• Journal of Microbiology and Biotechnology
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• v.15 no.3
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• pp.502-509
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• 2005

Sexual reproduction plays an important role in the biology and epidemiology of oomycete plant pathogens such as the heterothallic species Phytophthora infestans. Recent worldwide dispersal of A2 mating type strains of P. infestans resulted in increased virulence, gene transfer, and genetic variation, creating new challenges for disease management. To develop a genetic assay for mating type identification in P. infestans, we used the Amplified Fragment Length Polymorphism (AFLP) technique. The primer combination E+AT/M+CTA detected a fragment specific to A1 mating type (Mat-A1) of P. infestans. This fragment was cloned and sequenced, and a pair of primers (INF-1, INF-2) were designed and used to differentiate P. infestans Mat-A1 from Mat-A2 strains. The Mat A1-specific fragment was detected using Southern blot analysis of PCR products amplified with primers INF-1 and INF-2 from genomic DNA of 14 P. infestans Mat-A1 strains, but not 13 P. infestans Mat-A2 strains or 8 other isolates representing several Phytophthora spp. Southern blot analysis of genomic DNAs of P. infestans isolates revealed a 1.6 kb restriction enzyme (EcoRI, BamHI, AvaI)-fragment only in Mat-A1 strains. The A1 mating type-specific primers amplified a unique band under stringent annealing temperatures of $63^{\circ}C-64^{\circ}C$, suggesting that this PCR assay could be developed into a useful method for mating type determination of P. infestans in field material.

• Journal of Microbiology
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• v.40 no.4
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• pp.254-259
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• 2002

The Phytophthora infestans requires two mating types for sexual reproduction. Amplified fragment length polymorphism (AFLP) was used to specifically detect different mating types of P. infestans. The AFLP primers E+AA (5'-GACTGCGTACCAATTCAA-3') and M+CAA (5'-GATGAGTCCTGAG-TAAC AA-3') detected a fragment that is specific in the A2 mating type of P. infestans. This fragment was cloned and sequenced. Based on the sequence data, PHYB-1 and PHYB-2 primer were designed to detect the A2 mating type of P. infestans. A single 347 bp segment was observed in the A2 mating type of P. infestans, but not in the A1 mating type of P. infestans or other Phytophthora spp. Identification of mating type was performed with phenotype (sexual reproduction) and genotype (CAPs marker) methods. Two factors, the annealing temperature and template DNA quantity, were investigated to determine the optimal conditions. Using mating type-specific primers, a unique band was obtained within annealing temperatures of 57$^{\circ}C$-62$^{\circ}C$ and DNA levels of 10pg-100 ng (data not shown).

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.26-26
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• 2015

Phytophthora infestans is the causal agent of potato and tomato late blight, one of the most devastating plant diseases. P. infestans secretes effector proteins that are both modulators and targets of host plant immunity. Among these are the so-called RXLR effectors that function inside plant cells and are characterized by a conserved motif following the N-terminal signal peptide. In contrast, the effector activity is encoded by the C terminal region that follows the RXLR domain. Recently, I performed in planta functional profiling of different RXLR effector alleles. These genes were amplified from a variety of P. infestans isolates and cloned into a Potato virus X (PVX) vector for transient in planta expression. I assayed for R-gene specific induction of hypersensitive cell death. The findings included the discovery of new effector with avirulence activity towards the Solanum bulbocastanum Rpi-blb2 resistance gene. The Rpi-blb2 encodes a protein with a putative CC-NBS-LRR (a coiled-coil-nucleotide binding site and leucine-rich repeat) motif that confers Phytophthora late blight disease resistance. We examined the components required for Rpi-blb2-mediated resistance to P. infestans in Nicotiana benthamiana. Virus-induced gene silencing was used to repress candidate genes in N. benthamiana and to assay against P. infestans infections. NbSGT1 was required for disease resistance to P. infestans and hypersensitive responses (HRs) triggered by co-expression of AVRblb2 and Rpi-blb2 in N. benthamiana. RAR1 and HSP90 did not affect disease resistance or HRs in Rpi-blb2-transgenic plants. To elucidate the role of salicylic acid (SA) in Rpi-blb2-mediated resistance, we analyzed the response of NahG-transgenic plants following P. infestans infection. The increased susceptibility of Rpi-blb2-transgenic plants in the NahG background correlated with reduced SA and SA glucoside levels. Furthermore, Rpi-blb2-mediated HR cell death was associated with $H_2O_2$, but not SA, accumulation. SA affects basal defense and Rpi-blb2-mediated resistance against P. infestans. These findings provide evidence about the roles of SGT1 and SA signaling in Rpi-blb2-mediated resistance against P. infestans.

