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1.
Harsh Garg Linda M. Kohn M. Andrew Hua Li Krishnapillai Sivasithamparam M. J. Barbetti 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(3):305-315
Sclerotinia stem rot caused by Sclerotinia sclerotiorum is a serious threat to oilseed production in Australia. Eight isolates of S. sclerotiorum were collected from Mount Barker and Walkway regions of Western Australia in 2004. Comparisons of colony characteristics
on potato dextrose agar (PDA) as well as pathogenicity studies of these isolates were conducted on selected genotypes of Brassica napus and B. juncea. Three darkly-pigmented isolates (WW-1, WW-2 and WW-4) were identified and this is the first report of the occurrence of
such isolates in Australia. There was, however, no correlation between pigmentation or colony diameter on PDA with the pathogenicity
of different isolates of this pathogen as measured by diameter of cotyledon lesion on the host genotypes. Significant differences
were observed between different isolates (P ≤ 0.001) in two separate experiments in relation to pathogenicity. Differences were also observed between the different Brassica genotypes (P ≤ 0.001) in their responses to different isolates of S. sclerotiorum and there was also a significant host × pathogen interaction (P ≤ 0.001) in both experiments. Responses between the two experiments were significantly correlated in relation to diameter
of cotyledon lesions caused by selected isolates (r = 0.79; P < 0.001, n = 48). Responses of some genotypes (e.g., cv. Charlton) were relatively consistent irrespective of the isolates of the pathogen
tested, whereas highly variable responses were observed in some other genotypes (e.g., Zhongyou-ang No. 4, Purler) against
the same isolates. Results indicate that, ideally, more than one S. sclerotiorum isolate should be included in any screening programme to identify host resistance. Unique genotypes which show relatively
consistent resistant reactions (e.g., cv. Charlton) across different isolates are the best for commercial exploitation of
this resistance in oilseed Brassica breeding programmes. 相似文献
2.
Siamak Rahmanpour David Backhouse Heather M. Nonhebel 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(4):429-433
The glucosinolate-myrosinase defence system, specific to Brassicales plants, produces toxic volatile compounds during mechanical
injury or pathogen attack. The reaction of this system to oxalic acid, known as a pathogenicity factor of Sclerotinia sclerotiorum, is not fully understood. The hydrolysis of glucosinolates was studied at varying conditions in the presence of oxalic acid
in the substrate. In a bioassay, colonies of the pathogen were exposed to volatiles from hydrated mustard powder used as a
myrosinase and glucosinolate source. The glucosinolate-myrosinase (GSL-M) system was activated in the presence of oxalic acid
at a concentration and pH similar to that expected in vivo. Volatile production was inhibited only when the pH fell to 3 or below. It is unlikely that oxalic acid plays a significant
role in disarming the GSL-M system during infection of Brassica hosts. 相似文献
3.
R. Lebecka 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(2):345-348
Solanum nigrum, black nightshade, is a wild non-tuber bearing hexaploid species with a high level of resistance to Phytophthora infestans (Colon et al. 1993), the causal agent of potato late blight, the most devastating disease in potato production. However, the genetic mode of
resistance in S. nigrum is still poorly understood. In the present study, two S. nigrum accessions, 984750019 (N19) and #13, resistant (R) and susceptible (S), respectively, to three different isolates of P. infestans, were sexually crossed. The various kinds of progeny including F1, F2, F3, and backcross populations (BC1; F1 × S), as well as two populations produced by self-pollinating the R parent and S parent, were each screened for susceptibility
to P. infestans isolate MP 324 using detached leaf assays. Fifty seedling plant individuals of the F1 progeny were each resistant to this
specific isolate, similarly to the seedling plants resulting from self-pollination of the resistant R parent. Thirty seedling
plants obtained from self-pollination of the S parent were susceptible. Among a total of 180 F2 plants, the segregation ratio
between resistant and susceptible plants was approximately 3: 1. Among the 66 seedling plants of the BC1 progeny originating from crossing an F1 plant with the susceptible S parent, there were 26 susceptible and 40 resistant plants
to P. infestans. The segregation patterns obtained indicated monogenic dominant inheritance of resistance to P. infestans isolate MP 324 in S. nigrum acc. 984750019. This gene, conferring resistance to P. infestans, may be useful for the transformation of potato cultivars susceptible to late blight. 相似文献
4.
