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1.
2.
Hiroshi Shiotani Terutaka Yoshioka Masashi Yamamoto Ryoji Matsumoto 《Journal of General Plant Pathology》2008,74(2):133-137
Susceptibility to Xanthomonas
axonopodis pv. citri of a citrus cybrid, in which the nuclear and cytoplasmic genomes were derived from Citrus
sinensis and C. unshiu, respectively, was evaluated. Bacterial growth in the leaves of the cybrid was similar to that in C. sinensis after pin-prick inoculation throughout the experiment, whereas growth was greater than that in C. unshiu from 8 days after inoculation. Lesion expansion and pustules that later developed from the lesions on the cybrid and on C. sinensis also appeared to be greater than those on C. unshiu. The incidence of citrus canker disease caused by the bacteria on the cybrid trees was in the field was equivalent to that
on C. sinensis but was severer than on C. unshiu. These results indicate that the nuclear genome of the cybrid plays a critical role in susceptibility to citrus canker disease.
However, the pathogenicity gene pthA of the bacteria is not likely to be involved in the difference in susceptibility to the bacteria between C. unshiu and C. sinensis because their susceptibility to a pthA-deficient mutant of the bacteria also differs. 相似文献
3.
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
4.
Hsin-Cheng Lin Yu-An Chang Hsiang Chang 《European journal of plant pathology / European Foundation for Plant Pathology》2013,137(4):677-688
Three novel atypical symptom-producing types of Xanthomonas axonopodis pv. citri were described recently. The variants designated as Xac-Ap type produce large flat necrotic with water-soaked margin lesions instead of canker lesions on leaves of Mexican lime (Citrus aurantifolia) and grapefruit (C. paradisi). Random mutagenesis using transposon Tn5 in Xac-Ap type strain XL38 was used to isolate a virulence-deficient mutant T38, which induced small flat necrotic with water-soaked margin lesions on leaves. PthAp being inactivated by the transposon was cloned and characterized. Our result demonstrated that pthAp is responsible for XL38 to cause large flat necrotic with water-soaked margin lesions and bacterial multiplication but fails to confer the ability of inducing canker lesions. Sequence analysis reveled pthAp is a new member belong to the pthA homologs. The sequence is almost identical to the other homologs except for the number of direct tandem repeats in the central region of the gene. The pthAp contained an intact promoter and a full-length reading frame but with 18.5 direct repeats. Moreover, the amino acid at position 3rd in 1st, 2nd, 3rd repeats and at 13th position in 11th, 12th, 13th, 14th repeats were varied. Mutant T38 is fully complemented by pthA carried 17.5 direct repeats for the pathogenicity of X. axonopodis pv. citri to elicit canker lesions. The pthAp affected in planta bacterial growth and lesions in size but no ability of inducing canker symptom. These results suggested that pthAp is a new distinct virulence effector responsible for the enhancement of virulence. 相似文献
5.
Jose Francisco L. Figueiredo Gerald V. Minsavage James H. Graham Frank F. White Jeffrey B. Jones 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(3):339-347
Xanthomonas citri subsp. citri, the causal agent of citrus canker, relies extensively on a type III secretion system for infection by delivering type III
effectors into host cells. In the genus Xanthomonas, two major regulators, HrpG and HrpX, are involved in the expression of genes encoding the type III secretion system. Twenty-three
candidate type III effectors were identified as targets for analysis. The involvement in pathogenicity of 20 candidate effector
genes in X. citri strain 306 (Xcc-306) was investigated using site-directed mutagenesis. Pathogenicity assays in grapefruit of 19 genes using
site-directed mutagenesis revealed that none of the mutants demonstrated to have reduced ability to cause canker disease.
A mutation in the TAL effector pthA4
–
resulted in loss of hypertrophy although no changes were observed in bacterial growth in leaves. Mutations in hrpG, hrpX, or hrpA genes displayed a complete loss of pathogenicity. Moreover, all mutants maintained the ability to trigger a hypersensitive
response (HR) in non-host tomato. In contrast to previous studies, hrpG
–
, hrpX
–
and hrpA
–
mutants also retained the ability to elicit an HR in tomato, indicating the presence of an Hrp independent elicitor in Xcc-306. 相似文献
6.
