共查询到20条相似文献,搜索用时 578 毫秒
1.
Samuel M. Imathiu Rumiana V. Ray Matthew Back Martin C. Hare Simon G. Edwards 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(1):117-126
In vitro detached leaf assays involving artificial inoculation of wounded and unwounded oat and wheat leaves were used to investigate
the potential pathogenicity and aggressiveness of F. langsethiae, which was linked recently to the production of type A trichothecenes, HT-2 and T-2 in cereals in Europe. In the first two
experiments, two assays compared disease development by F. langsethiae with known fusarium head blight pathogen species each used as a composited inoculum (mixture of isolates) at 10°C and 20°C
and found all fungal species to be pathogenic to oat and wheat leaves in the wounded leaf assay. In the unwounded leaf assay,
F. langsethiae was not pathogenic to wheat leaves. Furthermore, there were highly significant differences in the aggressiveness of pathogens
as measured by lesion length (P < 0.001). In the second two experiments, pathogenicity of individual F. langsethiae isolates previously used in the composite inoculum was investigated on three oat and three wheat varieties. The wounded leaf
assay showed that all isolates were pathogenic to all oat and wheat varieties but only pathogenic towards oat varieties in
the unwounded assay. Highly significant differences (P < 0.001) in lesion length were found between cereal varieties as well as between isolates in the wounded assay. Significant
differences in lesion lengths (P = 0.014) were also observed between isolates in the unwounded assay. Results from the detached leaf assays suggest that F. langsethiae is a pathogen of wheat and oats and may have developed some host preference towards oats. 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.
Roghayeh Hemmati Mohammad Javan-Nikkhah Celeste C. Linde 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(4):617-628
The genetic structure of 276 Sclerotinia sclerotiorum isolates representing 37 field populations from four provinces in northern Iran were analysed with six polymorphic microsatellite
loci. In total, 80 haplotypes were detected with 19 haplotypes (23.7%) shared amongst at least two regional populations. None
of the haplotypes were shared among all four regional populations. Of the 80 haplotypes, 32 haplotypes (40%) occurred in low
frequencies represented by only one isolate. Moderate levels of gene diversity (H = 0.51 to 0.61) and genotypic diversity (Ĝ = 12.0 to 22.0; clonal fraction = 0.39 to 0.67) for regional populations were observed. Genotypic diversities (Ĝ) did not differ significantly among populations. All regional populations were in linkage equilibrium indicating the occurrence
of outcrossing. Low to moderate levels of population subdivision (0.03 to 0.07), were observed among regional populations.
Only one large panmictic population was inferred by Structure, indicating no significant population structure. A Mantel test showed no significant isolation by distance (r = −0.43; P = 0.18), indicating anthropogenic movement of inoculum. The results demonstrated that S. sclerotiorum populations in northern Iran, are randomly mating and have a number of shared haplotypes among regional populations; this
possibly represents recent founder populations and/or a high occurrence of anthropogenic migration of infected plant material
among populations. 相似文献
4.
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
5.
Khalid A. Hussein Mohamed A. A. Abdel-Rahman Ahmed Y. Abdel-Mallek Saad S. El-Maraghy Jin Ho Joo 《Phytoparasitica》2012,40(2):117-126
The greater wax moth Galleria mellonella L. (Lepidoptera: Pyralidae) is occasionally found in beehives and is a major pest of stored wax. Entomopathogenic fungi have
recently received attention as possible biocontrol elements for certain insect pests. In this study, 90 isolates of Beauveria bassiana and 15 isolates of Metarhizium anisopliae were screened for proteases and lipases production. The results showed significant variations in the enzymatic action between
the isolates. In the bioassay, the selected isolates evinced high virulence against the 4th instar of the G. mellonella larvae. The isolates BbaAUMC3076, BbaAUMC3263 and ManAUMC3085 realized 100% mortality at concentrations of 5.5 × 106 conidia ml−1, 5.86 × 105 conidia ml−1, and 4.8 × 106 conidia ml−1, respectively. Strong enzymatic activities in vitro did not necessarily indicate high virulence against the tested insect pest. The cuticle of the infected larvae became dark
and black-spotted, indicating direct attack of fungus on the defense system of the insects. The LC50 values were 1.43 × 103, 1.04 × 105 and 5.06 × 104 for Bba3263AUMC, Bba3076AUMC and Man3085AUMC, respectively, and their slopes were determined by computerized probit analysis
program as 0.738 ± 0.008, 0.635 ± 0.007 and 1.120 ± 0.024, respectively. 相似文献
6.
