Durable Rice Blast Resistance for Sub-Saharan Africa

Rice consumption in sub-Saharan Africa is growing faster than for any other crop species, driven by consumer preference and rapid urbanisation. Rice production depends predominantly on smallholder farmers and cannot meet the increasing demand for rice. Locally adapted, high yielding rice cultivars have been developed but are very sensitive to a devastating disease called rice blast. Every year, rice blast disease destroys enough rice to feed 60 million people worldwide and crop losses in Africa to this disease often exceed 60%. This project is designed to develop and deploy durable rice blast resistant rice varieties to smallholder farmers in sub-Saharan Africa.

The project builds upon extensive collaboration between the project partners over the last four years through a BBSRC Sustainable Crop Production for International Development (SCPRID) award. In this previous work, we have used knowledge of the diversity of the pathogen that causes rice blast disease to guide rice breeding programmes. We have generated new, locally adapted, high yielding rice cultivars with new disease resistance specificities that are now ready to be tested across sub-Saharan Africa.

In this project, we will test the reliability of the new cultivars in disease hotspots in 19 sites within 7 African countries- Kenya, Tanzania, Burundi, Burkina Faso, Cote d'Ivoire, Rwanda and Madagascar. We will test if these new rice varieties are able to resist the disease in such diverse settings and different rice production systems, including upland, irrigated and rained lowland farms. We will use this information to register these varieties for free release to farmers. We will also continue to develop a pathogen surveillance programme, established by previous BBSRC funding to guide our ongoing rice breeding work in the Cote d'Ivoire, Kenya and Burkina Faso. We will breed further rice varieties in which we will incorporate different resistance specificities, guided by the prevailing blast pathogen population.

Finally, but very importantly, we will undertake an extensive series of farmer engagement activities, plant disease clinics, and further development of information resources to allow rapid deployment and take-up of the new rice varieties generated in this project. We will provide practical advice immediately to farmers, allow them to be fully engaged in testing the new varieties being developed and provide a network of plant clinics to advise them on a range of disease issues. Taken together, the project will allow sustainable intensification of rice production in Africa, providing much great food security to the region and impacting on the economic wellbeing of many thousands of small holder farmers in sub-Saharan Africa.

The project aims to develop and deploy durably rice blast resistant rice varieties for sub-Saharan Africa. In previous BBSRC-funded work we identified two race specific broad-spectrum Resistance genes, Pi9 and Pi2-A15, that would exclude the majority of the rice blast pathogen population in sub-Saharan Africa. We introgressed these loci into 4 elite rice varieties; Basmati 217, Basmati 370, NERICA2, and NERICA12 via marker assisted backcrossing and distributed them to breeders in Kenya and Burkina Faso. We will carry out disease hotspot testing in multiple sites within 7 countries; Kenya, Burkina Faso, Côte d'Ivoire, Rwanda, Burundi, Tanzania, and Madagascar to test their durability. In addition to race specific R genes, 3 non-race specific R genes pi21, Pi35, and Pi-A35 were also introgressed and will be rigorously tested for disease resistance.

We will then carry out enrichment and curation of the sub-Saharan Africa blast disease surveillance system by collection and genotypic analysis of a further 2400 Magnaporthe oryzae isolates. Pathotype assignments and genotyping will be used to monitor the prevalence of new virulent strains of the fungus across Africa and identify the avirulence genes and cognate disease resistance genes that could control the prevailing blast population.

We will be guided by the ongoing pathogen surveillance system and undertake further rice breeding. Initially, we will focus on combining different resistance specificities. We will focus initially on pyramiding of Pi2-A15/Pi35/pi21 and Pi9/Pi35/pi21 in 2 different rice varieties, Basmati 370 and NERICA 2 and providing breeding lines for further gene combinations in these high yielding, popular cultivars.

Finally, we will undertake extensive farmer engagement through training of Plant Doctors- extension professionals skilled in guiding farmers in disease control -and undertaking Plant Clinics to provide local advice and engagement in new variety release.

Immediate outputs of this project research will be in the form of technologies, training, knowledge and processes. An important package of scientific information is already available from the BBSRC funded SCPRID project. The next stage will focus on transforming this knowledge into technologies such as new rice cultivars, that are highly resistant to blast, disease survey kits for monitoring blast in sub-Saharan African countries and training farmers and extension workers in disease management.

The project is designed to develop and deploy durable rice blast resistant rice cultivars to smallholder farmers in sub-Saharan Africa. It therefore has a very strong impact component. Indeed, almost all of the activities described in the project have an impact element to them, given that the overriding aim of the project is to produce new varieties of rice that smallholder farmers across Africa will grow and that consumers will buy.

The project will involve extensive farmer engagement activities, including training of plant doctors, who are local advisors in plant health, as well as a nationwide series of plant clinics that will take place across Kenya, before dissemination to further countries, such as Tanzania. These activities will provide advisory services at the farm level throughout the country and significantly expand the current plant clinic networks.

There is also a significant capacity building element to the project which will help to train a new generation of scientists in Sub-Saharan Africa to characterize pathogen diversity, identify effective resistance genes in rice, and determine how best to manage rice blast disease through effective and sustainable deployment of disease resistance.