Betiana S. Garavaglia Cecilia G. Garofalo Elena G. Orellano Jorgelina Ottado 《European journal of plant pathology / European Foundation for Plant Pathology》2009,123(1):91-97
Hsp70 and Hsp90 expression in response to high and low temperatures was studied in orange, the host plant of Xanthomonas axonopodis pv. citri and in a non-host resistant plant, pepper. As expected in both plants, the expression of these chaperones was induced at
high temperatures while at cold temperatures the response was chaperone and plant-dependent. Expression of Hsp70 and Hsp90
was analysed during citrus canker and no changes in their levels could be observed whereas pepper plants infiltrated with
the phytopathogen showed an increase in the levels of both chaperones. These results suggest that no changes in Hsp70 and
Hsp90 expression are necessary during the disease while they are increased in non-host resistance. 相似文献
7.
Luqman Qurata Aini Hisae Hirata Shinji Tsuyumu 《Journal of General Plant Pathology》2010,76(2):132-142
8.
Xi Huang Jinling Zhai Yuehua Luo Klaus Rudolph 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(4):461-469
A highly virulent strain (HVS) of Xanthomonas axonopodis pv. malvacearum (Xam) was first reported in Africa in 1983, infecting all commercial cultivars of cotton including the immune cv. ‘101–102B’.
The HVS was considered to be a new race of pathovar malvacearum (race 20). Here we studied a HVS (GSPB 2388) isolated in Sudan, which causes symptoms that clearly differed from the typical
angular water-soaked spots of bacterial bright of cotton. Our investigations showed that extracellular cellulase activity
of this HVS was higher than that of the control strain GSPB 1386 (race 18). Additionally, SDS-PAGE indicated that the HVS
cell wall contained short LPS molecules with fewer O-chain repeating units, lacking in GSPB 1386. The higher cellulase activity
and the distinct lipopolysaccharide of HVS are correlated with the higher virulence and deviating symptom formation. Rep-PCR
fingerprinting showed that the HVS was very closely related to other strains of Xam. 相似文献
9.
Xudong Zhang Marta I. Francis William O. Dawson James H. Graham Vladimir Orbović Eric W. Triplett Zhonglin Mou 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(1):91-100
Citrus canker, caused by the bacterial pathogen Xanthomonas citri subsp. citri (Xcc), is a serious leaf and fruit spotting disease affecting many important citrus cultivars including grapefruit and certain
sweet oranges. Currently, efficacious and economical disease control measures for highly susceptible citrus cultivars are
lacking. Development of commercial cultivars with greater field resistance to citrus canker is the optimum strategy for effective
disease management. In this study, we generated transgenic ‘Duncan’ grapefruit (DG) and ‘Hamlin’ sweet orange (Ham) expressing
the Arabidopsis NPR1 gene (AtNPR1), which is a key positive regulator of the long-lasting broad-spectrum resistance known as systemic acquired resistance (SAR).
Our results indicate that over-expression of AtNPR1 in citrus increases resistance to citrus canker and that the resistance is related with the expression levels of AtNPR1 in the transgenic plants. The line (DG 42-2) with the highest expression level of AtNPR1 was also the most resistant, which developed significant fewer lesions accompanied by a ten-fold reduction in Xcc population. The lesions developed on DG 42-2 were smaller and darker than those on the control and lacked callus formation.
These lesion phenotypes resemble those on canker resistant kumquats and canker susceptible citrus trees treated with SAR-inducing
compounds. Therefore, over-expression of AtNPR1 in citrus is a promising approach for development of more resistant cultivars to citrus canker. 相似文献
10.
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
11.
We examined the response of adzuki bean leaves to infection by Phytophthora vignae f. sp. adzukicola and determined whether inoculated leaves can be used to evaluate cultivar resistance. Detached adzuki bean leaves were inoculated
with zoospores, and the resulting symptoms were diagnosed. Resistant reactions were characterized by dark brown, speckled
lesions or a lack of symptoms, while susceptible reactions were characterized by water-soaked spreading lesions. In an inoculation
experiment using a combination of three differential cultivars and three races, the response of 10-day-old primary leaves
accurately differentiate between race-specific resistance and susceptibility of adzuki cultivars. 相似文献
12.
