Phenotypic and Genotypic Characterization of Phytophthora infestans Isolates from China

Abstract

A total of 288 (202 from potato and 86 from tomato) isolates of Phytophthora infestans were collected from 1998 to 2007 in China. The isolates were characterized based on mating type, in vitro metalaxyl sensitivity, virulence on potato differentials, allozymes of glucose-6-phosphate isomerase (Gpi), peptidase (Pep), and mitochondrial DNA (mtDNA) haplotype and examined by DNA-based simple sequence repeat (SSR) and random amplified polymorphic DNA (RAPD) fingerprinting. The majority (283 of 288) of the isolates were of the A1 mating type, the other three were the A2 mating type and two were the A1A2 mating type. Resistance to metalaxyl was frequently observed, with 248 (86.1%) resistant, 21 (7.3%) intermediate and 19 (6.6%) sensitive isolates identified. Virulence was assessed for 125 isolates on a set of 11 potato differentials and 61 races were detected. Most isolates were virulent on the differential genotype with gene R3, and all known virulence genes were found, with race 3.4.7.11 being the most common. This pattern did not appear to be associated with geographic origin, sample type, mating type or metalaxyl sensitivity. The dominant banding patterns for Gpi were 100 ⁄ 100 ⁄ 111 (176 isolates) and 100 ⁄ 100 (109 isolates), but genotypes 86 ⁄ 100 and 100 ⁄ 111 were also identified. All isolates tested were homozygous (100 ⁄ 100) at the Pep locus. The majority (205 of 288) of isolates tested was of mtDNA haplotype IIb, 76 were haplotype IIa and seven were the rare Ib haplotype. The genetic diversity of 60 representative isolates from China was assayed by two types of molecular markers, RAPD and SSR. A high level of polymorphism was found. The results demonstrated the diverse phenotypic and genotypic structure of the current populations of P. infestans in China.

Phytophthora infestans Field Isolates from Gansu Province, China are Genetically Highly Diverse and Show a High Frequency of Self Fertility

“…Li et al. () used 14 SSR markers to detect the diversity among 60 P. infestans isolates from China, but genotypes of these isolates were not documented and reference isolates were not reported in that study. Guo et al.…”

“…; Li et al. ; Zhu et al. ), few studies have genotyped P. infestans populations with SSR markers, or investigated the possibility of sexual reproduction in the field in North Central China.…”

“…Subsequent reports have documented the phenotypes of P. infestans isolates from different locations in China with respect to mating type and fungicide resistance (in particular resistance to metalaxyl) (Bi et al 2006;Jin et al 2006;Ryu et al 2003;Wang et al 2003;Zhao et al 2007). Although several studies have examined the genetic structure of the Chinese P. infestans populations (Akino et al 2004;Gotoh et al 2005;Guo et al 2010a;Li et al 2009;Zhu et al 2006), few studies have genotyped P. infestans populations with SSR markers, or investigated the possibility of sexual reproduction in the field in North Central China.…”

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

“…However, lower frequencies were observed in other studies, e.g. Nepal 30 out of 251, Estonia 86/432, Finland 66/269, Norway 38/105, Nordic countries (Denmark, Finland, Norway and Sweden) 31/177 and China 61/125 races (Hermansen et al ., ; Ghimire et al ., ; Lehtinen et al ., ; Li et al ., ; Runno‐Paurson et al ., ). It should be noted that in Denmark, Estonia, Finland, Norway and Sweden sexual populations are dominant, and the populations seems to be clonal in China and Nepal (although both mating types can be found), whereas the population in Ecuador is clonal.…”

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

“…In a previous study (Zhang et al ., ), the frequency of the A2 mating type was much higher in northern China (Inner Mongolia and Hebei) than in southern China (Sichuan and Yunnan). However, in this study, no A2 isolates were found in northern China, corroborating the reported decline of the A2 mating type in China (Li et al ., ) and the absence of the A2 mating type in northern China (Guo et al ., ). Although the presence of both mating types was observed by Zhang et al .…”