The International Maize and Wheat Improvement Center’s screening nurseries in Bolivia and Bangladesh evaluated
Wheat blast caused by the fungus Magnaporthe oryzae pathotype Triticum (MoT) is an emerging threat to wheat production. To identify genomic regions associated with blast resistance against MoT isolates in Bolivia and Bangladesh, scientists performed a large genome-wide association mapping study using 8607 observations on 1106 lines from the International Maize and Wheat Improvement Centre’s International Bread Wheat Screening Nurseries (IBWSNs) and Semi-Arid Wheat Screening Nurseries (SAWSNs).
They were able to identify 36 significant markers on chromosomes 2AS, 3BL, 4AL and 7BL with consistent effects across panels or site-years, including 20 markers that were significant in all the 49 datasets and tagged the 2NS translocation from Aegilops ventricosa. This study reinforces the effectiveness of the 2NS translocation for blast resistance and emphasizes the urgent need to identify novel non-2NS sources of blast resistance.
While wheat imported from Brazil was considered to be the likely source of the disease, a combination of warm and humid conditions during the heading stage triggered the epidemic, that is generally favored by high temperatures between 25 and 30 °C and an increased wetting period. The blast outbreak in Bangladesh escalated concerns of spread into the neighboring South Asian regions with similar environmental conditions5, and about seven million hectares in India, Pakistan and Bangladesh were estimated to be vulnerable to the disease.
Management of wheat blast using fungicides is possible, but has been reported to be elusive, because of the inefficiency of fungicides in offering complete control under high disease pressure, the resistance in MoT populations to some classes of fungicides, and the high cost of the fungicides that cannot be afforded by resource-poor farmers.
