A pandemic clonal lineage of the wheat blast fungus

Wheat blast, caused by Magnaporthe oryzae (Syn. Pyricularia oryzae), was recently reported in Africa for the first time. To determine the relationship between African wheat blast isolates from Zambia with other populations from South America and Bangladesh, we analyzed the genotyping data recently reported by Tembo et al. (2021). The dataset consists of 84 single nucleotide polymorphisms (SNPs) obtained by multiplex amplicon sequencing from 186 isolates amended with data from 67 isolates mined from publicly available genome sequences. We observed that the Zambian isolates (N=13, 2018-2020) are identical for the 84 SNPs to isolates from Bangladesh (N=81, 2016-2020) and one genotype from South America (Bolivia, N=1, 2012). We conclude that the "B71" clonal lineage that emerged in South East Asia in 2016 and traces its origins to South America is now established in Zambia. Further analyses using whole genome sequences are needed to validate this conclusion. These findings call for urgent action, including a mitigation plan to prevent further spread.