Characterization of some Asian isolates of Phytophthora infestans

Abstract

A total of 401 isolates of Phytophthora infestans were collected from eight Asian regions (Korea, India, Taiwan, Indonesia, Thailand, Nepal, China and Japan) between 1992 and 2000 -318 from potato and 83 from tomato. The isolates were analysed for mating type, metalaxyl resistance, RG57 fingerprinting, mitochondrial DNA (mtDNA) haplotype and the polymorphism of three allozyme loci, i.e. glucose-6-phosphate isomerase ( Gpi ), peptidase ( Pep ) and malic enzyme ( Me ). The isolates were multilocus-genotyped based on RFLP (RG57) fingerprint, dilocus allozyme genotype, mtDNA haplotype and mating type. Twenty multilocus genotypes were identified among 125 isolates. Of these genotypes, 14 had not been previously reported. Some of the multilocus genotypes were common to isolates from several geographical regions, suggesting migration. The metalaxyl-resistant isolates belonged to the multilocus genotypes JP-1, JP-2, and JP-3. Multilocus genotypes coexisting in a single field were found in following regions: Thailand (1994), central China (1996), Nepal (1997 and Japan (1998 and2000). The possible origins of certain genotypes are discussed, including the possibility of sexual recombination within the P. infestans populations in Nepal and perhaps Thailand.

Use of microsatellite marker Pi26 for rapid discrimination of five Japanese genotypes of Phytophthora infestans

“…Phytophthora infestans, the pathogen of late blight in potatoes and tomatoes, has many different genotypes worldwide (Forbes et al 1998). In Japan, five genotypes of P. infestans, defined as RG57 fingerprint types, have been reported in recent years (Gotoh et al 2005). Isolates of genotypes US-1, JP-2, JP-3, and JP-4 are A1 mating types, and JP-1 is an A2 mating type.…”

“…PCR reactions were done with three replications as described by Cooke (2008). PCR samples were loaded into the DNA sequencer (model CEQ 8000 Genetic Analysis System; Beckman Gotoh et al (2005) b Identified in Gotoh et al (2007) c American Type Culture Collections (ATCC208835) d Size of the PCR products generated by Pi26F and Pi26R primers Coulter, Tokyo, Japan) and run according to the manufacturer's instructions. Peak size data were analyzed using Fragment Analysis Software (Beckman Coulter) for estimating allele sizes.…”

Identification and mapping of quantitative resistance to late blight (Phytophthora infestans) in Solanum habrochaites LA1777

“…Late blight causes serious yield and economic losses especially under favorable conditions for the pathogen (wet and cool temperatures) both in the open field as well as in non-heated greenhouses. The responsible pathogen is heterothallic and forms oospores with A1 and A2 mating types and has been found in different areas of the world (Gotoh et al 2005). The co-existence of mating types and the sexual reproduction increase the chance of developing resistance to fungicides such as metalaxyl (Goodwin et al 1998;Gotoh et al 2005).…”

“…The responsible pathogen is heterothallic and forms oospores with A1 and A2 mating types and has been found in different areas of the world (Gotoh et al 2005). The co-existence of mating types and the sexual reproduction increase the chance of developing resistance to fungicides such as metalaxyl (Goodwin et al 1998;Gotoh et al 2005). In addition, the spread of the disease may be also initiated from spores present in the soil (Widmark et al 2007).…”

“…In addition, the spread of the disease may be also initiated from spores present in the soil (Widmark et al 2007). The genetic diversity, rapid evolution and the broader range of virulence factors have made this pathogen more and more aggressive (Drenth et al 1995;Gotoh et al 2005). Tomato plants can be completely destroyed in a few weeks despite the use of chemicals to control the infections (Jones et al 1991).…”