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
5.
Mathiyazhagan Kavino Sankarasubramanian Harish Neelakandan Kumar Duraisamy Saravanakumar Ramasamy Samiyappan 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(4):353-362
Pseudomonas fluorescens strains CHA0 and Pf1 were investigated for their biocontrol efficacy against Banana bunchy top virus (BBTV) in banana (Musa spp.) alone and in combination with chitin under glasshouse and field conditions. Bioformulation of P. fluorescens strain CHA0 with chitin was effective in reducing the banana bunchy top disease (BBTD) incidence in banana under glasshouse
and field conditions. In addition to disease control, the bioformulation increased the economic yield significantly compared
to the untreated control. Increased accumulation of oxidative enzymes, peroxidase (PO), polyphenol oxidase (PPO), phenylalanine
ammonia lyase (PAL), pathogenesis-related (PR) proteins, chitinase, β-1,3-glucanase and phenolics were observed in CHA0 bioformulation
amended with chitin-treated plants challenged with BBTV under glasshouse conditions. Indirect ELISA indicated the reduction
in viral antigen concentration in P. fluorescens strain CHA0 with chitin-treated banana plants corresponding to reduced disease ratings. The present study revealed that induction
of defence enzymes by P. fluorescens with chitin amendment reduced the BBTD incidence and increased bunch yield in banana. 相似文献
6.
Lian Wu Xie Shu Mei Jiang Hong Hui Zhu Wei Sun Yong Chang Ouyang Shi Kun Dai Xiang Li 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(4):571-578
Sclerotinia sclerotiorum is a worldwide ascomycete fungal plant pathogen, which causes enormous yield losses on major economic crops such as crucifers,
grain legumes and several other plant families. The objective of this research was to isolate and characterise some bioactive
products from cultures of fungi associated with the marine sponge Axinella sp. In total, nine fungal isolates were obtained from the marine sponge Axinella sp. collected from the South China Sea. A group of test strains, including two G+ strains (Bacillus subtilis and Staphylococcus aureus), two G− strains (Escherichia coli and Pseudomonas aeruginosa) and three fungi including two plant pathogenic fungi Sclerotinia sclerotiorum and Magnaporthe grisea and Saccharomyces cerevisiae, were employed as the indicator organisms for bioactivity screening. Using antagonistic tests and bioactive screening of
the ethyl acetate (EtOAc) extracts of the corresponding cultures, fungal isolate JS9 showed the stronger efficacy against
the test indicator strains, especially the indicator fungal pathogens. Isolate JS9 was further identified as Myrothecium sp. by a combination of morphological features and 18S rDNA BLAST on GenBank. Two macrocyclic trichothecenes, roridin A (compound
1) and roridin D (compound 2) were purified by tracking the activity of the EtOAc extract fractions and characterised with
spectral analyses including MS, 1H-NMR, 13C-NMR and disortionless enhancement by polarization transfer (DEPT). In vitro antifungal tests showed that the two macrocyclic trichothecenes were bioactive against S. cerevisiae, M. grisea and S. sclerotiorum with minimal inhibitory concentrations of 31.25, 125 and 31.25 μg ml−1 for roridin A, and 62.5, 250 and 31.25 μg ml−1 for roridin D, respectively. The present investigation demonstrated that two antifungal trichothecenes including roridin
A and roridin D produced by the fungus Myrothecium sp. isolated from the marine sponge Axinella sp. could be potential inhibitors against the plant pathogen S. sclerotiorum.
