Whole-genome analyses of 286 Magnaporthe oryzae genomes suggest that an independent introduction of a global pandemic lineage is at the origin of the Zambia wheat blast outbreak

The emergence of agricultural pests is a severe threat to global food security. The recent wheat blast outbreak in Bangladesh had devastating consequences for the country. More recently, a wheat blast outbreak in Zambia was assigned to the same tight group of genotypes originally introduced from South America into Bangladesh. Here, I analyzed publicly available whole-genome sequencing datasets shared by the OpenWheatBlast initiative. The aim is to contrast the Zambian outbreak strains with genome-wide differentiation of Magnaporte oryzae infecting different hosts. The genome-wide SNP analyses show that the Zambian outbreak strains are indeed highly similar to the strains responsible for the outbreak in Bangladesh as recently reported. The genomic data suggest that the Zambian outbreak may have originated from South America rather than a secondary introduction from the South Asian gene pool. The genome analyses confirm that wheat blast has emerged in recent years as a pandemic lineage across three continents. I provide the analyses as an open science contribution to the OpenWheatBlast initiative.