Scientists from the Mexico-based International Maize and Wheat Improvement Center (CIMMYT) will announce next week that they have developed new varieties of wheat that are resistant to UG99, a virulent new form of black stem rust that is spreading rapidly from East Africa and threatening the world’s wheat supply. The research will be presented at a ‘technical workshop’ of the Borlaug Global Rust Initiative, an international consortium to tackle the threat of new crop pathogens set up in 2005 by Norman Borlaug, the father of the green revolution. Borlaug had already taken on stem rust in the past, succeeding in breeding high-yielding, rust-resistant wheat in the 1950s and 1960s, after the pathogen had claimed 40 percent of the wheat crop in the US and Canada. It is estimated that 90% of the world’s wheat now uses the Sr31 gene introduced by Borlaug to confer resistance to stem rust and is now susceptible to UG99, the new race of Puccinia graminis tritici, the fungus responsible for black stem rust. First identified in Uganda, UG99 spores are rapidly dispersed in the wind and, according to David Hodson of the Global Cereal Rust Monitoring System at the Food and Agriculture Organization of the United Nations (FAO), “Future spread of these variants outside of Africa is inevitable". The new CIMMYT varieties are based on the introduction of several ‘minor’ resistance genes into CIMMYT’s wheat stocks, an outcome of a breeding experiment on a grand scale involving about 2 million wheat plants grown in field sites in Mexico and Kenya. The hard graft of the plant breeding done, Ravi Singh who led the CIMMYT research is now calling for political support for the introduction of the new varieties: “We need to see national governments making the investments in seed systems development, including seed production and distribution. In many areas there will need to be support and leadership from wealthy countries and international institutions to carry these innovations into farmers' fields."