Lian Wu Xie and Shu Mei Jiang contributed equally to this work. 相似文献
7.
Xiaomei Guo Henrik U. Stotz 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(1):7-19
Oxalic acid is an essential virulence factor of Sclerotinia sclerotiorum that elicits wilting symptoms in infected host plants. Foliar wilting in response to oxalic acid is known to be dependent
on an increase in stomatal conductance. To determine whether stomatal regulation controls susceptibility to S. sclerotiorum, abscisic acid-insensitive and open stomata mutants of Arabidopsis thaliana were analyzed. Whereas abscisic acid-insensitive mutants were hypersusceptible to S. sclerotiorum, open stomata mutants were as susceptible as wild type. It was concluded that stomatal regulation does not control susceptibility
to S. sclerotiorum because open stomata mutants are known to only impair guard cells whereas abscisic acid-insensitive mutants also affect other
cell types. Guard cell-independent processes also control sensitivity to oxalic acid because oxalic acid was more toxic to
abscisic acid-insensitive mutants than to open stomata mutants. To explore a possible mechanism of toxicity, production of
reactive oxygen species was measured in plant cells after exposure to oxalic acid. Oxalic acid was found to elicit reactive
oxygen species production independently of abscisic acid. Nevertheless, cancellation of reactive oxygen species elicitation
after co-stimulation of wild-type guard cells with oxalic acid and abscisic acid provided evidence for antagonistic interaction
between both molecules. 相似文献
8.
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
9.
Severe spotting, blight and drop of leaves caused by Colletotrichum dematium were found on potted plants of Polygonatum falcatum, a liliaceous ornamental, in open fields in Kagawa Prefecture, Japan, in May 2001. This new disease was named anthracnose
of P. falcatum.
Keisuke Tomioka, Jouji Moriwaki, Toyozo Sato contributed equally to this work.
The fungal isolate and its nucleotide sequence data obtained in this study were deposited in Genebank, National Institute
of Agrobiological Sciences and the DDBJ/EMBL/GenBank databases under accessions MAFF239500 and AB334523, respectively. 相似文献
10.
Black rot, caused by Xanthomonas campestris pv. campestris, (Xcc), is one of the most serious diseases of crucifers world-wide. Forty-nine genotypes were evaluated for resistance under field
conditions in Tanzania after artificial inoculation with Xcc race 1. Open pollinated white cabbage cultivars were generally susceptible, while Portuguese and pointed cabbages exhibited
partial resistance. Some F1 white cabbage cultivars were highly susceptible, whereas others exhibited a high level of partial
resistance. The most promising of the hybrid cultivars were T-689 F1, Gianty F1, No. 9690 F1, N 66 F1, and SWR-02 F1. Breeding
line Badger I-16 exhibited the highest level of resistance of all genotypes. The genotypes accounted for 72.9–75.5% of the
variation of the disease severity when assessed on the leaves, and 71.4% of the variation when assessed as internal black
rot in heads at harvest. High correlations (equal to or above 0.7) were found between disease severities assessed on leaves
three times during the growing season and also with the amount of internal black rot in heads. Leaf loss also was correlated
with disease severity. The high genetic determination of the trait and the high correlations between disease assessments indicate
that selection for resistance to black rot will be efficient when field screenings are carried out. Evaluation of genotypes
for disease severity on leaves during the growing season combined with evaluations of head resistance in the most promising
genotypes may be a simple method to select resistant cultivars. 相似文献
11.