Xiu-Fang Hu Fei-Xiang Ying Yu-Bo He Yuan-Yuan Gao Hai-Min Chen Ji-Shuang Chen 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(3):305-310
Pinellia ternata is a traditional Chinese herb which has been used in China for over 1,000 years. A soft-rot disease characterized by water-soaked
lesions and soft-rot symptoms with a stinking odour was commonly observed in cultivated fields of this plant, and Pectobacterium-like bacteria were consistently isolated from the infected tissues. Two typical strains (SXR1 and ZJR1), isolated from Shanxi
and Zhejiang, respectively, were identified. Pathogenicity tests revealed that these strains were virulent to P. ternata and induced the same symptoms as observed in the field. Characterization involving fatty acid profile, metabolic and physiological
properties, 16S rDNA sequence and PCR-RFLP identified both isolates as P. carotovorum subsp. carotovorum (Pcc). The 16S rDNA of both isolates shared 97–99% sequence similarity with that of Pcc strains. The phylogenetic trees showed
that both isolates were clustered in the group of Pcc and P. carotovorum subsp. odorifera and both PCR-RFLP profiles were consistent with the pattern E produced by the minority of Pcc strains. Thus, isolates SXR1
and ZJR1 were characterized as Pcc in spite of some differences. This is the first report that Pcc has been proven as a causal
agent of soft-rot disease on P. ternata. 相似文献
13.
Franklin Behlau Jeffrey B. Jones Monty E. Myers James H. Graham 《European journal of plant pathology / European Foundation for Plant Pathology》2012,132(2):259-270
Streptomycin has been tested as an alternative to copper bactericides, which are routinely used for the control of citrus
canker (Xanthomonas citri subsp. citri, Xcc) in citrus producing areas where the disease is endemic. A major concern is that excessive use of copper as a bactericide
may lead to development of copper-resistant strains of Xcc. In this study, we developed a semi-selective medium to recover
copper or streptomycin-resistant strains of Xcc from citrus leaves. The newly developed semi-selective medium was used to
monitor the effect of a 21-day-interval copper or streptomycin spray program on Xcc for three consecutive seasons and on citrus
epiphytic bacterial populations for two seasons in a commercial grapefruit grove. Although, no copper- or streptomycin-resistant
strains of Xcc were isolated after three seasons, we observed a significant increase over time in the frequency of citrus
epiphytic bacteria resistant to these chemicals. Overall, the proportion of epiphytic bacteria resistant to streptomycin on
treated and untreated leaves was proportionally lower than the copper-resistant bacterial population. When application of
each bactericide was suspended for the season, the proportion of bactericide-resistant bacteria in the epiphytic population
decreased to that of the non-treated bacterial population. Availability of an alternative bactericide, such as streptomycin,
to integrate into a copper-based program would reduce the amount of each bactericide sprayed in citrus orchards and possibly
lower the selection pressure for bacterial resistance to these chemicals. 相似文献
14.
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
15.
Yong Zhang Yu Chen Xiaofeng Zhu Ying Xu Yiping Hou Tongchun Gao Mingguo Zhou 《Phytoparasitica》2011,39(4):393-401
Xanthomonas oryzae pv. oryzicola, the causal agent of rice leaf streak disease, was found to be sensitive to streptomycin (an aminocyclitol glycoside antibiotic),
by inhibition of protein synthesis resulting from interference with translational proofreading. This study aimed to determine
the molecular resistance mechanism of X. oryzae pv. oryzicola to streptomycin. Seven streptomycin-resistant mutants were obtained by UV induction or streptomycin selection. These mutants
can grow at 100 μg ml−1 of streptomycin while the wild-type strain (RS105) cannot grow at 5 μg ml−1. Sequencing indicated that the rpsL gene encoding ribosomal protein S12 has 375 bp encoding 125 amino acid residues. In all resistant strains, a mutation in
which AAG was substituted for AGG (Lys→Arg) occurred either at codon 43 or 88. Two plasmids, pUFRRS and pUFRRX, were constructed
by ligating the rpsL gene into the cosmid pUFR034. The plasmids pUFRRS and pUFRRX containing the Lys→Arg mutation of the rpsL gene conferred streptomycin resistance to the sensitive wild-type strain by electroporation. Both transformants, RS1 and
RS2, could grow in the medium containing 50 μg ml−1 of streptomycin. A mutation at codon 43 or 88 in rpsL can result in resistance of Xanthomonas oryzae pv. oryzicola to streptomycin. 相似文献
16.