B. Wang C. L. Brubaker P. H. Thrall J. J. Burdon 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(4):541-551
Temporal variation in Fusarium oxysporum f. sp. vasinfectum (Fov) populations was determined by comparing the genetic diversity of pathogen isolates recovered from three consecutive cotton
crops (2002, 2004 and 2006) in the Boggabilla area of New South Wales, Australia. A total of 288 isolates were collected,
among which 25 distinct AFLP genotypes were identified. These genotypes were classified into two main groups corresponding
to known vegetative compatibility groups (VCG)—01111 and 01112. The Fov populations were dominated by four genotypes (I-A, I-B, II-A, II-B) that accounted for 87.5% of the isolates. Significant
temporal variation was observed in both sampled fields with 6.8% and 10.7% of total genetic variation being attributed to
differences among collections in different years. Genetic diversity based on Nei’s gene diversity and the Shannon-Wiener index
increased over time. Significant changes in the frequency of the dominant Fov genotypes were observed in one field, where genotype I-A declined from 84.8% to 40.0% over the study period (2002–2006),
while genotype I-B increased from 7.6% to 35.4%. Strong inter-genotype competition was detected in glasshouse bioassays with
93.4% of symptomatic plants sampled from dual inoculation trials being infected by single genotypes. Competition was differentially
mediated by cotton cultivars as the competitive ability of pathogen genotype I-B was enhanced on the resistant cultivar Sicot
189 relative to the susceptible cultivar Siokra 1–4. This suggests that host-mediated inter-genotype competition may play
an important role in temporal variation in Fov populations in the field. 相似文献
7.
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
8.
Ricardo B. Baldassari Ester Wickert Antonio de Goes 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(2):103-110
In the present study, the pathogenicity of 36 isolates of Guignardia species isolated from asymptomatic ‘Tahiti’ acid lime fruit peels and leaves, ‘Pêra-Rio’ sweet orange leaves and fruit peel
lesions, and a banana leaf were characterized. For pathogenicity testing, discs of citrus leaves colonized by Phyllosticta citricarpa under controlled laboratory conditions were kept in contact with the peels of fruit that were in susceptible states. In addition,
pathogenicity was related to morphological characteristics of colonies on oatmeal (OA) and potato dextrose agar (PDA). This
allowed the morphological differentiation between G. citricarpa and G. mangiferae. Polymerase chain reactions (PCRs) were also used to identify non-pathogenic isolates based on primers specific to G. citricarpa. A total of 14 pathogenic isolates were detected during pathogenicity tests. Five of these were obtained from leaf and fruit
tissues of the ‘Tahiti’, which until this time had been considered resistant to the pathogen. Given that the G. citricarpa obtained from this host was pathogenic, it would be more appropriate to use the term insensitive rather than resistant to
categorize G. citricarpa. A non-pathogenic isolate was obtained from lesions characteristic of citrus black spot (CBS), indicating that isolation
of Guignardia spp. under these conditions does not necessarily imply isolation of pathogenic strains. This also applied to Guignardia spp. isolates from asymptomatic citrus tissues. Using fluorescent amplified fragment length polymorphism (fAFLP) markers,
typically pathogenic isolates were shown to be more closely related to one another than to the non-pathogenic forms, indicating
that the non-pathogenic isolates display higher levels of genetic diversity. 相似文献
9.