• Journal of Microbiology
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• v.39 no.2
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• pp.126-132
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• 2001

For rapid and secure differentiation of P. infestans from other Phytophthora species, two fragments obtained from randomly amplified polymorphic DNA (RAPD) profiles were selected as markers. Also, primers for in polymerase chain reaction (PCR) to detect P. infestans specifically were developed by analyzing the sequences of ITSII regions in rDNA of Phytophthora species. The primers, PISP-1 and ITS3 amplified a single. Fragment 450 bp of about in P. infestans, but not in other fungal or bacterial isolates. Annealing temperatures and template DNA quantities were varied for the optimization of PCR conditions. From the result of the PCR detection study, species-specific primers were selected under annealing temperatures ranging from 55$^{\circ}C$ to 61$^{\circ}C$, and template DNA levels ranging from 10 pg to 100 ng.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.724-730
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• 2006

A sequence characterized amplified region (SCAR) marker, which was tightly linked with the A1 mating type locus in Phytophthora infestans, was developed. During the random amplified polymorphic DNA-based phylogenic studies of 33 isolates of P infestans collected from year 2002 to 2004, we found an A1 mating type-specific DNA fragment. This 573-bp DNA fragment was generated only in the genomic DNA of the A1 mating types, when OPC-5 primer was used. Based on the specific DNA sequence, we designed the primer sets for generating the A1 mating type-specific 569-bp DNA fragment. When 33 genomic DNAs of P. infestans were subjected to PCR amplification using different primer combinations, the A1 mating type-specific DNA was amplified, when LB-1F and LB-2R primers were used. The specific 569-bp DNA fragment was generated only from all 18 A1 strains, but not from 15 A2 mating type strains. These results corresponded to the mating type discriminating bioassay of 33 isolates of P. infestans. Therefore, the primer combination of LB-1F/LB2R was chosen as a SCAR marker. Overall, this study indicates that the SCAR marker could be developed into a useful tool for mating type determination of P. infestans.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.442-446
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• 2005

Fungicidal activities of Cassia obtusifolia extracts and their active principles were tested against Botrytis cinerea, Erysiphe graminis, Phytophthora infestans, Puccinia recondita, Pyricularia grisea, and Rhizoctonia solani, and compared with synthetic fungicides and two dihydroxyanthraquinones. At 1 g/l, the chloroform fraction of C. obtusifolia extracts showed fungicidal activity against B. cinerea, E. graminis, P. infestans, and Py. grisea, and the ethyl acetate fraction showed fungicidal activity against E. graminis and P. infestans. Danthrone was chromatographically isolated from the chloroform fraction and showed fungicidal activity against B. cinerea, E. graminis, P. infestans, and Py. grisea with 68, 100, 78, and $91\%$ control values at 0.5 g/l, respectively. Specifically, alizarin and quinizarin inhibited E. graminis, P. infestans, and Py. Grisea, but did not inhibit the growth of P. recondita and R. solani. These results indicate at least one of the fungicidal actions of danthrone.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.116.2-117
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• 2003

Late blight, caused by Phytophthora infestans, is one of the most destructive disease on potato and tomato cultivation. To analysis genetic diversity P. infeatans isolates were collected from potato and tomato fields in Korea. These pathogens contained both Al and A2 mating type with metalaxyl-resistant and sensitive isolates. Polymorphisms showed base on RAPD (Random Amplified Polymorphic DNA) in both potato and tomato isolates of P. infestans. Cluster analysis showed high level genetic variation in potato isolates of P. infestans than tomato isolates. P. infestans isolates were observed genetic diversity among them but not grouped among isolates related mating type and metalaxyl response. These results exhibited that P. infestans isolates showing genetic difference among them were distributed in Korea.

• The Plant Pathology Journal
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• v.25 no.1
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• pp.103-107
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• 2009

In the course of a searching natural antifungal compounds from plant seeds, we found that the methanol extract of Psoralea corylifolia seeds showed potent control efficacy against tomato late blight caused by Phytophthora infestans and wheat leaf rust Puccinia recondita. Under bioassay-guided purification, we isolated two furanocoumarins, psoralen and isopsoralen, with anti-oomycete activity against P. infestans. By 1-day protective application, both compounds strongly reduced the disease development of P. infestans on tomato seedlings, but hardly controlled development of leaf rust on wheat seedlings. This is the first report on the anti-oomycete activity of P. corylifolia as well as that of psoralen and isopsoralen.

• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.651-655
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• 2000

Polymerase chain reaction (PCR) was used to specifically detect Phytophthora infestans by analyzing the sequences of the ribosomal internal transcribed spacer regions (ITS) in the rDNA of the Phytophthora species. Based on the sequence data, PISP-1 together with the ITS3 primer were used to detect p. infestans. A single ca. 450 bp segment was observed in P. infestans, but not in the other fungal or bacterial isolates. Two factors, the annealing temperature and template DNA quantity, were investigated to determine the optimal conditions. Using these species-specific primers, a unique band was obtained within annealing temperatures of $55^{\circ}C$-$61^{\circ}C$ and template DNA levels of 10 pg-100 ng.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.219-222
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• 2007

A total of the 261 Phytophthora infestans isolates collected from 2003 to 2005 in Korea were investigated for their physiological race composition. Among the isolates, we detected 18 physiological races and the dominant races were R0.1.3.5.6.10.11 and R0.1.3.5.6.7.10.11 with frequencies of 18.4% and 11.4%, respectively. All of the P. infestans races carried multiple virulence genes and showed virulence to the potato resistance genes R1, R3, R5, R6, R7, R10 and R11, but not to R8 and R9. Therefore, it is likely that the physiological races of P. infestans were diverse in Korea.