M. Figen Donmez Huseyin Karlidag Ahmet Esitken 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(2):241-247
Bacterial canker caused by Pseudomonas syringae pv. syrinage (Pss) in apricot has widely spread in Turkey, especially in Malatya province, in recent years. The main objective of this study was to determine resistance of apricot cultivars to bacterial canker caused by Pss in apricot cultivars grown in Turkey. During the 2006–2007 growing period, bacterial isolations were taken from diseased apricot trees in Malatya and 53 Pseudomonas syringae isolates were obtained. Forty-two isolates were determined as Pseudomonas syringae pv. syringae and 11 isolates as pv. morsprunorum. In a pathogenicity test, leaves of cv. Hacihalilo?lu were used and five Pss isolates (K24, K25, K43, K47 and K51) were detected to be the most virulent and were used to test for cultivar resistance to Pss. Leaves of fifteen apricot cultivars (Alyanak, Çatalo?lu, Çölo?lu, Erken A?erik, Hacihalilo?lu, Hasanbey, ?smaila?a, Kabaa?i, Karacabey, Sakit 2, So?anci, ?am, ?ekerpare, Tokalo?lu (Erzincan) and Turfanda Eski Malatya) were tested for resistance to Pss. Green shoots were spray-inoculated with a concentration of 108 cfu ml?1 Pss mixed culture. Sprayed shoots were covered with moist plastic bags for 3 days and maintained in the growth chamber and monitored for symptom development. Hasanbey, Çölo?lu, So?anci and ?ekerpare apricot cultivars were resistant and ?am, Tokalo?lu (Erzincan) and Erken A?erik apricot cultivars were susceptible to Pss. This is the first report of a resistance source in apricot cultivars grown in Turkey against Pss. 相似文献
17.
Susan J. Sprague Barbara J. Howlett John A. Kirkegaard 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(2):189-202
The infection of above-ground tissues of Brassica napus by Leptosphaeria maculans is well understood. However, root infection (root rot) under field conditions, the development of root rot over time and
its relationship to other disease symptoms caused by L. maculans has not been described. A survey of B. napus crops was conducted in Australia to investigate the incidence and severity of root rot. Additionally, the pathway of root
infection was examined in field experiments. Root rot was present in 95% of the 127 crops surveyed. The severity and incidence
of root rot was significantly correlated with that of crown canker; however, the strength of this relationship was dependent
on the season. Root rot symptoms appeared before flowering and increased in severity during flowering and at maturity, a pattern
similar to crown canker suggesting that the infection of the root is an extension of the crown canker phase of the L. maculans lifecycle. All isolates of L. maculans tested in glasshouse experiments caused root rot and crown canker in B. napus and Brassica juncea. In the field, the main pathway of root infection is via invasion of cotyledons or leaves by airborne ascospores, rather
than from inoculum in the soil. Root rot was present in crops in fields that had never been sown to B. napus previously, in plants grown in fumigated fields, and in glasshouse-grown plants inoculated in the hypocotyl with L. maculans. 相似文献
18.
