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Phytophthora nicotianae and Pythium helicoides are important water-borne oomycete pathogens of irrigated ornamentals particularly ebb-and-flow irrigated kalanchoe in Japan. We developed novel PCR-based sequence characterized amplified region markers and assays for rapid identification and species-specific detection of both pathogens in separate PCR reactions or simultaneously in a duplex PCR.

Pythium intermedium is known to play an important role in the carbon cycling of cool-temperate forest soils. In this study, a fast, precise and effective real-time PCR technique for estimating the population densities of P. intermedium from soils was developed using species-specific primers. Specificity was confirmed both with conventional PCR and real-time PCR. The detection limit (sensitivity) was determined and amplification standard curves were generated using SYBR Green II fluorescent dye. A rapid and accurate assay for quantification of P. intermedium in Takayama forest soils of Japan was developed using a combination of a new DNA extraction method and PCR primers were developed for real-time PCR. And the distribution of P. intermedium in forest soil was investigated with both soil plating method and the developed real-time PCR technique. This new technique will be a useful tool and can be applied to practical use for studying the role of Pythium species in forest and agricultural ecosystems., (Copyright © 2009 Elsevier GmbH. All rights reserved.)

A strategy combining dual-suppression PCR and thermal asymmetric interlaced PCR was used to determine sequences flanking microsatellite regions in Pythium helicoides. The primer pairs were designed to amplify loci containing (AC)n, (GA)n, (AGC)n, (CAC)n(CAA)n, (TCA)n and (CTTT)n repeats from the P. helicoides nuclear genome. The PCR products of each primer pair, amplified from three representative isolates collected from different hosts and locations, were cloned and sequenced. Different degrees of polymorphism were detected among these microsatellite markers. The numbers of alleles were 6, 2, 4, 11, 4 and 4 in YL-AC, YL-AGC, YL-CAA, YL-CTTT, YL-GA and YL-TCA, respectively. Allele analysis of 30 P. helicoides isolates showed length polymorphisms in all loci, except for YL-AC, using capillary electrophoresis. Thus, we have developed a simple method for designing PCR primers to amplify microsatellite markers from P. helicoides.

BACKGROUND: Phytophthora spp. represent a pivotal genus of plant pathogens with a global distribution, exerting significant deleterious effects on food safety and forestry ecosystems. Numerous pathogenic and invasive Phytophthora species, introduced through imported fruits, have been frequently detected at Chinese ports. With the rise in global trade activities, the plant quarantine of imported fruits is becoming increasingly important but challenging. Fast, simple, and labor‐saving techniques are necessary and anticipated. RESUITS: A polymerase chain reaction restriction fragment length polymorphism capillary electrophoresis (PCR‐RFLP‐CE) technology‐based quarantine approach was developed for 16 Phytophthora species associated with the imported fruits in China. The Ypt1 gene, exhibiting abundant interspecific variations, was selected as the marker gene for PCR. The restriction endonuclease AluI was proven to be capable and compatible in simultaneously separating different Phytophthora species during CE. By combining with a fast and efficient DNA extraction kit, the developed PCR‐RFLP‐CE technique was successfully applied to identify Phytophthora species in artificially infested fruits. CONCLUSION: We provide a quick, practical, and high‐throughput detection approach for hazardous and invasive Phytophthora species associated with imported fruits in China. This strategy can give good convenience and technological support for carrying out massive quarantine activities at Chinese ports. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Phytophthora cactorum, P. cinnamomi and P. lateralis were reported to be pathogenic on kiwifruit trees in the main planting areas of China. We attempted to simultaneously detect the three pathogens using a multiplex polymerase chain reaction (PCR) and to survey their occurrence in the main production areas. Because of the need to combine different primer pairs for the multiplex PCR and the low specificity of published specific primers for P. cactorum, P. cinnamomi and P. lateralis, new species-specific primers for the three species were designed based on the ras-related protein gene, Ypt1. The specificity of the designed primers was demonstrated using 52 isolates, including 44 Phytophthora species, three Pythium species, and three other soil-borne pathogens. A multiplex PCR method for the simultaneous detection of P. cactorum, P. cinnamomi and P. lateralis was established, and the three pathogens were detected in artificially and naturally infested soils, indicating that these markers can be used in the diagnosis of kiwifruit Phytophthora diseases. In a survey of these pathogens in the main kiwifruit planting areas of China, 99 soil samples were collected at different locations and in different seasons and subjected to the new method, and the distribution of the three pathogens in the main kiwifruit planting areas of China was determined. [ABSTRACT FROM AUTHOR]

