Population structure of Phytophthora infestans in China – geographic clusters and presence of the EU genotype Blue_13

Abstract

The population structure of Phytophthora infestans in China was studied and three mitochondrial haplotypes (Ia, IIa, IIb) were observed. Genetic analysis with 10 highly informative SSR markers identified 68 different genotypes, including three dominant clonal lineages. In the Chinese P. infestans population, the genotypes were strongly clustered according to their geographic origin. One of dominant clonal lineages was genetically similar to Blue_13, a dominant clonal lineage found in Europe since 2004. This is the first report of Blue_13 outside Europe. Only one mating type (A1) was found in the northern and southeastern provinces, but in southern and northwestern China both mating types were observed. The mating type ratio and SSR allele frequencies indicate that in China the sexual cycle of P. infestans is rare. These results emphasize that the migration of asexual propagules and the generation of subclonal variation are the dominant driving factors of the population structure of P. infestans in China. They may also have implications for the role of monitoring P. infestans populations in potato late blight management strategies in China.

Severe outbreaks of late blight on potato and tomato in South India caused by recent changes in the Phytophthora infestans population

“…In this study, the P. infestans population infecting tomato and potato collected from different commercial fields in South India were A2 mating type, mitochondrial DNA haplotype Ia, resistant to metalaxyl and highly aggressive on both tomato and potato. This clonal lineage has a characteristic RG57 pattern and SSR loci matching with the multilocus genotype (MLG) 13_A2 lineage reported in European countries and China (Cooke et al ., ; Li et al ., ). A novel A2 mating type and metalaxyl‐resistant clonal lineage, termed 13_A2, was first reported from the Netherlands and Germany in 2004 and migrated to Great Britain in 2005 and displaced the other clonal lineages in less than 3 years (Cooke et al ., ).…”

Large subclonal variation in Phytophthora infestans populations associated with Ecuadorian potato landraces

“…The presence of more than two peaks in some of the SSR profiles supports the hypothesis that polyploidization or gene duplication followed by mutations caused the genetic diversity observed in the P. infestans population of Ecuador (Tooley & Therrien, ; Cooke et al ., ). The occurrence of more than two alleles at a specific locus has been reported before (Knapova & Gisi, ; Lees et al ., ; Chacón Acosta, ; Akino et al ., ; Oliva Pérez, ; Cooke et al ., ; Li et al ., ,b). The same mechanism seems to be active in P. andina also, where four alleles were observed (Fig.…”

The Irish potato famine pathogen Phytophthora infestans originated in central Mexico rather than the Andes

“…The commercial potato seed trade can explain much of the current global population structure of P. infestans; however, the early movements of P. infestans have not been fully reconstructed (1), and examination of the processes underlying the emergence of new, highly successful strains is ongoing (3,39). The diverse population in central Mexico may be the ultimate source for the appearance of new strains worldwide (3,40), although seed potatoes from Europe are behind recent migrations of virulent strains (41,42). Detailed genetic reconstruction of global migrations of P. infestans may be feasible using population genomic data.…”