S. Mahadevakumar C. Chandana Y. S. Deepika K. S. Sumashri Vandana Yadav G. R. Janardhana 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(4):1081-1087
A severe outbreak of southern blight disease of China aster was observed during the post rainy season (September–November 2015) in the Mysore and Mandya Districts of Karnataka, Southern India. The disease incidence ranged between 12 and 47%. The typical disease symptoms include water-soaked lesions on leaves, stems and on the lower stem surfaces followed by quick wilting of the whole plant with abundant production of sclerotia near the stem-soil interface. The associated fungal pathogen was isolated on potato dextrose agar (PDA) medium, on which numerous reddish-brown sclerotia were seen. A total of 26 fungal isolates were isolated and studied for the mycelial compatibility. Isolate SrCCM 1 was used for pathogenicity analysis. The results of the study showed that, there was no variation among the isolates tested. Molecular identification of the pathogen by ITS-rDNA sequences of S. rolfsii showed 100% similarity with reference sequences. Based on the cultural, morphological and molecular characteristics, the fungal pathogen was identified as Sclerotium rolfsii Sacc. (Sexual morph: Athelia rolfsii (Curzi) C.C. Tu & Kimbr). Pathogenicity tests were performed on healthy leaves, roots and stems. Typical disease symptoms on leaves, stems and roots were evident after 5, 8 and 10 days of post-inoculation. Sclerotium rolfsii is known to cause diseases in economically important crop plants. However, no reports are available on the occurrence of S. rolfsii on China aster in India. 相似文献
19.
Davide Giovanardi Davide Dallai Emilio Stefani 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(4):761-771
Bacterial leaf/fruit spot and canker of stone fruits, caused by Xanthomonas arboricola pv. pruni, is a recurrent disease in Italy. A set of 23 strains has been isolated in peach and plum orchards in an intensively stone fruit cultivated area located in north-eastern Italy. They were all identified as X. arboricola pv. pruni by means of phytopathological and serological features: hypersensitive reaction on bean pods, pathogenicity test on immature peach or plum fruitlets, identification by immunofluorescence assay and conventional PCR. Phylogenetic analysis based on sequencing of the gyrB housekeeping gene of the isolates showed that they formed a unique clade, well characterised and separated from other xanthomonads. An insight into the genetic population features was attempted by rep-PCR analysis, using the ERIC, REP and BOX primers. The combined rep-PCR fingerprints showed a slight intra-pathovar variation within our isolates, which grouped in five close clusters. Copper resistance has been assessed in vitro for our whole X. arboricola pv. pruni collection, highlighting that two isolates show a level of resistance in vitro up to 200 ppm of copper. Nonetheless, the copLAB gene cluster, present in many other species of Xanthomonads, was not detected in any isolate, confirming the presence of a still unknown mechanism of copper detoxification in our Xanthomonads arboricola pv. pruni tolerant/resistant strains. 相似文献
20.
Yoshiyuki Makizumi Mitsuru Igarashi Kiyotaka Gotoh Kazunori Murao Momoe Yamamoto Nutthawoot Udonsri Hirokazu Ochiai Petcharat Thummabenjapone Hisatoshi Kaku 《Journal of General Plant Pathology》2011,77(1):24-32
Bacterial fruit blotch of cucurbits is a destructive disease caused by Acidovorax avenae subsp. citrulli, which is a typical seedborne pathogen. In seed health testing for this disease, we have detected many strains of Acidovorax with some differences from A. avenae subsp. citrulli. Their 16S rRNA sequences were divided into six types. The most common sequence was completely consistent with that of A. avenae subsp. avenae originally isolated from rice. The other sequences were over 99% similar but not identical to those of A. avenae subsp. avenae and A. avenae subsp. citrulli. Some commercialized antibodies against A. avenae subsp. citrulli reacted with several of these strains. Some of these strains incited yellow spots or brownish water-soaked lesions mainly
on young true leaves of cucumber and squash after spray inoculation. Histological observations showed that these strains entered
the leaf tissues of cucurbit plants through stomata and multiplied in the intercellular spaces of parenchymatous tissues as
well as in the vascular tissues. The amount of bacterial multiplication and spread in the tissues differed among the strains,
presumably reflecting their ability to induce symptoms. These isolated strains are therefore different from A. avenae subsp. citrulli, and their potential threat to the cultivation of cucurbits is lower than that of A. avenae subsp. citrulli. 相似文献