The purpose of this study was to clarify the genetic diversity of Phytopythium helicoides and to understand the transmission mode of the pathogen in Japan. In total, 232 P. helicoides isolates were collected from various host plants and geographic origins, including farms and natural environments. We developed 6 novel microsatellite markers for use in the study and found 90 alleles among the 6 markers in the 232 isolates. The analysis of molecular variance suggested that P. helicoides has high variance within individuals and low fixation indices between populations. A phylogenetic analysis revealed that isolates collected from the same hosts and/or geographic origins were often grouped together. For example, several isolates from natural environments were grouped with isolates from nearby agricultural areas. On the other hand, 2 geographically distant populations collected from the same host plant had similar genotypes. Our results suggested that migration of the pathogen could be facilitated naturally via drainage systems or by human activity in the transport of agricultural materials. [ABSTRACT FROM AUTHOR]

The article discusses the etiological and ecological studies that used molecular techniques to develop methods for the identification and controlling of oomycete plant pathogens pythium and phytophthora. It states the polymerase chain reaction (PCR) technique to monitor water-borne plant pathogens. It mentions the loop-mediated isothermal amplification (LAM) for efficient DNA amplification at reaction temperature.

Root rot of poinsettia, caused by Pythium helicoides at high temperatures in hydroponic cultures, has become a serious problem in many parts of the world. We have developed a species-specific, loop-mediated isothermal amplification ( LAMP) assay for the rapid diagnosis of this pathogen. The primers were designed using the ribosomal DNA internal transcribed spacer sequence. Primer specificity was established using 40 Pythium species including P. helicoides, 11 Phytophthora species, and eight other soil-borne pathogens. A sensitivity test was carried out using genomic DNA extracted from P. helicoides, and the detection limit was c. 100 fg which is comparable to that of the polymerase chain reaction ( PCR). In addition, we tested the ease of pathogen detection in poinsettia roots. The LAMP results were consistent with those from the conventional plating method and showed more sensitivity than the PCR results. Consequently, the LAMP method developed in this study is effective for the rapid and easy detection of P. helicoides. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop a multiplex PCR detection method for the high-temperature-growing pathogens Pythium aphanidermatum, P. helicoides and P. myriotylum. Species-specific primer pairs were designed that targeted the rDNA ITS regions. The multiplex PCR was constructed with a universal primer pair for eukaryotes directed at the 18S rDNA as a positive control, in addition to the three species-specific primer pairs. When the multiplex PCR was applied to naturally infested soils, the expected species were reliably identified, suggesting that the method is suitable for the detection of the three Pythium pathogens in environmental samples. [ABSTRACT FROM AUTHOR]

A strategy combining dual-suppression PCR and thermal asymmetric interlaced PCR was used to determine sequences flanking microsatellite regions in Pythium helicoides. The primer pairs were designed to amplify loci containing (AC)n, (GA)n, (AGC)n, (CAC)n(CAA)n, (TCA)n and (CTTT)n repeats from the P. helicoides nuclear genome. The PCR products of each primer pair, amplified from three representative isolates collected from different hosts and locations, were cloned and sequenced. Different degrees of polymorphism were detected among these microsatellite markers. The numbers of alleles were 6, 2, 4, 11, 4 and 4 in YL-AC, YL-AGC, YL-CAA, YL-CTTT, YL-GA and YL-TCA, respectively. Allele analysis of 30 P. helicoides isolates showed length polymorphisms in all loci, except for YL-AC, using capillary electrophoresis. Thus, we have developed a simple method for designing PCR primers to amplify microsatellite markers from P. helicoides. [ABSTRACT FROM AUTHOR]

Abstract: Heterogeneity of the rDNA ITS region in Pythium helicoides and the phylogenetic relationship between P. helicoides and closely related species were investigated. In PCR-RFLP analysis of the rDNA ITS region of six P. helicoides isolates investigated, including the type culture, intraspecific variation was found at the HhaI site. The total length of fragments was longer than before cutting, indicating sequence heterogeneity within isolates. Digestion of the cloned rDNA ITS region derived from seven isolates with HhaI revealed polymorphisms among and within single zoospore isolates, and variability of the region was also present among the clones derived from the same isolate. To test whether the rDNA ITS region of closely related species and other regions in the genome of P. helicoides are also variable, the rDNA ITS region of P. ultimum and the cytochrome oxydase II (cox II) gene encoded in mitochondria were sequenced. P. ultimum had little variation in the rDNA ITS region. The cox II gene sequences of both species revealed only a low intraspecific variability and no intra-isolate variation. In the phylogenic tree based on the rDNA ITS sequences, all clones of P. helicoides formed one large clade that was distinct from the clades comprising morphologically similar species, such as P. oedochilum and P. ostracodes, and was closely related to P. chamaehyphon rather than the other species. [Copyright &y& Elsevier]

