Global wheat crops threatened by a fungus

Wheat crops worldwide are being threatened by a strain of stem rust. The fungus originated in Africa and is now migrating into wheat growing regions on other continents.

Nature reports that experts are meeting this week in Mexico's Ciudad Obregón to discuss the threat. Stem rust is a fungus called Puccinia graminis. It infects and destroys wheat. Wheat is the most important wheat disease and it is devastating because it can destroy the entire wheat plant. There are many wheat strains that have genes that are resistant to wheat rust, but this particular strain, called Ug99, that was identified in Uganda and classified in 1999, seems to be able overcome most of them. Thanks to the theory of evolution, we know that organisms evolve, and diseases caused by organisms are no exception to that rule. It is known that wheat rust comes from Africa, and that this is also where the new strains come from. Hence, the fact that Ug99 comes from Africa, is hardly a surprise. Unfortunately, scientists didn't see this threat coming. Until the mid-1980s, CIMMYT, the International Maize and Wheat Improvement Centre, based in El Batan, Mexico, had a research station in Kenya to keep an eye on things. However, during the mid 1980s, there was plenty of food produced and interest for the program waned. The station was closed because no one was interested in funding it. As a result, Ug99 came about without anyone noticing, and now it is here. In other words, Ug99 is largely the consequence of depriving agricultural research of money. We must build a defense against this fungus, but that takes time. When the world was warned against Ug99 in 1999, no one was interested. It took someone of the calibre of Norman Borlaug(*) before they started to listen. It is hoped that weather conditions will temporarily limit the spread, such as the extreme drought last year in Iran, which prevented the fungus from spreading. That gives us some time to develop a defense, but time is limited, since the disease will spread sooner, rather than later. One of the strategies being used is to create wheat strains that don't have genes with major resistance against rust, but that have several genes with minor resistance that combine to create major resistance. It is hoped that this will make it more difficult for stem rust to overcome the resistance. The reason for this is that natural evolution can relatively easily adapt to single genes, but has a far harder time to adapt to multiple genes. ---- Norman Borlaug is considered the father of the "green revolution." He has won the 1970 Nobel Peace Prize for his work on improving the global food supply. It is said that his work has saved the lives of hundreds of millions of people, possibly as much as a billion people. He is now the chair of the Borlaug Global Rust Initiative.