Margarita Lema María Elena Cartea Tamara Sotelo Pablo Velasco Pilar Soengas 《European journal of plant pathology / European Foundation for Plant Pathology》2012,133(1):159-169
Black rot, caused by Xanthomonas campestris pv. campestris (Xcc) is a severe seedborne disease of Brassica crops around the world. Nine races are recognized, being races 1 and 4 the
most aggressive and widespread. The identification of Xcc races affecting Brassica crops in a target area is necessary to
establish adequate control measures and breeding strategies. The objectives of this study were to isolate and identify Xcc
strains from northwestern Spain by using semi-selective medium and pathogenicity tests, determine the existing races of Xcc
in this area by differential series of Brassica spp., and evaluate the use of repetitive DNA polymerase chain reaction-based fingerprinting (rep-PCR) to differentiate among
the nine existing Xcc races. Seventy five isolates recovered from infected fields were identified as Xcc. Race-typing tests
determined the presence of the following seven pathogen races: 1, 4, 5, 6, 7, 8 and 9. Race 4 was the most frequent in Brassica oleracea and race 6 in Brassica rapa crops, therefore breeding should be focussed in obtaining resistant varieties to both races. Cluster analysis derived from
the combined fingerprints showed four groups, but no clear relationship to race, crop or geographical origin was found. Rep-PCR
analysis was found not to be a reliable method to discriminate among Xcc races, therefore race typing of Xcc isolates should
be done by using the differential series of Brassica spp. genotypes or another alternative approach. 相似文献
12.
Luigi Faino Paola Carli Antonino Testa Gennaro Cristinzio Luigi Frusciante Maria Raffaella Ercolano 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(2):233-241
Tomato is challenged by several pathogens which cause loss of production. One such pathogen is the oomycete Phytophthora infestans which is able to attack all the aerial parts of the plant. Although a wide range of resistance sources are available, genetic
control of this disease is not yet successful. Pyramiding R-genes through genetic transformation could be a straightforward
way to produce tomato and potato lines carrying durable resistance to P. infestans. In this work the R1 potato gene was transferred into tomato lines. The tomato transgenic lines were analyzed by using q-RT-PCR
and progeny segregation to determine the gene copy number. To test the hypothesis that R1 represents a specifically regulated R-gene, transgenic tomato plants were inoculated with P. infestans isolate 88133 and IPO. All the plants containing the R1 gene were resistant to the late blight isolate IPO-0 and susceptible to isolate 88133. These results provide evidence for
specific activation of the R1 gene during pathogen challenge. Furthermore, evidence for enhancement of PR-1 gene expression during P. infestans resistance response was obtained. 相似文献
13.
Organic management of soils is generally considered to reduce the incidence and severity of plant diseases caused by soil-borne
pathogens. In this study, take-all severity on roots of barley and wheat, caused by Gaeumannomyces graminis var. tritici, was significantly lower in organically-managed than in conventionally-managed soils. This effect was more pronounced on
roots of barley and wheat plants grown in a sandy soil compared to a loamy organically-managed soil. Fluorescent Pseudomonas spp. and in particular phlD+ pseudomonads, key factors in the take-all decline phenomenon, were represented at lower population densities in organically-managed
soils compared to conventionally-managed soils. Furthermore, organic management adversely affected the initial establishment
of introduced phlD+ P. fluorescens strain Pf32-gfp, but not its survival. In spite of its equal survival rate in organically- and conventionally-managed soils, the efficacy
of biocontrol of take-all disease by introduced strain Pf32-gfp was significantly stronger in conventionally-managed soils than in organically-managed soils. Collectively, these results
suggest that phlD+ Pseudomonas spp. do not play a critical role in the take-all suppressiveness of the soils included in this study. Consequently, the role
of more general mechanisms involved in take-all suppressiveness in the organically-managed soils was investigated. The higher
microbial activity found in the organically-managed sandy soil combined with the significantly lower take-all severity suggest
that microbial activity plays, at least in part, a role in the take-all suppressiveness in the organically-managed sandy soil.
The significantly different bacterial composition, determined by DGGE analysis, in organically-managed sandy soils compared
to the conventionally-managed sandy soils, point to a possible additional role of specific bacterial genera that limit the
growth or activity of the take-all pathogen. 相似文献
14.
