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In many Gram-negative plant pathogenic bacteria the type III secretion system (TTSS), encoded by hrp genes, is essential for pathogenicity in the host and induction of a hypersensitive reaction (HR) in nonhost plants. The expression of hrp genes has been suggested to be repressed in complex media, whereas it is induced in planta and under certain in vitro conditions. We recently reported that XOM2 medium allows efficient hrp expression by Xanthomonas oryzae pv. oryzae. In this study, we investigated hrp-dependent secretion of proteins by the bacteria in vitro. Using modified XOM2, in which bovine serum albumin was added and the pH was lowered to 6.0, we detected at least 10 secreted proteins and identified one as Hpa1. This is the first evidence of protein secretion via TTSS in X. oryzae pv. oryzae. 相似文献
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Chun-Lian Wang An-Bi Xu Ying Gao Ying-Lun Fan Yun-Tao Liang Chong-Ke Zheng Liang-Qing Sun Wen-Quan Wang Kai-Jun Zhao 《European journal of plant pathology / European Foundation for Plant Pathology》2009,123(3):343-351
Xanthomonas oryzae pv. oryzae causes bacterial blight of rice. Xa23, a bacterial blight resistance gene identified originally in wild rice, Oryza rufipogon, is dominant and resistant to all X. oryzae pv. oryzae field isolates tested. The corresponding avirulence gene avrXa23 is unknown. Here we report the generation of a random insertion mutant library of X. oryzae pv. oryzae strain PXO99 using a Tn5-derived transposon tagging system, and identification of mutant strains that are virulent on CBB23,
a near-isogenic rice line containing Xa23. A total of 24,192 Tn5 inserted clones was screened on CBB23 by leaf-cutting inoculation and at least eight of them caused
lesions on CBB23 comparable to those on JG30, the susceptible recurrent parent of CBB23. Polymerase chain reaction and Southern
blot analysis showed that all the eight mutants, designated as P99M1, P99M2, P99M3, P99M4, P99M5, P99M6, P99M7 and P99M8,
have a single Tn5-insertion in their genomes. The flanking DNA sequences of the Tn5-insertion sites were isolated by PCR-walking
and sequenced. Bioinformatic analysis of the flanking sequences, by aligning them with the whole genome sequences of X. oryzae pv. oryzae strains PXO99, KACC10331 and MAFF311018 through NCBI, revealed that the Tn5-insertions disrupted genes that encode TAL effector
AvrBs3/PthA, ISXo1 transposase, Type II secretion system protein-like protein or outer membrane protein, glycogen synthase,
cytochrome C5 and conserved hypothetical protein. Further identification of these mutants will facilitate the molecular cloning
of avirulence gene avrXa23.
The authors C.-L. Wang, A.-B. Xu contributed equally to this work; Y. Gao and Y.-L. Fan contributed equally to this work. 相似文献
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The clustered hrp genes encoding the type III secretion system in the Japanese strains MAFF301237 and MAFF311018 of Xanthomonas oryzae pv. oryzae were sequenced and compared. The strains differ in their pathogenicity, location, and year of isolation. A 30-kbp sequence comprising 29 open reading frames (ORFs) was identical in its structural arrangement in both strains but differed from X. campestris pv. campestris, X. axonopodis pv. citri, and X. axonopodis pv. glycines in certain genes located between the hpaB-hrpF interspace region. The DNA sequence and the putative amino acid sequence in each ORF was also identical in both X. oryzae pv. oryzae strains as were the PIP boxes and the relative sequences. These facts clearly showed that the structure of the hrp gene cluster in X. oryzae pv. oryzae is unique. 相似文献
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Population structure of Eleusine isolates of Pyricularia oryzae (Magnaporthe oryzae) was examined using DNA markers. On the basis of rDNA sequences, Eleusine isolates were divided into two groups. One group clustered with Triticum isolates, while the other clustered with Eragrostis isolates. This grouping was supported by DNA fingerprinting with three repetitive elements: MGR586, MGR583, and grasshopper. These results suggest that the population of Eleusine isolates is composed of at least two groups that evolved independently from the original population of P. oryzae. Most of the isolates that were collected just after an outbreak of finger millet blast in the 1970s had almost identical
fingerprint profiles although they were collected in distant prefectures. This result supports the idea that the outbreak
was caused by seed transmission of a particular strain of Eleusine isolates. 相似文献
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The present study was conducted to determine if there is specificity in the host-pathogen relationship between the isolates
of Xanthomonas oryzae pv. oryzae, the causal bacterium for rice blight and Leersia grasses, the alternative weed hosts of the disease. Plants of three species of Leersia, namely, L. sayanuka, L. oryzoides and L. japonica, were collected from various parts of Japan and were inoculated with the X. oryzae pv. oryzae isolates obtained from various locations in Japan and from 11 Asian countries. Four L. sayanuka plants were found susceptible to all Race II isolates and some Race I isolates, but were resistant to all Race III isolates.
