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1.
低毒病毒CHV1-CN280生防潜力的初步研究 总被引：1，自引：0，他引：1
前期研究表明,分离自中国的低毒病毒CHV1-CN280与其它多数低毒病毒相比具有更高的水平传播能力。本研究中,我们对CHV1-CN280的田间定殖能力及其它生防性状进行了评估。与其它两个模式低毒病毒相比,CHV1-CN280对栗疫菌Cryphonectria parasitica的毒力显著弱于典型的烈性低毒病毒CHV1-EP713,而更接近于典型的温和低毒病毒CHV1-Euro7。强致病性的栗疫菌感染CHV1-CN280后,成为典型的低毒菌株,不再对板栗植株造成严重危害,但是与感染典型烈性低毒病毒CHV1-EP713的菌株相比,寄主真菌在板栗枝条上仍保持了一定的定殖能力,其菌丝生长速率和分生孢子产量较高。初步的田间试验表明,在人工接种两年后,CHV1-CN280在田间成功定殖,并已扩散到田间自然存在的、与人为释放的低毒菌株不亲和的其它营养体亲合群的栗疫菌菌株中。结果表明,低毒病毒CHV1-CN280对栗疫病具有非常好的生物防治潜力。 相似文献
2.
Seçil Akıllı Çiğdem Ulubaş Serçe Yakup Zekai Katırcıoğlu Salih Maden Daniel Rigling 《European journal of plant pathology / European Foundation for Plant Pathology》2013,135(2):323-334
Chestnut blight caused by the introduced fungus Cryphonectria parasitica has been responsible for the decline of Castanea sativa in Turkey since the 1960s. In this study, 72 C. parasitica isolates were recovered from the Marmara and Black Sea regions of Turkey showing white or cream-coloured culture morphology and were subjected to various tests to determine if they were infected by Cryphonectria hypovirus 1 (CHV-1). The vast majority of the isolates (69 out of 72) were vc type EU-1. Both mating types were found among a subsample of the isolates. The hypovirus was detected in 55 isolates by dsRNA extraction and/or virus specific RT-PCR on total RNA extracts. All but one isolates showed no or only weak phenol oxidase activity on agar medium containing tannic acid, typical of CHV-1 infected isolates. Through sequencing of a specific region of the hypovirus genome, we found that 24 hypovirus isolates belonged to the CHV-1 subtype I and six to the CHV-1 subtype F2. The distribution of the two CHV-1 subtypes in Turkey showed a clear geographic pattern. CHV-1 subtype I was only detected in the Marmara and western Black Sea region, whereas subtype F2 was restricted to the eastern part of the Black Sea region. The effectiveness of 23 hypovirulent isolates was tested against a virulent isolate on 2–3 years old chestnut sprouts. Ten hypovirulent isolates, all infected by CHV-1 subtype I, prevented canker development by more than 80 % suggesting that they might be suitable for biological control of chestnut blight in Turkey. 相似文献
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4.
ABSTRACT In France, chestnut blight, caused by Cryphonectria parasitica, has been controlled since 1974 in orchards, but never in coppice forests, by releasing hypovirulent strains infected with CHV1 hypovirus. We tested the hypothesis that this biological control (BC) has lead to a decrease in blight severity, spread of hypovirulence, and change in C. parasitica populations. The low severity of chestnut blight was confirmed in the six regions studied (subdivided into zones). The remission of cankers was associated with the presence of white isolates presumed to be hypovirulent. These two parameters were also correlated, at the zonal level, to the frequency of sites where BC was used. However, the estimates of the natural background level of hypovirulence, independent of BC, ranged from 4% in forests in Dordogne to 60% in orchards in Lozère. Differences in the rate of hypovirulent isolates among regions were consistent with the diversity of vegetative compatibility (VC) types in populations of C. parasitica. The highest VC-type diversity and mean allelic diversity for known vegetative incompatibility (vic) genes were observed in Dordogne. We showed that the current diversity of VC types in populations of C. parasitica was lower than in 1981. We found 30 VC types among 1,113 isolates of C. parasitica. Ten VC types were incompatible with known EU testers, suggesting that one additional vic gene or allele at one of the six vic loci known should be present in Europe. 相似文献
5.