Fusarium head blight in small grain cereals has emerged as a major problem in the Nordic countries. However, the impact of
this disease in oats has been less investigated than in other cereals. For this reason we have studied the infection process
(the optimal time of infection and infection pathways) of Fusarium graminearum in oats and its subsequent effects on kernel infection, deoxynivalenol (DON) content and germination capacity. In a field
experiment the oat cultivar Morton was spray-inoculated at different developmental stages, and the highest kernel infection
and DON content and lowest germination percentage were observed when inoculation took place at anthesis. Field grown oats
affected by a natural Fusarium head blight epidemic and spray-inoculated field and greenhouse oats were used to study the
infection pathway. Results showed that the fungus entered primarily through the floret apex into the floret cavity, where
it could infect via the internal surfaces of the palea, lemma and caryopsis. Both visual symptoms and fungal infections started at the apical
portions of the florets and progressed to the basal portions. Hyphae of F. graminearum grew more profusely on the anthers than on other floret parts during initial stages of infection. Disease development within
the oat panicle was slow and is primarily by physical contact between adjoining florets, indicating that the long pedicels
give Type II resistance in oats. 相似文献
15.
Mehdi Azadvar Virendra Kumar Baranwal D. K. Yadava 《Journal of General Plant Pathology》2011,77(3):194-200
Phyllody disease associated with 16SrIX phytoplasma was observed in the range of 4.1–11% in 10 different lines of toria [Brassica rapa L. subsp. dichotoma (Roxb.)] in experimental fields of the Indian Agricultural Research Institute, New Delhi, India during 2008 and 2009. The
toria phyllody (TP) phytoplasma was detected in all the symptomatic and 13.3% of asymptomatic toria plants by nested PCR.
The phytoplasma was detected in midrib, flower part, siliquae, stem, and root of infected plants as well as seeds. TP was
transmitted by grafting and by dodder to toria and nine other rapeseed/mustard species as confirmed by nested PCR. However,
symptoms of phytoplasma infection were induced only in toria, yellow sarson [Brassica
rapa L. subsp. trilocularis (Roxb.)], brown sarson [Brassica
rapa L. subsp. sarson (Prain)], rapeseed (B. napus subsp. oleifera), and rocket or taramira (Eruca sativa) but not in mustard (B. juncea), black mustard (B. nigra), Ethiopian mustard (B. carinata), B. tournefortii and white mustard (Sinapis alba). Transmission of TP phytoplasma to periwinkle (Catharanthus roseus) was successful only through dodder, but no transmission to tomato (Lycopersicon esculentum) or brinjal (Solanum melongena) was found. TP phytoplasma was detected in Laodelpax striatellus, an abundant planthopper in toria fields, which indicates that this planthopper may be a potential vector for TP phytoplasma. 相似文献
16.
Mohammad Reza Ojaghian 《Phytoparasitica》2011,39(2):185-193
Sixteen isolates belonging to 11 species of Trichoderma (T. asperellum, T. ceramicum, T. andinensis, T. orientalis, T. atroviride, T. viridescens, T. brevicompactum, T. harzianum, T. virens, T. koningii and T. koningiopsis) were evaluated for biological control of potato (Solanum tuberosum) stem rot caused by Sclerotinia sclerotiorum. In dual culture tests, all antagonists significantly reduced sclerotia formation, and were able to inhibit radial growth
of the pathogen. Growth inhibition by production of volatile and non-volatile inhibitors was also measured in in vitro tests. In screening the most efficient species of Trichoderma, establishment of mycelium on sclerotia and sclerotia lysis were also considered as important biocontrol qualities. Excluding
T. asperellum, T. brevicompactum, T. andinensis and T. harzianum, all tested Trichoderma species were able to lyse sclerotia. The sclerotia-destroying species of Trichoderma and one isolate of Talaromyces flavus were tested in greenhouse tests and during 2 years of field experimentation during the 2007 and 2008 cropping seasons. After
one aerial application of spore suspension in greenhouse trials, T. koningii, T. virens, T. ceramicum and T. viridescens were the most effective bio-agents and reduced significantly disease severity, and the least biocontrol efficacy was observed
in T. flavus. Under field conditions and after five soil and foliar applications of spore suspension, all tested antagonists reduced significantly
disease incidence. T. viridescens followed by T. ceramicum showed the best results. T. flavus and T. orientalis were less effective than other tested antagonists in both field trials. 相似文献
17.