Fusarium wilt is an economically important fungal disease of common eggplant (Solanum melongena) cultivated in the eastern Mediterranean region of Turkey. Seventy-four isolates of Fusarium oxysporum isolated from diseased eggplant displaying typical Fusarium wilt symptoms were screened for pathogenicity on the highly susceptible
cv. ‘Pala’. All the isolates tested were pathogenic to eggplant and designated as Fusarium oxysporum f. sp. melongenae (Fomg). Genetic diversity among a core set of 20 Fomg isolates that were selected based upon geographic locations, were characterized by using pathogenicity, vegetative compatibility
grouping (VCG), and random amplified polymorphic DNA (RAPD) analysis. The area under the disease progress curve (AUDPC) was
calculated for each Fomg isolate until 21 days after inoculation (DAI). The most virulent isolate was identified as Fomg10 based on AUDPC, disease severity and vascular discoloration measurements at 21 DAI. At this date, a good correlation was
observed between disease severity and AUDPC values for all isolates (r = 0.73). UPGMA (unweighted pair group method with arithmetic average) cluster analysis of RAPD data using Dice’s coefficient
of similarity differentiated all the Fomg isolates tested, and indicated considerable genetic variation among Fomg isolates, but isolates from the same geographic region were grouped together. There was no direct correlation between clustering
in the RAPD dendrogram and pathogenicity testing of Fomg isolates. Twenty isolates of Fomg were assigned to VCG 0320. 相似文献
10.
The apple rust mite Aculus schlechtendali (Nal.) (Acari: Eriophyidae), is a main pest in apple-growing areas in Ankara, Turkey, and chemical control applications have
some limitations. Entomopathogenic fungi have a potential for biological control of mites. In this study, an entomopathogenic
fungus, Paecilomyces lilacinus (Thom) Samson (Deuteromycota: Hyphomycetes), was first isolated from the mite cadavers on Japanese crab apple leaves and
pathogenicity of the fungus was observed in different inoculum densities and relative humidities. The pathogen caused up to
98.22% mortality of the mite population. The effects of some fungicides on the entomopathogenic fungus were determined in
in vitro studies. Carbendazim, penconazole and tebuconazole were the most effective fungicides on mycelial growth of P. lilacinus, with EC50 values under 3 μg ml−1. In spore germination tests, captan, mancozeb, propineb were the most effective fungicides, followed by tebuconazole, penconazole,
nuarimol and chlorothalonil. Sulphur could not inhibit the conidia germination totally at 5,000 μg ml−1. Copper oxychloride and fosetyl-al prevented conidia formation at concentrations above 1,000 μg ml−1. 相似文献
11.
Matthew P. Daugherty Joao R. S. Lopes Rodrigo P. P. Almeida 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(3):333-340
Differences in the virulence of a pathogen among host species can occur because hosts differ in their resistance or tolerance
to infection or because of underlying genetic variation in the pathogen. The xylem-limited bacterium Xylella fastidiosa is pathogenic to dozens of plant species throughout the Americas, and is structured into genetically and biologically distinct
strains. In some plants X. fastidiosa causes striking leaf scorch symptoms and in others, such as alfalfa, stunting is the primary symptom. The mechanism by which
these symptoms occur has been debated. We tested the hypothesis that symptoms result from X. fastidiosa-induced water stress, and that the magnitude of water stress is strain-dependent. We mechanically inoculated alfalfa plants
with one of 14 isolates (5 identified genetically as “almond” and 9 as “grape” isolates), and compared stable carbon isotope
ratios among isolates. Infected plants showed significant isotopic shifts (up to 2% on average) relative to healthy plants
that were consistent with water stress. Moreover, there were significant differences in water stress among isolates, with
a tendency for grape isolates to cause more severe water stress than almond isolates. There was also a positive relationship
between plant infection level and isotopic shift (slope ± SE = 0.273 ± 0.068), which supports the hypothesis that X. fastidiosa symptoms result from bacterial multiplication and vessel occlusion. Unexpectedly, however, water stress was not correlated
with measures of alfalfa stunting. These results suggest X. fastidiosa induces strain-specific levels of water stress, but factors other than water stress alone are responsible for stunting. 相似文献
12.
