Tuesday, March 30, 2010

Diseases and climate change

This year AfricaRice is starting one of the first efforts to look at the relationship between plant diseases and climate change. The project is funded by the GTZ (German Technical Cooperation), and is called “Mitigating the impact of climate change on rice disease resistance in East Africa.” It will work in Uganda, Rwanda and Tanzania, led by Dr. Yacouba Séré. According to the International Panel on Climate Change the Great Lakes region of Africa is expected to be especially vulnerable to climate change.

Even without climate change, there is much to be done in East Africa. In recent years, high temperatures and erratic rainfall in Uganda have contributed to an increase of diseases like rice blast, brown spot, grain rot and bacterial blight. In Tanzania, there are few rice varieties which are resistant to disease. Rice blast and sheath rot have caused 20% loss of the rice crop in Rwanda. Rice diseases often adapt quickly to their hosts, so that new varieties may lose their disease resistance within a few years.

A first step will be to learn more about the diversity of pathogens and their relationship to rice. The project will study the interactions between diseases and rice and will identify genes that will help breeders to develop varieties with more durable resistance. Effective genes can be added to popular varieties using marker assisted selection (MAS).

The team will also study farmers’ knowledge of disease and climate change, to build on indigenous knowledge. The project will link with advanced institutions, especially German universities.

Scientists will develop a model to predict what will happen to the pathogens and to the rice varieties under different climate scenarios. A variety which is resistant now may not be as climate changes. A minor disease may become a major stress as climate change and vice versa.

Two of the important rice diseases in the region are rice blast and bacterial blight. Both are greatly affected by climate, especially temperature and humidity. As the temperature increases, so may the incidence of rice diseases.

At the end of this three year project AfricaRice will have more information on the current situation of the interaction between rice varieties and rice pathogens (especially for blast and bacterial blight), on how rice diseases will respond to climate change, and on the genes that will be needed in the future to protect rice.