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POSTERS: Population biology and genetics

Spread of the famine lineage of Phytophthora infestans into the African and Asian continents
Jean Ristaino - North Carolina State University. Amanda Saville- North Carolina State University

The FAM-1 clonal lineage of Phytophthora infestans caused late blight in the 1840s in the US and Europe. FAM-1 (HERB-1 mtDNA haplotype) was the only lineage detected in herbarium samples from the US and Europe collected from the 1840s through 1930. Spread of the lineage to other continents has been reported, but had not been extensively researched, and it was assumed that the US-1 lineage caused the first outbreaks on other continents. We examined 48 herbarium samples from the African and Asian continents collected between 1910 and 1991 and used 12 microsatellite (SSR) loci to identify FAM-1 and mtDNA sequencing to identify HERB-1. The famine lineage was detected in approximately 35% of the samples and was found in samples collected between 1910 and the 1950s. In Africa, the famine lineage was found in Uganda, Tanzania, Kenya, Zimbabwe, Cameroon, and Ethiopia, all of which were subject to European colonialism and/or occupation. In Asia, FAM-1 was found in the Philippines, India, and Malaysia, also countries subjected to European and/or US colonialism, and in Nepal. The US-1 lineage was not detected in any samples collected from Africa or Asia before the 1950s. The data from historic samples suggest that the famine lineage was spread during global colonization, most likely via potato tubers from Europe and/or the US, and was subsequently displaced by US-1 in the 1950s.