Developing Strategies for Identifying Sources of Resistance for the Intractable Wheat Blast Disease

Wheat blast, caused by the Triticum pathotype of Magnaporthe oryzae (MoT), is an emerging disease considered to be a limiting factor to wheat production and regarded as very difficult to control. Wheat blast has spread within South America and it occurred for the first time in Bangladesh in 2016. The urgent threat of wheat blast demands identification of new sources of resistance, understanding of currently deployed resistance, and elucidation of important ecological aspects. Current research, performed in the U.S. and Bolivia are aimed to (i) identify novel sources of blast resistance, (ii) understand the background effect of 2NS-based resistance and (ii) elucidate basic ecological aspects of the wheat blast pathosystem. Spring, winter, landraces, and wild-type wheat relatives are being tested. Cultivars showing good levels of resistance are being screened for the presence of the 2NS segment; selected candidates will be chosen to develop population(s) for QTL mapping. A large panel of phenotypic and genotypic data will later be used to identify novel regions associated with wheat blast resistance through a genome-wide association study. Although head infection is the most visible symptom in the field, leaf infection could also occur. The genetic variability of different MoT isolates collected from leaves and heads in the field will be studied. Identification of novel sources for blast resistance, a better understanding of 2NS-based resistance, and elucidation of key ecological aspects of the wheat blast pathosystem will potentially contribute to develop better strategies for wheat blast management.