Race III is known to have a wider range pathogenicity to rice cultivar groups compared with Race I and II. Although the reactions
of two L. oryzoides plants to Race I and II isolates were similar to that of L. sayanuka, the L. oryzoides plant collected from Niigata Prefecture showed a susceptible reaction to some Race III isolates. On the other hand, L. japonica plants gave reactions different those of L. sayanuka and L. oryzoides, with two plants of L. japonica found to be resistant to all test isolates collected from Japan. The Asian isolates exhibited a wide host range against the
international differential rice cultivars, but almost all of them were avirulent to Leersia plants. These results indicate that the relationship between the pathogenicity of the causal bacterium and the resistance
of host plants is very complex, and suggest that pathogenic diversity of X. oryzae pv. oryzae might be related to the resistance of Leersia spp. 相似文献
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Phialophora gregata f. sp. adzukicola, a causal agent of brown stem rot in adzuki beans, produces phytotoxic compounds: gregatins A, B, C, D, and E. Gregatins
A, C, and D cause wilting and vascular browning in adzuki beans, which resemble the disease symptoms. Thus, gregatins are
considered to be involved in pathogenicity. However, molecular analyses have not been conducted, and little is known about
other pathogenic factors. We sought to isolate nonpathogenic and gregatin-deficient mutants through Agrobacterium tumefaciens-mediated transformation (ATMT) for cloning of pathogenicity-related genes. The co-cultivation of P. gregata and A. tumefaciens for 48 h at 20°C with 200 μM acetosyringone resulted in approximately 80 transformants per 106 conidia. The presence of acetosyringone in the A. tumefaciens pre-cultivation period led to an increase in T-DNA copy number per genome. Of 420 and 110 transformants tested for their
pathogenicity and productivity of gregatins, one nonpathogenic and three gregatin-deficient mutants were obtained, respectively.
The nonpathogenic mutant produced gregatins, whereas the gregatin-deficient mutants had pathogenicity comparable to the wild-type
strain. This is the first report of ATMT of P. gregata. Further analysis of these mutants will help reveal the nature of the pathogenicity of this fungus including the role of
gregatin in pathogenesis. 相似文献
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Takeshi Toda Toshihiro Hayakawa Joseph Mwafaida Mghalu Shigeharu Yaguchi Mitsuro Hyakumachi 《Journal of General Plant Pathology》2007,73(6):379-387
Isolates of an unidentified Rhizoctonia sp. (UR isolates) were obtained from creeping bentgrass and Kentucky bluegrass with reddish brown sheath and foliar rots.
Because the UR isolates anastomosed with isolates of three varieties of Waitea circinata (var. oryzae, var. zeae, and var. circinata), colony morphology, hyphal growth rate at different temperatures, pathogenicity, sequence analysis of the internal transcribed
spacers (ITS) region of ribosomal RNA genes (rDNA) were compared. The colony color of mature UR isolates was distinct from
isolates of the other three varieties of W. circinata. In pathogenicity tests on creeping bentgrass, the severity of the disease caused by UR isolates was significantly higher
than that caused by the three varieties of W. circinata. Sequence similarities of the rDNA-ITS region between UR isolates and between isolates within each variety were high (97–100%),
but they were lower among isolates from UR and the varieties of W. circinata (88–94%). In a phylogenetic tree based on the rDNA-ITS sequences, UR isolates formed a cluster separate from each of the
clusters formed by the three varieties of W. circinata. These results indicate that the UR isolates clearly differ from the three varieties of W. circinata. We therefore propose that the UR isolates be classified as new Rhizoctonia sp. that are closely related to W.
circinata and that the disease on creeping bentgrass should be called Waitea reddish-brown patch disease (Sekikasshoku-hagusare-byo
in Japanese). 相似文献
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Essential oils extracted fromEucalyptus blakelyi (1,8-cineole, 77.5%),Melaleuca fulgens (1,8-cineole, 56.9%) and 1,8-cineole were shown to have fumigant toxicity against different development stages ofSitophilus oryzae. The eggs ofS. oryzae were the most tolerant, followed by pupae, larvae and adults in that order.M. fulgens oil,E. blakelyi oil and 1,8-cineole at 100 μl per liter of air gave, respectively, LT50 values of 16.2, 17.4 and 9.1 h for adults, 31.1, 19.3 and 17.5 h for larvae, 55.6, 75.2 and 39.7 h for pupae, and required
>7 days for eggs. Only 1,8-cineole (200 μl
−1 air) gave a significant egg kill by 7 days and the LT95 was 134.5 h. 1,8-Cineole could be a useful new fumigant.