Daniela Minerdi Marino Moretti Yuan Li Laura Gaggero Angelo Garibaldi Maria Lodovica Gullino 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(2):227-237
A conventional PCR and a SYBR Green real-time PCR assays for the detection and quantification of Phytophthora cryptogea, an economically important pathogen, have been developed and tested. A conventional primer set (Cryp1 and Cryp2) was designed
from the Ypt1 gene of P. cryptogea. A 369 bp product was amplified on DNA from 17 isolates of P. cryptogea. No product was amplified on DNA from 34 other Phytophthora spp., water moulds, true fungi and bacteria. In addition, Cryp1/Cryp2 primers were successfully adapted to real-time PCR.
The conventional PCR and real-time PCR assays were compared. The PCR was able to detect the pathogen on naturally infected
gerbera plants and on symptomatic artificially infected plants collected 21 days after pathogen inoculation. The detection
limit was 5 × 103
P. cryptogea zoospores and 16 fg of DNA. Real-time PCR showed a detection limit 100 times lower (50 zoospores, 160 ag of DNA) and the
possibility of detecting the pathogen in symptomless artificially infected plants and in the re-circulating nutrient solution
of closed soilless cultivation systems. 相似文献
13.
Baidya N. Mahto Suraj Gurung Achala Nepal Tika B. Adhikari 《European journal of plant pathology / European Foundation for Plant Pathology》2012,133(2):405-417
Spot blotch, caused by Cochliobolus sativus (Ito & Kuribayashi) Drechs. ex Dastur, is one of the important diseases of wheat worldwide. The main objective of this study
was to investigate the phenotypic and genotypic variability among C. sativus isolates from the hills and plains in Nepal. A total of 48 monoconidial isolates of C. sativus from the hills (n = 24 isolates) and plains (n = 24 isolates) in Nepal were analyzed for morphology, aggressiveness and genetic structure. C. sativus isolates were grouped into three categories on the basis of their colony texture and mycelia colour. Thirteen isolates from
the hills and plains belonging to three morphological groups were randomly selected and evaluated for aggressiveness on eight
wheat cultivars (Chirya 1, Chirya 7, Milan/Shanghai 7, SW 89–5422, PBW 343, BL 1473, BL 3036, and RR 21) at the seedling stage.
Nonparametric analysis revealed that the isolates from the plains (median disease rating of 5) were significantly (P = 0.0001) more aggressive than the isolates from the hills (median disease rating of 3). A significant (P = 0.0001) isolate by cultivar interaction was demonstrated and the isolates from the same geographic region and morphological
group displayed different degrees of aggressiveness on wheat cultivars tested. Combined IS-PCR and rep-PCR analyses revealed
moderate gene diversity (H = 0.24 and 0.25 for the hills and plains, respectively). Low linkage disequilibrium (LD) value and non-significant (P = 0.001) population differentiation (G″ST = 0.05) were detected, indicating that isolates of C. sativus from the hills and plains in Nepal were genetically similar. Analysis of molecular variation (AMOVA) revealed low (7%) levels
of genetic variation between the hill and plain populations, whereas >93% of genetic variation was found within populations.
Overall, C. sativus isolates from Nepal are pathologically and genetically diverse, and such information will be useful in developing wheat cultivars
resistant to C. sativus. 相似文献
14.