P. Zamora A. González Casas M. Dueñas R. San Martin J. J. Diez 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(1):65-73
Biological control with Cryphonectria hypovirus CHV1 of the chestnut blight, caused by the fungus Cryphonectria parasitica, has reduced the impact of the disease in Europe. The virus reduces the virulence of the fungus so that it causes non-lethal cankers, thus enabling the chestnut trees to overcome the disease. The virus can be transmitted horizontally by hyphal anastomosis or vertically to the conidia. In this study, we investigated growth and sporulation of the fungus as well as rates of horizontal transmission of the virus at different temperatures. We used fungal isolates of the vegetative compatibility types (vc types) that are most prevalent in Castilla and León (central northern Spain) to evaluate the effects of fungal strain on the parameters tested. In addition, we infected four isolates of C. parasitica with hypovirus subtypes CHV1-F1 and CHV1-I, to determine the influence of virus subtype on growth, sporulation and virus transfer. We assessed growth of fungal colonies and horizontal transmission of the virus at 15 °C and 25 °C. Colony growth was affected by an interaction between fungal isolates included in vc type EU1 or EU11 and virus at both 15 °C and 25 °C. However, horizontal transmission of the virus was only influenced by the fungal genotype of isolates included in vc type EU1 or EU11, and spore production was only affected by the virus subtype. Vertical transmission was also influenced by the fungal isolate and virus subtype. Growth of the fungal isolates varied depending on the virus subtype with which they were infected. This supports the theory that fungal host and virus subtype influence transmission and dissemination of hypovirulence. The fungal genotype affects colony growth and horizontal transmission of the virus. It is common to expect a good dissemination of the hypovirus with a low vc type diversity but the selection of the best combination of hypovirus and fungal isolate is crucial for the success of biological control not only for small areas but in larger chestnut populations as well. 相似文献
6.
Md. Iqbal Faruk Masatoshi Izumimoto Nobuhiro Suzuki 《Journal of General Plant Pathology》2008,74(6):425-433
The type virus of the family Hypoviridae,
Cryphonectria hypovirus 1 strain EP713 (CHV1-EP713), infects Cryphonectria parasitica, the filamentous causal fungus of chestnut blight, and reduces its virulence. This pathosystem serves as a model to study
fungus-mycovirus interactions. We previously developed a genetic screening protocol for host factors associated with symptom
induction by CHV1-EP713 and its mutants. In the procedure the standard field fungal isolate EP155 was transformed by cDNA
from a mild hypovirus mutant Cys(72), launching virus infection, and mutagenized by random plasmid insertion with pHygR conferring
hygromycin resistance. We now report an extension of the study to characterize different mutant strains, with different phenotypes
than their parental strain TCys(72)-1. TCys(72)-1 is moderately reduced in pigmentation and sporulation compared to the uninfected
wild-type strain EP155. Mutants sfb1, sfb2 and k202 were characterized biologically and molecularly in comparison to the previously
isolated mutant (namA) and the parental strain. These mutants harbored one (sfb1) or more copies (sfb2 and k202) of the mutagenic plasmid, pHygR.
The three mutants had similar biological attributes; that is, vegetative growth rate, conidiation and virulence (assay on
apples) was reduced on potato dextrose agar media, relative to the parental strain and pigmentation was the same or slightly
increased. Interestingly, viral dsRNA accumulation levels were apparently unaltered in these mutants. The screening method
was efficient for mining fungal mutants with unusual hypovirus symptoms. Further, characterization of the mutants provides
interesting insights into symptom induction by the hypovirus. 相似文献
7.
Kubisiak TL Hebard FV Nelson CD Zhang J Bernatzky R Huang H Anagnostakis SL Doudrick RL 《Phytopathology》1997,87(7):751-759
ABSTRACT A three-generation American chestnut x Chinese chestnut pedigree was used to construct a genetic linkage map for chestnut and to investigate the control of resistance to Endothia parasitica (chestnut blight fungus). DNA genotypes for 241 polymorphic markers (eight isozymes, 17 restriction fragment length polymorphisms [RFLPs], and 216 random amplified polymorphic DNAs [RAPDs]) were assayed on an F(2) family consisting of 102 individuals. Of these markers, 196 were segregating as expected and, subsequently, used for primary linkage mapping. Two isozymes, 12 RFLPs, and 170 RAPDs were mapped to 12 linkage groups spanning a total genetic distance of 530.1 Kosambi centimorgans. F(2) plants were evaluated for a response to E. parasitica infection by directly inoculating them with two unique fungal isolates and measuring canker expansion over a period of 3.5 months. Results were compared with the marker genotype data, thereby identifying genomic regions significantly associated with a resistance response. Single-marker or nonsimultaneous analyses of variance identified seven genomic regions that appear to have an effect on host response. Multiple-marker or simultaneous models suggest that three of these regions have a significant effect on host response, together explaining as much as 42.2% of the total variation for canker size. At each of the three putative resistance loci, alleles derived from the Chinese chestnut grandparent were associated with smaller canker size, or higher levels of resistance. 相似文献
8.
