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- In a world economy faced with global food insecurity the demand for increased agricultural production has never been greater. This demand is set against a background of declining natural resources, increasing land marginalisation and the uncertainties of climate change. The development of low-chemical input, sustainable agricultural systems is therefore critical. Along with rice and maize, wheat provides a substantial proportion of the calorific intake of the human population. Biotic stresses present a major constraint to crop production, with the fungal rusts of wheat being a significant, global problem. While the devastation caused by disease is an issue for all wheat growing regions of the world the problem is confounded in those countries where low wheat yields and the general economic climate prohibit the use of fungicides. This is never more apparent than for resource poor, small scale farmers in Africa. In 1999 a new race of stem rust appeared in Uganda, overcoming the resistance present in 70% of wheat varieties. This new race, commonly known as Ug99 contributed to the global wheat price increases seen in 2007 and 2008, with the price of a loaf of bread in east Africa increasing by 70%. In 2000 a new, more aggressive race of stripe rust was detected in the US which was able to grow at higher temperatures. This race was found in Europe in 2001 and Western Australia in 2002, where previously the warmer climate was not conducive to stripe rust infection. This represented the fastest reported spread of a new pathogen race. It is therefore vital that sustainable wheat production systems are put in place. The development of high-yielding, disease resistant wheat varieties will go a long way to achieve this. In this project we undertake a genetic and biological characterisation of a number of sources of novel resistance to stem and stripe rust, which has proven effective against these two diseases in southern and eastern Africa. The genes responsible for the resistance will be genetically defined using DNA markers to locate the position of the genes and measure the contribution of each to the overall resistance. Biological studies will inform as to the mechanisms of resistance such gene confers, thereby informing wheat breeders which genes to accumulate into new wheat varieties to obtain additive effects. DNA markers will be developed for each resistance gene using the latest marker technologies. DNA markers provide tools by which wheat breeders can pyramid a number of resistance genes, allow for the development of superior wheat varieties in a much reduced time frame. To ensure that these DNA markers can be used by national wheat breeding programmes within Africa two marker platforms will be established within research and breeding institutes in South Africa and Kenya. The project therefore contains a large capacity building programme, providing physical infrastructure and trained personnel. A knowledge-technology transfer pipeline will be established from the UK into Africa, using RSA and Kenya as the entry points, which will function both during the lifetime of this grant and beyond.