Y. L. Wu G. J. Yi X. X. Peng 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(3):409-415
In order to accelerate breeding and selection for disease resistance to Fusarium wilt, it is important to develop bioassays
which can differentiate between resistant and susceptible cultivars efficiently. Currently, the most commonly used early bioassay
for screening Musa genotypes against Fusarium oxysporum f. sp. cubense (Foc) is a pot system, followed by a hydroponic system. This paper investigated the utility of in vitro inoculation of rooted banana plantlets grown on modified medium as a reliable and rapid bioassay for resistance to Foc. Using a scale of 0 to 6 for disease severity measurement, the mean final disease severities of cultivars expressing different
levels of disease reaction were significantly different (P ≤ 0.05). Twenty-four days after inoculation with Foc tropical race 4 at 106 conidia ml−1, the plantlets of two susceptible cultivars had higher final disease severities than that of four resistant cultivars. Compared
with ‘Guangfen No.1’, ‘Brazil Xiangjiao’ is highly susceptible to tropical race 4 and its mean final disease severity was
the highest (5.27). The plantlets of moderately resistant cultivar ‘Formosana’ had a mean final disease severity (3.53) lower
than that of ‘Guangfen No.1’ (4.33) but higher than that of resistant cultivars: ‘Nongke No.1’, GCTCV-119, and ‘Dongguan Dajiao’
(1.87, 1.73, and1.53, respectively). Promising resistant clones acquired through non-conventional breeding techniques such
as in vitro selection, genetic transformation, and protoplast fusion could be screened by the in vitro bioassay directly. Since there is no acclimatization stage for plantlets used in the bioassay, it helps to improve banana
breeding efficiency. 相似文献
15.
You-Xiu Zheng Bing-Nan Shen Ching-Chung Chen Fuh-Jyh Jan 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(1):1-5
A new disorder exhibiting flower crinkle on Phalaenopsis orchids bearing white flowers has been observed in Taiwan, China and Japan for several years. This disorder decreased the
flower longevity and was considered as a physiological syndrome. The objective of this study was to identify and characterize
the real causal agent of this new Phalaenopsis disorder. Five plants of Phalaenopsis hybrids “V3” (Phal. Yukimai × Phal. Taisuco Kochdian) with flower crinkle symptoms were collected and tested by enzyme-linked
immunosorbent assay with antisera against 18 viruses. The extract of leaves and flowers from one diseased plant (96-Ph-16)
reacted positively only to antiserum against Odontoglossum ringspot virus (ORSV), while those from the other four plants (96-Ph-7, 96-Ph-17, 96-Ph-18 and 96-Ph-19) reacted positively to the antisera
against ORSV and Cymbidium mosaic virus (CymMV). Five ORSV isolates, one each from flowers of those five diseased Phalaenopsis orchids, were established in Chenopodium quinoa. A CymMV culture was isolated from the flowers of one of the ORSV/CymMV mix-infected Phalaenopsis orchids (96-Ph-19). To determine the causal agent of the flower crinkle disease, healthy Phalaenopsis seedlings were singly or doubly inoculated with the isolated ORSV and/or CymMV. Results of back inoculation indicated that
ORSV is the sole causal agent of the crinkle symptom on petals of Phalaenopsis orchid. The CP gene of the ORSV isolates from this study shared 97.3–100% nucleotide identity and 96.2–100% amino acid identity
with those of 41 ORSV isolates available in GenBank. This is the first report demonstrating ORSV as the sole virus causing
flower crinkle disease on Phalaenopsis orchids. 相似文献
16.