http://www.phytoparasitica.org posting Oct. 3, 2004. 相似文献
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Kerstin Wydra Gopal Khatri-chhetri Athanassios Mavridis Rachidatou Sikirou Klaus Rudolph 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(10):991-1001
A semi-selective medium for isolation of Xanthomonas axonopodis pv. vignicola from cowpea (Vigna unguiculata) plant and soil samples was developed. Twelve carbon and five nitrogen sources were tested with four strains of X. axonopodispv.vignicola, and 25 antibiotics were screened against saprophytes. -cellobiose (10g) was selected as the optimal carbon source. Among the antibiotics, cefazoline inhibited growth of most of the saprophytes with little effect on strains of the pathogen. ,-methionine enhanced growth of X. axonopodispv.vignicola. Boric acid along with ammonium chloride suppressed growth of Pseudomonas fluorescens. The semi-selective medium designated as cefazoline-cellobiose-methionine (CCM) medium contained K2HPO4 1.34g, KH2PO4 0.4g, MgSO4 0.3g, H3BO3 0.2g, NH4Cl 1.0g, -cellobiose 10g, cycloheximide 0.2g, ,-methionine 1.0g, cefazoline 10mg and agar 14g per l of water (pH 7.2). Colonies of X. axonopodispv.vignicola on CCM medium were whitish, round, raised and 0.2–1.8mm in diameter 96h after incubation. CCM medium generally inhibited growth of Pantoea agglomerans, Bacillus subtilis and saprophytes isolated from cowpea leaves. Colonies of Pseudomonas fluorescens and a saprophytic bacterium, which were not completely suppressed by CCM, could be differentiated from X. axonopodispv.vignicola by their smaller size and different color. The CCM medium proved useful for isolation of X. axonopodispv.vignicola from cowpea plant and soil samples. This is the first report of a semi-selective medium developed for detection of X. axonopodispv.vignicola. 相似文献
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Rui Yang Yong Chao Han Guo Qing Li Dao Hong Jiang Hung Chang Huang 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(4):411-420
A study was conducted to investigate production of antifungal substances (AFS) by Coniothyrium minitans (Cm), a mycoparasite of Sclerotinia sclerotiorum (Ss), in modified Czapek-Dox (MCD) broth and potato dextrose broth (PDB), and effects of AFS of Cm on mycelial growth and
germination of sclerotia and ascospores of Ss and incidence of leaf blight of oilseed rape caused by Ss. Results showed that
mycelial growth of Ss was reduced by 41.6 and 84.5% on 3 day-old cultures grown on potato dextrose agar (PDA) amended with
10% (v v−1) of cultural filtrates of Cm grown in MCD (MCDcm) after incubation for 6 and 15 days, respectively, and by 2.7 and 15.7% on PDA amended with 10% (v v−1) of cultural filtrates of Cm grown in PDB for 6 and 15 days, respectively. In addition to retardation of mycelial growth,
morphological abnormality of Ss such as hyphal swellings and cytoplasm granulation were also observed in colonies grown on
PDA amended with cultural filtrates of MCDcm. Sclerotia of Ss soaked in the filtrates of MCDcm for 24 h remained viable, but their ability to undergo myceliogenic germination on PDA was delayed, compared to sclerotia
treated with MCD. Germination of ascospores of Ss was unaffected on PDA amended with 10% of the filtrates of MCDcm. However, germ tubes of Ss were shortened and deformed by the formation of hyphal swellings in the treatment of MCDcm. Treatment of leaves of oilseed rape with cultural filtrates of MCDcm reduced incidence of leaf blight caused by Ss, compared to the controls (water or MCD). This study suggests that AFS produced
by Cm plays an important role in the suppression of mycelial growth and germ-tube development of ascospores of Ss and that
there is potential for using AFS of Cm to control leaf blight of oilseed rape caused by ascospores of Ss. 相似文献
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Norio Nishimura 《Journal of General Plant Pathology》2007,73(5):342-348
Selective media without pentachloronitrobenzene were developed for quantitative assays of Fusarium
oxysporum in soils. Media Fo-G1 and Fo-G2 were effective for naturally infested soils, Fo-W1 and Fo-W2 for wild-type isolates in soils
