Mating type revulsion and dynamic genetic diversity of Phytophthora infestans during 2010–2021 in yunnan, China

Abstract Potato late blight caused by Phytophthora infestans is the most severe problem in the Yunnan Province. To understand the population dynamics of P. infestans in Yunnan during 2010–2020, 357 isolates were collected from Dali and Kunming, purified, and analyzed for the mating type, mitochondrial DNA (mtDNA) haplotype, metalaxyl resistance, pathotype, and simple sequence repeat (SSR) DNA fingerprints. The A1 mating type was dominant before 2012, but since 2012, the A2, A1A2 and self-fertile types became dominant and fewer A1 isolates were obtained over the years. Among the 357 isolates, only two were IIa mtDNA haplotypes and the rest were Ia mtDNA haplotypes. Pathogenicity assays using R1-R11 gene carried hosts revealed 67 pathotypes among all test isolates. SSR analysis identified 242 multi locus genotypes(MLGs), combined principal component analysis indicated that populations in 2010, 2011 and 2012 predominantly adopted asexual life cycles, but from 2013 to 2021, limited sexual reproduction likely occurred. UPGMA analysis indicated that five test isolates collected from Dali and Kunming from 2013 to 2015 but not in other years represented the EU_13_A2 lineage. Our results support the hypothesis that clonal reproduction, combined with host selection and limited sexual reproduction, underlies the dynamic genetic diversity of P. infestans in Yunnan.