T. Miedaner C. Bolduan A. E. Melchinger 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(1):113-123
Fusarium graminearum and F. verticillioides are among the most important pathogens causing ear rot of maize in Central Europe. Our objectives were to (1) compare eight
isolates of each species on two susceptible inbred lines for their variation in ear rot rating and mycotoxin production across
3 years, and (2) analyse two susceptible and three resistant inbred lines for potential isolate x line interactions across
2 years by silk-channel inoculation. Ear rot rating, zearalenone (ZEA) and deoxynivalenol (DON) concentrations were evaluated
for all F. graminearum isolates. In addition, nivalenol (NIV) concentrations were analysed for two NIV producers. Fumonisin (FUM) concentrations
were measured for all F. verticillioides isolates. Mean ear rot severity was highest for DON producers of F. graminearum (62.9% of the ear covered by mycelium), followed by NIV producers of the same species (24.2%) and lowest for F. verticillioides isolates (9.8%). For the latter species, ear rot severities differed highly among years (2006: 24%, 2007: 3%, 2008: 7%). Mycotoxin concentrations among isolates showed
a broad range (DON: 100–284 mg kg−1, NIV: 15–38 mg kg−1, ZEA: 1.1–49.5 mg kg−1, FUM: 14.5–57.5 mg kg−1). Genotypic variances were significant for isolates and inbred lines in all traits and for both species. Isolate x line interactions
were significant only for ear rot rating (P < 0.01) and DON concentration (P < 0.05) of the F. graminearum isolates, but no rank reversals occurred. Most isolates were capable of differentiating the susceptible from the resistant
lines for ear rot severity. For resistance screening, a sufficiently aggressive isolate should be used to warrant maximal
differentiation among inbred lines. With respect to F. verticillioides infections, high FUM concentrations were found in grains from ears with minimal disease symptoms. 相似文献
17.
Ninghai Lu Jianfeng Wang Xianming Chen Gangming Zhan Changqing Chen Lili Huang Zhensheng Kang 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(4):685-693
In China, wheat stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most destructive diseases of wheat. The Longnan and Linxia regions in Gansu Province and Qinghai Province
are the major over-summering regions for the pathogen and key epidemiological zones in Northwest China. Population genetic
diversity and interregional long-distance spread of the wheat stripe rust pathogen in Northwest China were studied using SSR
markers. The genetic diversity in the Longnan population was much higher than those in the Linxia and Qinghai populations.
Therefore, the molecular data confirmed that the Longnan region is a center of genetic diversity for P. striiformis f. sp. tritici in Northwest China. The low genetic differentiation (Gst = 0.15) and the extensive gene flow (Nm = 1.37) were found among the three regions in Northwest China. The most important conclusion of this study is that the stripe
rust inoculum in Qinghai can come from both Longnan and Linxia, but mainly from Longnan directly in the spring. 相似文献
18.
Erika Valéria Saliba Albuquerque Poliene Martins Costa Ana Cristina Meneses Mendes Gomes Marcilene Santos Antonio Alves Pereira Michel Nicole Diana Fernandez Maria Fatima Grossi-de-Sa 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(3):365-373
Root-knot nematodes (RKN) are obligate parasite species of the genus Meloidogyne that cause great losses in Arabica coffee (Coffea arabica L.) plantations. Identification of resistant genotypes would facilitate the improvement of coffee varieties aiming at an
environmental friendly and costless nematode control. In this work, the C. arabica genotype ‘UFV 408-28’ was found to be resistant to the most destructive RKN species M. incognita. Pathogenicity assays indicated that the highly aggressive populations of M. incognita races 1, 2 and 3 were not able to successfully reproduce on ‘UFV 408-28’ roots and displayed a low gall index (GI = 2). An
average reduction of 87% reduction of the M. incognita population was observed on ‘UFV 408-28’ when compared to the susceptible cultivar ‘IAC 15’. By contrast, ‘UFV 408-28’ was
susceptible to the related species M. exigua and M. paranaensis (GI = 5 and 4, respectively). Histological observations performed on sections of UFV408-28 roots infected with M. incognita race 1 showed that nematode infection could be blocked right after penetration or during migration and establishment stages,
at 6 days, 7 days and 8 days after infection (DAI). Fluorescence and bright field microscopy observations showed that root
cells surrounding the nematodes exhibited HR-like features such as accumulation of phenolic compounds and a necrotic cell
aspect. In the susceptible ‘IAC 15’ roots, 6 DAI, feeding sites contained giant cells with a dense cytoplasm. Necrotic cells
were never observed throughout the entire infection cycle. The HR-like phenotype observed in the ‘UFV 408-28’—M. incognita interaction suggests that the coffee resistance may be mediated by a R-gene based immunity system and may therefore provide new insights for understanding the molecular basis of RKN resistance
in perennial crops. 相似文献
19.