containing a nitrate-nonutilizing (nit) mutant, and Fo-N1 and Fo-N2 for nit mutants. Selective media were made using ammonium citrate dibasic, l-sorbose, econazole nitrate, 25% iminoctadine triacetate solution and 50% tolclofos-methyl wettable powder for soil dilutions
of 100-fold or more (Fo-G1, FoW1 and Fo-N1) and 10-fold (Fo-G2, Fo-W2 and Fo-N2). Potassium chlorate was added to Fo-N1 and
Fo-N2. The efficacy for selectively isolating F. oxysporum was confirmed using six soils naturally infested with one of six formae speciales of F. oxysporum and with soil dilutions containing conidia of wild-type strains or nit mutants from the six formae speciales. On Fo-G1 and Fo-G2, most colonies of F. oxysporum were compact and round with purplish or reddish pigment in the reverse. Cylindrocarpon sp. formed colonies as large as those of F. oxysporum but were distinguishable by their colony morphology. Other contaminants such as F. solani, F. moniliforme, and Trichoderma were suppressed by medium ingredients and colonies of F. oxysporum. On Fo-W1 and Fo-W2, colony morphology of F. oxysporum and contaminants corresponded to that on Fo-G1 and Fo-G2, although F. oxysporum failed to produce the pigment. On Fo-N1 and Fo-N2, nit mutants formed clear colonies from 100- and 10-fold soil dilutions, respectively, and contaminants seldom formed large colonies. 相似文献
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Taro Mori Katsumi Ozaki Hiromi Matsusaki Naotaka Matsuzoe 《Journal of General Plant Pathology》2007,73(2):142-146
To study the behavior and mutation of Ralstonia solanacearum in Solanum toxicarium, which is resistant to bacterial wilt, S. toxicarium was grown in aseptic culture and inoculated with R. solanacearum. Although 60%–80% of the inoculated plants were wilting after 2 to 3 days, most wilted plants had recovered by 20 days after
inoculation. The pathogen was reisolated from over 98% of inoculated plant stems, but the percentage of recovery decreased
the closer the isolation sites were toward the upper stem sections. Three colony types, characterized as fluidal white, nonfluidal
red, and a mixture of fluidal white and nonfluidal red, were reisolated from the stems. Nonfluidal red colonies were less
virulent on tomato plants than fluidal white colonies. 相似文献
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Motoaki Kusaba Chao-Xi Luo Hiromi Hanamura Masakazu Misaka Taiga Mochida Yoshikatsu Fujita Yukio Tosa 《Journal of General Plant Pathology》2008,74(3):250-253
A Japanese differential rice cultivar K60 was tested with 114 F1 cultures of Magnaporthe oryzae from a cross between isolates 84R-62B and Y93-245c-2. Segregation patterns of avirulence and virulence in the progeny suggested
that avirulence on cv. K60 was controlled by a single gene derived from 84R-62B and tentatively named AvrK60. In the F1 population, AvrK60 cosegregated with avirulence gene AvrPik on a small 1.6-Mb chromosome of 84R-62B and with the 1.6-Mb chromosome itself. Therefore, we suggest that, along with AvrPik, AvrK60 is also located on the 1.6-Mb chromosome of 84R-62B. 相似文献
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Shin-ichi Fuji Nanae Mochizuki Masashi Fujinaga Makoto Ikeda Kouichi Shinoda Seiji Uematsu Hiromitsu Furuya Hideki Naito Fumiyoshi Fukumoto 《Journal of General Plant Pathology》2007,73(3):216-221
Alstroemeria plants were surveyed for viruses in Japan from 2002 to 2004. Seventy-two Alstroemeria plants were collected from Aichi, Nagano, and Hokkaido prefectures and 54.2% were infected with some species of virus. The
predominant virus was Alstroemeria mosaic virus, followed by Tomato spotted wilt virus, Youcai mosaic virus (YoMV), Cucumber mosaic virus (CMV), Alstroemeria virus X and Broad bean wilt virus-2 (BBWV-2). On the basis of nucleotide sequence of the coat protein genes, all four CMV isolates belong to subgroup IA. CMV
isolates induced mosaic and/or necrosis on Alstroemeria. YoMV and BBWV-2 were newly identified by traits such as host range, particle morphology, and nucleotide sequence as viruses
infecting Alstroemeria. A BBWV-2 isolate also induced mosaic symptoms on Alstroemeria seedlings. 相似文献
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Antonín Dreiseitl Junmei Wang 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(4):357-368
Four hundred and sixty-one isolates of Blumeria
graminis f.sp. hordei were obtained from eight populations occurring on cultivated barley (Hordeum