ABSTRACT Sustainable biological control of the chestnut blight fungus Crypho-nectria parasitica with hypovirulence depends on the production and dissemination of hypovirus-infected propagules of the pathogen. We investigated the ability of C. parasitica to sporulate and produce hypo-virus-infected spores on recently dead chestnut wood in coppice stands in southern Switzerland where hypovirulence has been naturally established. The number and type (active, inactive, or none) of cankers was assessed on experimentally cut and stacked stems, firewood stacks, and natural dead wood. Hypovirus-free and hypovirus-infected strains readily survived for more than 1 year in the chestnut blight cankers of the stacked stems. Sporulation of C. parasitica was observed on the surface of preexisting inactive and active cankers, as well as on newly colonized bark areas and was significantly more abundant than on comparable cankers on living stems. On all types of dead wood, we observed more stromata with perithecia than with pycnidia; however, a large proportion of the stromata was not differentiated. All perithecia examined yielded only hypovirus-free ascospores. The incidence of pycnidia that produced hypovirus-infected conidia ranged from 5% on natural dead wood to 41% on the experimental stacks. The mean virus transmission rate into conidia was 69%. Our study demonstrates a considerable saprophytic activity of C. parasitica on recently dead chestnut wood and supports the hypothesis of a role of this saprophytic phase in the epidemiology of hypovirulence. 相似文献
9.
N. Mahanti H. Bertrand C. Monteiro-Vitorello D. W. Fulbright 《Physiological and Molecular Plant Pathology》1993,42(6)
In Cryphonectria parasitica, the causal agent of chestnut blight, hypovirulence is commonly associated with the presence of cytoplasmically transmissible, double-stranded RNA (dsRNA). Recently, hypovirulent isolates of C. parasitica that do not have detectable levels of dsRNA have been obtained from healing cankers on chestnut trees. In these isolates, most of the respiratory activity is cyanide-resistant and salicylhydroxamate-sensitive, indicating that the mitochondrial alternative oxidase was induced. In contrast, the respiration of virulent isolates from the same trees and most of the dsRNA-containing hypovirulent isolates from a variety of geographical locations was cyanide sensitive. In all of these isolates, the alternative oxidase could be induced by growing them in the presence of chloramphenicol, an inhibitor of mitochondrial protein synthesis. The attenuated virulence and altered respiratory phenotypes could be transferred from the dsRNA-free hypovirulent isolates to virulent strains through hyphal anastomosis. Some of the dsRNA-free hypovirulent isolates grew more slowly than virulent strains. These results indicate that, in Cryphonectria, cytoplasmically transmitted hypovirulence may have more than one cause, and that mitochondrial mutations sometimes may be involved in the generation of this phenotype. 相似文献
10.
ABSTRACT The Cryphonectria parasitica populations in two 6-year-old European chestnut (Castanea sativa) coppices were investigated in southern Switzerland over a period of 4 years. Occurrence of white isolates indicating an infection with Cryphonectria hypovirus, vegetative compatibility groups (VCGs), hypovirulence conversion capacity, and mating types were used to characterize the populations. Sampling of randomly chosen cankers in the first year yielded 59% white isolates in one and 40% in the other population. The distribution of the VCGs and mating types was similar among white and orange isolates, indicating a homogeneous infection of the two populations by the hypovirus. Fourteen VCGs were found in the first population, 16 VCGs in the second. Altogether, 21 VCGs were determined. The same three VCGs dominated in both populations, comprising more than 60% of all isolates. Several VCGs were represented only by white isolates. Five of the six most common VCGs were clustered in two hypovirulence conversion groups, with almost 100% hypovirus transmission within each cluster. Repeated sampling of the same cankers in 1990, 1992, and 1994 did not reveal an increase of white isolates. The portion of blighted stems rose from 37% to about 60% in both plots within 4 years. In this time, chestnut blight killed 15% and competition an additional 21% of the sprouts. Predominantly, sprouts with low diameters at breast height were killed. The growth rate of new cankers was high in their first year and decreased gradually in the following years. A role of hypovirulence in the decline of disease severity was evident since (i) cankers yielding white isolates grew slower and killed considerably fewer sprouts than cankers with orange isolates; and (ii) the majority of the cankers yielded white isolates at least once during the 4-year observation period. 相似文献
11.
