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ICARDA
and CIMMYT Harnessing the Power of Partnership in Wheat Improvement |
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Breeding and Testing Resistant Wheats In Central Asia, yellow rust, tan spot, and common bunt are major foliar diseases of spring wheat, although septoria leaf blotch, leaf rust, and cereal cyst nematode also occur in some areas. Yellow rust and leaf rust are also very important in the Caucasian countries. As researchers develop new varieties resistant to these diseases, they test their progress through a step-by-step evaluation at different locations in the region.
In the second step, varieties identified as resistant are further screened for resistance to different diseases in heavily infected areas in different countries in CWANA, in collaboration with local scientists at three to five sites per country. Resistance to yellow rust, for example, is assessed in Algeria, Azerbaijan, Egypt, Eritrea, Ethiopia, Iran, Kazakhstan, Kyrgyzstan, Lebanon, Morocco, Syria, Tajikistan, Tunisia, Turkey, and Uzbekistan. Resistance to leaf rust is assessed in Azerbaijan, Egypt, Eritrea, Iraq, Lebanon, and Morocco. Resistance to septoria leaf blotch is assessed in Algeria, Iran, Iraq, Lebanon, Morocco, Syria, Tunisia, and Turkey. Material identified as resistant to one or more diseases is grouped into germplasm pools and incorporated in the breeding program to be developed into new lines or tested for yield performance in target environments. Artificially inoculated wheat varieties that are resistant to disease have also been shown to be resistant to natural infection at disease "hot spots" in different agroecological zones in CWANA, proving that the step-by-step approach works efficiently. Artificial inoculation makes it possible to evaluate a large number of accessions very quickly, and also allows researchers to evaluate interactions that occur between the seedlings and adult wheat plants and the pathogen. Artificial inoculation also saves time and effort because the resistance of the most promising experimental varieties is accurately evaluated before being dispersed to different locations to assess yield levels and adaptation to specific environments. Artificial inoculation is done using the range of fungal pathotypes of disease-causing organisms existing in the area where a particular variety will be tested.
An important feature of rust disease resistance research is that all of the countries in CWANA are part of a global network to improve resistance to many diseases in wheat and benefit from wider international efforts to develop durable resistance to the diseases. Durable resistance relies on combinations of genes, rather than single genes, to act as antidotes to rust pathogens. With durable resistance, plants can sustain a low level of infection but still yield well, and the evolution of new races of pathogens is delayed. |
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