The polymerase chain reaction (PCR) is a rapid, precise method for detecting and identifying pathogenic bacteria. In addition to the published primers for identification of Agrobacterium tumefaciens up to species level, two sets of primers were designed to identify the nopaline and octopine types of Agrobacterium tumefaciens. The RBF-RBR primer set designed based on the nopaline type T-DNA right border detected the nopaline type A208 and R225f strains, and the ocsF-ocsR primer set derived from the ocs gene of the octopine type A. tumefaciens detected the octopine type A348 strain. After polymerase Chain reaction (PCR) amplification by the RBF-RBR primers, the A208 and R225f strains could be differentiated from each other by restriction fragment length polymorphism digestion using the restriction enzymes DraI and XbaI. Multiple colonies can be screened at one time in a single PCR tube with satisfactory efficiency, thereby allowing rapid detection of pathogenic A. tumefaciens. Following a rough screening by classical biovar medium and α-methyl-d-glucoside medium, the developed PCR system was introduced to identify isolates collected from soil and crown gall samples. Of 42 isolates determined to be A. tumefaciens, 7 were found to be octopine type; all the rest were R225f type. [ABSTRACT FROM AUTHOR]

A polymerase chain reaction method to detect soil-borne plant pathogens such as Pythium ultimum, Plasmodiophora brassicae, and Verticillium dahliae in soil was developed and used with a range of soil textures. DNA extraction was based on lyses with alkali buffer (pH 9.0) containing sodium dodecyl sulfate, extraction with benzyl chloride, and collection by ethanol precipitation. Four modified protocols – purification of extracted DNA from soil, independent addition of glass beads or skim milk to the extraction buffer, and addition of bovine serum albumin (BSA) to the PCR reaction mixture – were evaluated to enhance the sensitivity of detection. The effectiveness varied for three tested pathogens, but none of the four protocols negatively affected PCR detection. DNA purification was essential for detecting the three tested pathogens. Physical disruption with glass beads and the addition of BSA to the PCR reaction mixture were necessary for detecting V. dahliae, and the addition of skim milk was needed for Pl. brassicae. Additions of BSA and skim milk enhanced the detection of P. ultimum. The developed protocol seems applicable to the range of soil textures that are naturally inhabited by these three pathogens. By integrating multiple protocols to enhance sensitivity, PCR can be used to detect various soil microorganisms. [ABSTRACT FROM AUTHOR]

Abstract: PCR–RFLP based on the translation elongation factor 1α (TEF) gene was developed to identify Fusarium fujikuroi in the Fusarium (Gibberella) fujikuroi species complex. Ninety-three strains, most of which were obtained from various sources in Japan, were identified as F. fujikuroi and their capability to produce fumonisin was investigated using an in vitro assay. Fumonisin production was detected in 50 strains isolated from maize, strawberry, wheat, and rice, whereas it was undetectable in 43 strains derived from rice seeds and rice seedlings carrying the bakanae disease, and from unknown sources. A single nucleotide polymorphism in the TEF gene (T618G) correlated with the ability to synthesize fumonisin. [Copyright &y& Elsevier]

We aimed to simultaneously detect two pathogens causing strawberry diseases, Phytophthora nicotianae and P cactorum, by multiplex poly- merase chain reaction (PCR), and to survey their occurrence in the main strawberry production areas of Japan. Due to the need to combine different primer pairs for multiplex PCR and the low specificity of published specific primers for P nicotianae and P cactorum, new spe- cies-specific primers for P nicotianae and P cactorum were designed based on the internal transcribed spacer regions of ribosomal DNA and the ras-related protein gene Yptl, respectively. Specificity of the de- signed primers was demonstrated using 68 isolates, including Phy- tophthora spp., Pythium spp., and other soilborne pathogens. Multiplex PCR discriminated between P nicotianae and P cactorum in DNA mixtures of mycelia of the two species. Moreover, both species were detected in artificially and naturally infested soils, indicating that these markers can be used in diagnosis of strawberry diseases. For investiga- tion of the geographic distribution of the two pathogens in Japan, soil samples were collected in 89 strawberry fields from eight prefectures (Gifu, Saga, Nara, Tochigi, Chiba, Shizuoka, Yamanashi, and Hok- kaido) of Japan. The method that was developed was successfully ap- plied to survey P nicotianae and P cactorum, and distribution of the two pathogens in strawberry plantings in Japan was determined. [ABSTRACT FROM AUTHOR]