Food security

StrigaPlant scientists at the University of Sheffield are coordinating an international effort to develop a strain of rice that can resist one of the world’s most devastating crop parasites to bring greater food security to millions of people in Africa.

The team, led by Professor Julie Scholes of the Department of Animal and Plant Sciences, has been set the challenging task of developing new cultivars of rice that can withstand attack by the Striga parasite which infects more than 40% of the upland rice crop in Africa.

‘We have a very strong inter-disciplinary and international team including researchers in the UK, Tanzania, Kenya, Uganda and Columbia,’ says Professor Scholes, who is one of the world’s leading authorities on what is commonly known as ‘witchweed’ that affects the food supplies of more than 100 million people around the globe.

‘I have been working on Striga for the last 15 years trying to understand how this parasitic weed has such a devastating effect on crop yield, and how we can improve the resistance of crops such as rice, millet and maize in cultivars that the farmers can grow to improve grain yields.

‘At Sheffield we have a fantastic plant growth environment in the Sir David Read Controlled Environment Facility. It is a stunning resource and it allows us to grow thousands of plants which we can then infect with the parasite in order to quantify their resistance response.

‘This parasite attaches itself to the roots of all the staple crops of sub-Saharan Africa and causes the plants to become stunted very rapidly. Striga has evolved in a very clever way, it won’t germinate in the soil unless there is a host plant there ready to infect. It knows this by detecting a chemical that is exuded from the roots of the host plant. Otherwise the parasite can remain dormant in the soil for up to 30 years,’ Professor Scholes said.

‘The FAO and the United Nations have estimated that over 70 million hectares of cereal growing land in Africa is infested with the seed of this parasite, which looks just like dust. They produce millions of seeds just from a few flower spikes, which just go back in to the soil to perpetuate this problem.

‘Ultimately the only way to control this parasite will be through a combination of strategies rather than just one. My role is to try and identify cultivars of rice that are resistant to Striga; to work out why they are resistant; what the genes are that make them resistant so that we can utilise that information to transfer those genes by marker assisted breeding into cultivars that the farmers want to grow. While this is not a transgenic technology, it is using modern molecular techniques to speed up traditional breeding processes, so we can transfer them quickly from one cultivar to another.’

Professor Scholes’ work on Striga is funded by a grant from the Biotechnology and Biological Sciences Research Council (BBSRC) under the Sustainable Crop Production Research for International Development (SCPRID) programme, a joint multi-national initiative of BBSRC and the UK Government's Department for International Development (DFID), together with (through a grant awarded to BBSRC) the Bill & Melinda Gates Foundation (BMGF), and the Department of Biotechnology (DBT) of India's Ministry of Science and Technology. This £16 million initiative harnesses the brain power of some 40 international research organisations with the aim of improving the performance of key crops in some of the poorest and most vulnerable societies on earth.

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