Genotypic and phenotypic characterization of Phytophthora infestans in South Korea during 2009–2016 reveals clonal reproduction and absence of EU_13_A2 genotype

Abstract

In order to better understand the Phytophthora infestans population structure in South Korea, 172 isolates were collected between 2009 and 2016 from four major potato cultivation areas. Fungicide (metalaxyl and dimethomorph) response, mating type, and microsatellite (SSR) genetic fingerprints were analysed to characterize these isolates. Ten isolates collected in Gyeongnam Province, which specializes in protected winter cultivation in polytunnels, were A2 mating type. All other isolates were A1 mating type. Overall, 42% of the isolates were resistant to metalaxyl, and 43% were sensitive. All isolates were sensitive to dimethomorph. From the SSR fingerprints, 45 distinct genotypes were identified, which could be clustered into four clonal lineages: KR_1_A1, KR_2_A2, SIB‐1, and US‐11. KR_1_A1 was the predominant P. infestans genotype in South Korea. KR_2_A2 was only found in Gyeongnam Province; all isolates were A2 mating type and resistant to metalaxyl. SIB‐1 was dominant until 2013 but its frequency has gradually decreased in more recent years. US‐11 was first found in 2014, after which its frequency has increased to become codominant with KR_1_A1. The calculated standardized index of association (IA) suggests that the South Korean P. infestans population is undergoing clonal reproduction. When compared with populations of P. infestans from the Netherlands, it has less genetic diversity and the dominant Netherlands P. infestans genotype, EU_13_A2 (Blue_13), was not found in South Korea. Such monitoring of the pathogen population contributes to a more efficient integrated pest management‐based control strategy for potato late blight control in South Korea.

The dynamics of Phytophthora infestans populations in the major potato‐growing regions of Asia – A review

“…Thus, in South Korea, as in Japan, the A2 JP‐1 genotype was displaced by the A1 JP‐2 in the early 2000s. A recent study by Choi et al (2020) shows continuing dominance of the population by A1 genotypes. They investigated the South Korean P .…”

“…infestans population using SSR markers to genotype 172 isolates collected between 2009 and 2016, and identified four clonal lineages, KR_1_A1, KR_2_A2, SIB‐1, and the A1 US‐11. The KR_1_A1 genotype identified by Choi et al (2020) could possibly be the same as KR‐1 designated by Zhang et al (2006), but there are insufficient genotypic markers common to the two studies to determine this. The A2 genotype KR‐1 of Gotoh et al (2005) could be related to KR_2_A2, which Choi et al (2020) consider to be a minor variant of JP‐1.…”

“…Thus, in South Korea, as in Japan, the A2 JP-1 genotype was displaced by the A1 JP-2 in the early 2000s. A recent study by Choi et al (2020) shows continuing dominance of the population by A1 genotypes. They investigated the South Korean P. infestans population using SSR markers to genotype 172 isolates collected between 2009 and 2016, and identified four clonal lineages, KR_1_A1, KR_2_A2, SIB-1, and the A1 US-11.…”

“…The A2 genotype KR-1 of Gotoh et al (2005) could be related to KR_2_A2, which Choi et al (2020) consider to be a minor variant of JP-1. US-11 was first found in 2014 and its frequency has increased since then; it was codominant with KR_1_A1 in 2014-2016 (Choi et al, 2020).…”

Population structure of Phytophthora infestans in Turkey reveals expansion and spread of dominant clonal lineages and virulence

“…These results were found to be compatible with many studies worldwide (Gisi & Cohen, 1996; Harbaoui et al, 2014). In contrast, high amounts of sensitive isolates in the population have been reported in Korea (Choi et al, 2020), Poland (Janiszewska et al, 2020), and the USA (Saville et al, 2015). In our study, the number of individuals extremely resistant to mefenoxam was high in all provinces except Afyon and Bursa.…”