Field Nurseries in East Africa: Promoting International Collaborations and Training

Wheat disease epidemics have significant impacts on food security, especially in areas where crops are grown under marginal conditions. Stem rust (Sr) of wheat and barley, caused by the fungus Puccinia graminis f. sp. tritici, is an example of a disease that has historically threaten small grain production worldwide. However, use of wheat varieties carrying Sr resistance genes prevented major epidemics from occurring over the past four decades. In 1999, a strain of the Sr fungus, with virulence for resistance genes present in over 80% of the wheat varieties grown worldwide, was identified from rust samples collected in Uganda in 1998. This strain and its subsequent variants, colloquially known as Ug99, have now spread across East Africa to South Africa and as far north as Egypt, Yemen and Iran. To address the dire situation, an international group of scientists, led by Nobel Peace Prize laureate and “father of the Green Revolution”, Dr. Norman Borlaug, established the International Stem Rust Screening Nurseries in Kenya and Ethiopia. This collaborative group focused on identifying effective sources of resistance to Ug99 (and its variants) that could be used to reduce Sr epidemics. Since its inception in 2009, researchers from national and international research centers, universities, government agencies and the private sector have screened wheat and barley lines from breeding programs and seed banks under Sr epidemics. To date, the international effort has evaluated over 467,000 wheat and barley lines and have successfully identified 40 Sr genes that are effective to one or more of the Ug99 strains. Based on this effort, 12 wheat varieties have been developed and are being deployed in “imminent threat” areas, and many more are in development. Additionally, the international nursery located in Kenya has been used as a classroom to train over 200 junior scientists during the annual “Standardization of stem rust note taking and evaluation of germplasm” courses. The international screening nurseries are a center of scientific discoveries, melting pots of ideas, birthplaces of new wheat varieties, collaboration outlet and classroom for junior and senior scientists alike. The results from the international nurseries have demonstrated that greater advances can occur when scientific communities, across disciplines and institutions work as one cohesive unit instead of a group of individuals.