Identification of genetic rust resistance in bread wheat

Executive Summary

Sources of wheat rust resistance were sought in the Southern Cone where there are two epidemiological zones separated by the Andes Mountains. Leaf rust (Puccinia triticina) and striated rust (P. striiformis) are the most important diseases. The populations of both pathogens are dynamic with frequent changes in virulence that reduce the duration of resistance of commercial cultivars. Adult plant resistance, determined by additive genes, is used to stabilize the effect of the pathogens and achieve long-lasting resistance. Germplasm with low infection coefficient and stable resistance sources were selected and distributed to breeding programs.  Resistance of commercial cultivars results from the combination of genes of greater effect but is not durable and is associated with changes in virulence of pathogens. Reaction to rust of commercial cultivars and isogenic differential lines was evaluated and in several cases resistance was maintained. Population changes of P. triticin were evaluated and races that are virulent on local cultivars were identified. Changes in the prevalence of races and the emergence of new races confirm that the population of the pathogen is very dynamic. Representative isolates of this variability have been preserved. An avirulent race over most commercial cultivars predominates in the region although cultivation of susceptible wheat may increase infections. 

The technological solution

The preliminary technological solution has been the determination of genetic resistance factors to wheat rust. This information, in addition to the knowledge about population dynamics and variability of pathogen virulence, also produced by the project, will serve to obtain the final technological solution which is the generation and release of commercial varieties resistant to rust. The production sector of reference is that of wheat production in the Southern Cone where more than 9 million ha are planted. 

Results

Beneficiaries

The immediate beneficiaries are the region's breeding agencies and scientists dedicated to reducing the negative effects of wheat rust on productivity and farmers' incomes. In the long term, after the release of commercial varieties with long-lasting resistance, the final beneficiaries will be the producers who will reduce production risks by having wheat varieties that are less susceptible to two serious plant diseases. 

Sustainable Development Goals

Main donors