Phap Q. Trinh Wim M. L. Wesemael Sy T. T. Nguyen Chau N. Nguyen Maurice Moens 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(1):45-57
The pathogenicity and reproductive fitness of Pratylenchus coffeae and Radopholus arabocoffeae from Vietnam on coffee (Coffea arabica) seedlings cv. Catimor were evaluated in greenhouse experiments. The effect of initial population densities (Pi = 0, 1, 2,
4, 8, 16, 32, 64, 128, and 256 nematodes per cm3 soil) was studied for both species at different days after inoculation (dai). The data were adjusted to the Seinhorst damage
model Y = m + (1-m).zPi-T. Tolerance limit (T) for P. coffeae was zero for the height and the diameter of the coffee plants. For the diameter, the T-value for R. arabocoffeae was 25.6 for 30 and 60 dai and 12.8 for 90 and 120 dai. After 4 months T was zero. The low tolerance limits indicate that
Arabica coffee is highly intolerant to both nematode species. At the end of the experiment (180 dai), all plants were infected
and most were dead when inoculated with R. arabocoffeae at initial densities of 32, 64, 128 and 256 nematodes/cm3 soil. For P. coffeae plant death was already observed at the lowest inoculation densities. Growth of coffee was reduced at all inoculation levels
for both species. Pratylenchus coffeae and R. arabocoffeae caused intense darkening of the roots, leaf chlorosis and a strong reduction of root and shoot growth. It was observed that
P. coffeae mainly destroyed lateral roots rather than tap roots, whereas R. arabocoffeae reduced tap root length rather than the lateral roots. At the lowest inoculum densities, the reproduction factor of P. coffeae was 2.38 and 2.01 for R. arabocoffeae, indicating that arabica coffee is a host for both species. Plant growth as expressed by shoot height and shoot and root
weight measured 60 dai was negatively correlated with nematode (both species) density as expressed by the geometric mean of
nematode numbers at 30 and 60 dai. 相似文献
20.
W. Purahong D. Alkadri P. Nipoti A. Pisi M. Lemmens A. Prodi 《European journal of plant pathology / European Foundation for Plant Pathology》2012,132(3):381-391
Fusarium graminearum is a common agent causing Fusarium head blight (FHB) on wheat throughout the world. Aggressiveness is crucial for understanding
the interaction between host-pathogen in the FHB-wheat system. In this paper, we modified and validated the Petri-dish test
originally described by Mesterhazy (Phytopathologische Zeitschrift 93:12–25, 1978) to quantify the aggressiveness of 25 F. graminearum strains using four durum wheat cultivars with different resistance levels for FHB. The results were highly significant and
correlated with those obtained using adult plants in the growth chamber and in the field (r = 0.94, P < 0.001 and r = 0.65, P < 0.001, respectively). The Petri-dish test was further investigated for its repeatability and stability in different durum
wheat cultivars and highly significant correlation coefficients were obtained (r = 0.90–0.91 (P < 0.001), 0.89–0.95 (P < 0.001), respectively). In this study, we also demonstrated that germination rate reduction and coleoptile length reduction
are parameters involved with aggressiveness of F. graminearum. The mean of three disease parameters from the modified Petri-dish method is introduced in this paper as a new parameter
for aggressiveness and named “Petri-dish aggressiveness index”. The results obtained reveal that this modified Petri-dish
test is rapid, reliable and stable with different durum wheat cultivars, and yields highly significant correlation coefficients
with floret and ear inoculations, thus it is suitable to be used for quantification of aggressiveness of F. graminearum. 相似文献