes contributes to the broad-spectrum resistance of the rice varieties Nipponbare and IR64 to different ecotypes of S. hermonthica.  I will finish by discussing the possible mode of action of the RLP genes and their potential for use in breeding programs.

Professor Julie Scholes’ research is focused on understanding the physiological and molecular interactions between plants and their symbionts, particularly the root parasitic witchweeds of the genus Striga. These parasites infect the staple cereal crops of sub-Saharan Africa (SSA) causing devastating losses in yield. Prof Scholes’ research group exploits genomic, comparative genomic, quantitative genetic and molecular approaches to identify genes underlying resistance in cereals to different genetic ecotypes of Striga species and to identify virulence genes in the parasite. The aim of this work is to understand the molecular basis of host-parasite specificity, which is essential for delaying the evolution of virulence in the parasite and to enable predictive breeding of durable defence in cereals.  

Professor Scholes obtained her PhD in physiological and molecular plant pathology at the University of Wales in 1986 and then moved to Sheffield University to take up a Royal Commission for the Exhibition of 1851 Research Fellowship.  In 1987 she was awarded a Royal Society University Research Fellowship that she held until 1995.  She then accepted a position in the Department of Animal and Plant Sciences where she is Emeritus Professor of Plant and Microbial Sciences.