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Phenotypic and Genotypic diversity in Phytophthora infestans Isolates in Korea

Md Aktaruzzaman: Gangneung-Wonju National University

<div>The oomycete, <em>Phytophthora infestans</em> (Mont.) de Bary causes late blight disease in potato (<em>Solanum tuberosum</em> L.) worldwide including South Korea. In the present study, we analyzed phenotypic characteristics such as mating type, metalaxyl resistance, fitness composites and physiological race of <em>P. infestans</em> isolates in Korea. The DNA-based markers called SSRs were also used for analyzing the genetic diversity among the isolates. For phenotypic characterization, a total of 301 isolates were purified from different locations of Korea in 2013-2016. All the isolates were identified as A1 mating type. Frequencies of isolates resistant (4.7%, 4.9%, 9.7 % and 8.5%), moderately resistant (75.3%, 80.4%, 77.3 % and 75.8%) and sensitive (20.0%, 14.7%, 16.6% and 15.7%) to matalaxyl were found in 2013 to 2016, respectively. Fitness components and composite fitness index of metalaxyl resistant isolates were higher compared to metalaxyl sensitive isolates. Total number of physiological race of <em>P. infestans</em> was detected 17, 25, 22 and 23 in 2013 to 2016, respectively. Among them, the races R0., R0., R0. and R0. were dominant and showed virulence to potato, except R8 and R9. For genetic diversity, we analyzed 172 <em>P. infestans </em>isolates from 2009-2016. In our study, 45 multi-locus genotypes (MLGs), which were classified into four genotypes KR-1, KR-2, RU-1 and US-11. KR-1 and KR-2, where KR-2 was a new genotype.</div>