Keisuke Tomioka Yuuri Hirooka Toshirou Nagai Hiroyuki Sawada Takayuki Aoki Toyozo Sato 《Journal of General Plant Pathology》2011,77(4):266-268
Severe blight of potted seedlings of monkshood caused by Plectosporium tabacinum was found in glasshouses in Kagawa Prefecture in southwest Japan in May 2001. Root rot and browning of stem bases were followed
by wilting and yellowing of leaves, then blighting of leaves, flower buds and stems. A fungus was isolated from diseased plants
and confirmed to cause the disease. The new disease was named “Plectosporium blight of monkshood”. 相似文献
18.
Hilal Ozkilinc Kamil Sarpkaya Sener Kurt Canan Can Hatice Polatbilek Aysegul Yasar Unal Sevinc Aysun Uysal Fatma Konukoglu 《Phytoparasitica》2017,45(5):719-728
Alternaria genus includes many plant pathogens on numerous hosts, causing leaf spots, rots and blights. Alternaria blight has been observed as one of the important fungal diseases of pistachio (Pistacia vera L.) as well as its wild relatives (P. terebinthus, P. lentiscus, P. khinjuk, P. atlantica, P. mutica) in Turkey. Alternaria species were sampled from Pistacia spp. hosts from different geographic regions in Turkey during field trips in late spring to early fall of 2013. Alternaria blight symptoms were observed mainly on fruits and rarely on leaves. Four hundred and twenty two of the isolates were morphologically defined as A. alternata, A. tenuissima, A. arborescens and also intermediate morpho-species between A. alternata/A. arborescens. Pathogenicity of the isolates was confirmed with host inoculations on detached fruits. Mating types of 270 isolates of Alternaria spp. from the collection were identified using a PCR-based mating type assay that amplifies either a MAT1-1 or a MAT1-2 fragment from the mating locus. Although a strongly clonal population structure was expected due to the putative asexual reproduction of these fungi, both idiomorphs were detected at equal frequencies at several different spatial scales. The distribution of mating types within each geographic region, within host species as well as in overall collection was not significantly different from 1:1. Amplified fragments of partial idiomorph sequences were obtained for representative isolates. Parsimony trees were depicted based on sequence data of mating type genes for these representative isolates as well as some other Alternaria species obtained by Genebank. Several point mutations presented a few clusters which are supported by high bootsrapped values. The Alternaria blight disease agents both from cultivated and wild hosts were pathogenic on pistachio which may cause difficulties to control the disease because of extensity of pathogen sources. Besides, equal mating type distribution of the pathogen at both geographic and host species levels suggests a potential for sexual reproduction of Alternaria spp. in Turkey. 相似文献
19.
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
20.
Dravya, a commercially developed aqueous seaweed extract, was evaluated for its effect on the expression of symptoms of bacterial
blight caused byXanthomonas campestris pv.malvacearum (E.F. Smith) Dye in cotton. Seed soaking with Dravya (1:500) followed by foliar spray thrice at intervals of 10 days (10,
20, 30 days after sowing) resulted in a reduction in blight incidence on plants by 66%, 70% and 74% as determined 40, 60 and
80 days, respectively, after sowing. Induction of systemic resistance was associated with increases in plant height, total
number of bolls formed, boll weight, stem girth, chlorophyll content, total phenols and peroxidase activity, which intimates
that Dravya could be used as an ecofriendly potential input in the integrated management of bacterial-blight of cotton. 相似文献