ABSTRACT Isolates of the chestnut blight fungus, Cryphonectria parasitica, were randomly sampled from 10 subpopulations in China and 8 subpopulations in Japan and screened for the presence of double-stranded (ds) RNA using an immunoblot procedure with a monoclonal antibody specific for dsRNA. The overall incidence of dsRNA in C. parasitica was 2 and 6% in China and Japan, respectively, much lower than the 28% found previously in North American populations. Genetic relatedness of dsRNAs within and among populations in China and Japan was examined using RNA-RNA hybridizations with labeled-dsRNA probes. The majority of Chinese and Japanese dsRNAs were members of a single hybridization group, related to Cryphonectria hypovirus 1 (CHV1) from Europe, and are referred to as CHV1-type dsRNAs. No evidence was obtained for genetic differentiation between CHV1-type dsRNAs sampled in China and Japan. Five Japanese isolates contained two genetically distinct dsRNAs. The larger segments (approximately 12 kilobases [kb]) were members of the CHV1 hybridization group, while the smaller segments (approximately 3 kb) did not hybridize with any known dsRNA from C. parasitica including the 2.7-kb dsRNA from isolate NB631 from New Jersey or dsRNA from isolate RC1 from Michigan. Two small dsRNA segments (approximately 1.8 and 2 kb) from one isolate sampled from Liaoning Province in northeastern China did not hybridize with any of the dsRNA probes tested including several described dsRNAs of similar size from C. parasitica in North America. Three dsRNAs from Anhui Province, China, hybridized to Cryphonectria hypovirus 2 (CHV2)-specific probes and are thus referred to as CHV2-type dsRNAs. Sequence analysis of 1,627 base pairs of these three CHV2-type dsRNAs from Anhui revealed that they were identical to each other in the region sequenced and very closely related to CHV2-NB58, isolated from New Jersey. We speculate that CHV2-NB58 may have been introduced into North America from this part of China. This is the first record of a North American C. parasitica dsRNA that is genetically related to a dsRNA from Asia. 相似文献
12.
ABSTRACT Twenty-one strains of Botrytis cinerea isolated from 13 species of plants grown in China were compared for pathogenicity on Brassica napus, mycelial growth on potato dextrose agar, and presence of double-stranded (ds)RNA. The results showed that the strain CanBc-1 was severely debilitated in pathogenicity and mycelial growth, compared with the 20 virulent strains. A dsRNA of approximately 3.0 kb in length was detected in CanBc-1 and 4 hypovirulent single-conidium (SC) isolates of CanBc-1, but was not detected in the 20 virulent strains of B. cinerea and 4 virulent SC isolates of CanBc-1. Results of the horizontal transmission experiment showed that the hypovirulent trait of CanBc-1 was transmissible and the 3.0-kb dsRNA was involved in the transmission of hypovirulence. Analysis of a 920-bp cDNA sequence generated from the 3.0-kb dsRNA of CanBc-1 indicated that the dsRNA element was a mycovirus, designated as B. cinerea debilitation-related virus (BcDRV). Further analyses showed that BcDRV is closely related to Ophiostoma mitovirus 3b infecting O. novo-ulmi, the causal agent of Dutch elm disease. Mitochondria and cytoplasm in hyphal cells of CanBc-1 became degenerated, compared with the virulent isolate CanBc-1c-66 of B cinerea. This is the first report on the occurrence of Mitovirus-associated hypovirulence in B. cinerea. 相似文献
13.