vulgare) at four geographically distant locations in China during 2003 and 2004. Their virulence frequency was determined on 30 differential
lines. No isolate was virulent on differential lines possessing the resistance genes Mla1, Mla3, Mla6, Mla7, Mla9, Mla12, Mla13, Mlat, Mlg, Mla10, Mla22, Mla23, Mlp1, Ml(N81) and Mlmw. Virulences to the first nine resistance genes are prevalent in Europe and constitute the main part of genetic distance between
Chinese and European populations. Conversely, no isolate was avirulent on the differential lines possessing the genes Mla8 and Ml(Ch). The frequencies of isolates overcoming the genes Mla2, Mla11, Mlk1 and Mlk2 were .4–9.3%, and frequencies of isolates overcoming the genes Mlh, MlLa, Ml(Bw), Mlra, Ml(Ru2), mlw, MlGa, MlWo and Mlnn ranged from 18.2% to 98.7%. Based on reactions of differential lines possessing the genes Mlk1, Mlh, MlLa, Ml(Bw), Mlra and Ml(Ru2), pathotypes were identified and diversity parameters calculated. Eleven of 22 detected pathotypes were found in both years
and comprised 94.6% of isolates. Generally, the populations from different locations in 1 year were more closely related than
populations collected from the same locations in different years. Complete effectiveness of the resistance genes, for which
no corresponding virulences were found, will allow Chinese breeders to access many modern European barley cultivars that are
fully resistant to powdery mildew in China, including those possessing the non-host resistance gene mlo. 相似文献
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Masato Kawabe Kazunori Katsube Takanobu Yoshida Tsutomu Arie Kenichi Tsuchiya 《Journal of General Plant Pathology》2007,73(5):353-359
Twenty-eight isolates of Fusarium oxysporum f. sp. spinaciae (FOS; the causal agent of spinach wilt) collected from Japan were assessed for mating type and subjected to phylogenetic analysis.
Mating type analysis revealed all isolates to be MAT1-2, suggesting that there is no sexual recombination within the population.
Phylogenetic analyses based on nucleotide sequences of the ribosomal DNA intergenic spacer (IGS) and the mating type locus
(MAT1) suggested that FOS is polyphyletic. The cluster analysis based on IGS showed four phylogenetic groups (S1–S4) among the isolates. Two distinct
lineages, S1 and S3, included FOS isolates both of the vegetative compatibility group (VCG) types, 0330 and 0331, demonstrating that VCG differentiation in
FOS may not necessarily reflect the phylogenetic relationships based on IGS and MAT1-2-1. 相似文献
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Olga Afanasenko Nina Mironenko Olga Filatova Doris Kopahnke Ilona Krämer Frank Ordon 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(3):267-280
The genetics of host-pathogen interactions in the Hordeum vulgare – P. teres f. teres pathosystem was studied in twelve resistant barley accessions, i.e. CI 9825, CI 9819, Diamond, CI 4922, CI 5401, Harbin,
c-8755, c-21849, c-8721 c-23874, c-19979, c-15811. F2 analyses of crosses with susceptible genotypes employing various isolates (from Europe, USA, Canada, and Australia) revealed
that resistance is mostly isolate-specific and controlled by one or two genes. Segregation in ascospore progeny from two crosses
between isolates of different origin revealed that avirulence in P. teres is also determined by one or two genes. An epistatic effect of suppressor genes on avirulence genes is proposed for the genetics
of virulence to Diamond, Harbin, CI 5401 and c-8721 in the fungal crosses D (181-6 × A80) and F (H-22 × 92-178/9). Segregation
in F2 of crosses of three new sources of resistance (c-23874, c-19979, c-15811) to the susceptible cv. Pirkka was studied in laboratory
and greenhouse tests by using seven P. teres isolates, i.e. 181-6, d8-3, d8-4, d9-1, d9-4, F4 and F74. In addition, virulence to these barley accessions of ascospore
progeny from crosses of the same isolates was studied. Based on these studies it was concluded that depending on the isolate
used, resistance of c-23874 is determined at least by two genes and in c-19979 and c-15811 by three genes. The results of
this parallel analyses of genetics of resistance and genetics of virulence allows the postulation of a gene–for–gene interaction
in the P. teres – H. vulgare pathosystem. 相似文献