Diversity of Hypoviruses and Other Double-Stranded RNAs in Cryphonectria parasitica in North America
ABSTRACT Double-stranded (ds) RNAs in Cryphonectria parasitica were randomly sampled from nine subpopulations in North America using an antibody-based detection system for dsRNA. dsRNA was detected in 166 (28%) of a total of 595 C. parasitica isolates sampled by immunoblotting. Incidence of dsRNA infection within subpopulations ranged from 0% in samples from New Hampshire and Ontario to 100% in County Line, MI. Most of the dsRNAs sampled were approximately 9 to 13 kb in size. dsRNAs from 72 isolates analyzed by probing Northern blots with (32)P-labeled dsRNAs were in one of three hybridization groups. One hybridization group was widespread throughout eastern North America, being found in New York, New Jersey, Maryland, West Virginia, Kentucky, and Michigan. These dsRNAs hybridized to dsRNA from the previously described C. parasitica isolate SR2 from Maryland and are referred to as SR2-type dsRNAs. The second hybridization group was found almost exclusively in Michigan. The Michigan dsRNAs cross-hybridized to Cryphonectria hypovirus 3-GH2 (CHV3-GH2) and are referred to as CHV3-type dsRNAs.One dsRNA sampled from Kentucky hybridized to CHV3-type dsRNAs from Michigan. This dsRNA was probably derived from a fungal isolate that had been intentionally released for biological control at this same site 10 years previously and had become established in Kentucky. The third hybridization group was found only in New Jersey. These dsRNAs were much smaller than all other dsRNAs (3 and 5 kb) and were found in all 11 isolates that were probed; two of these isolates also had SR2-type dsRNA in mixed infections. None of the North American dsRNAs hybridized to CHV1 from Europe, even though CHV1 has been released in numerous locations in eastern North America for biological control of chestnut blight. Similarly, no dsRNAs hybridized to CHV2-NB58, a hypovirus found previously in New Jersey. Mixed infections of SR2-type and CHV3-type dsRNAs were found in 13 of 15 isolates from Frankfort, MI, while another nearby subpopulation (County Line) was infected with only CHV3-type dsRNAs. The distribution of dsRNA hybridization groups in C. parasitica thus presents a mixed picture, since one hybridization group is widespread, whereas two others are primarily restricted to smaller geographic areas. 相似文献
14.
棉花黄萎病菌菌株间交互保护作用的研究(1)两菌株有效间隔天数的试验 总被引：2，自引：0，他引：2
1983年和1984年,研究了棉株上接种黄萎病菌(Verticillium dahliae Kleb.)弱菌株对后继感染的强菌株所致病害的影响.接种弱菌株可减轻诱发的棉花黄萎病的病情.弱菌株与强菌株之间的接种间隔天数至关重要,以间隔5天接种,其交互保护作用最明显。 相似文献
15.
Chestnut blight has commonly been regarded as a phloem disease due to conspicuous stem cankers that result from infection by the fungal pathogen Cryphonectria (Endothia) parasitica. Stomatal conductance (gs), transpiration rate (E) and leaf water potential were measured throughout the day on leaves distal to naturally-occurring virulent (sunken bark with abundant stromata) or hypovirulent (swollen bark lacking stromata) cankers and cankers induced by inoculation with virulent or hypovirulent strains of C. parasitica. Relative to control stems, hydraulic conductivity (Kh), gs and E were reduced significantly (α = 0·05) for both natural virulent cankers, and cankers that were induced by a virulent strain. These effects were less pronounced for both natural and induced hypovirulent cankers. Isolation experiments revealed that the percentage of xylem tissue chips yielding C. parasitica was greater for virulent than for hypovirulent cankers. The data provide evidence that the localized presence of C. parasitica in cankers of American chestnut results in stomatal closure, possibly as a direct result of xylem dysfunction. 相似文献
16.
M. HALAMBEK 《EPPO Bulletin》1986,16(3):533-535
The present state of chestnut blight caused by the fungus Cryphonectria parasitica in Yugoslavia is presented. Canker disease is present all over the country wherever chestnut stands occur. Field observations have shown the presence of abnormal disease symptoms at some localities. Isolates of C. parasitica from these sites varied widely in cultural characteristics and pathogenic properties, some showing the characteristics of hypovirulent strains. 相似文献
17.
The vegetative compatibility of four hypovirulent isolates of Cryphonectria parasitica was checked with 35 virulent isolates obtained from chestnut samples collected in many regions of Italy. Artificial inoculation tests confirmed the effectiveness of a mixture prepared with hypovirulent isolates. This was packed in squeezing tubes, to simplify the biological control of chestnut blight in practice. 相似文献
18.
T. R. Gordon S. C. Kirkpatrick B. J. Aegerter D. L. Wood A. J. Storer 《Plant pathology》2006,55(2):231-237
For better characterization of the risk of pitch canker (caused by Gibberella circinata , anamorph = Fusarium circinatum ) to Douglas fir ( Pseudotsuga menziesii ), Californian isolates, selected exotic isolates, and ascospore progeny of a cross between wild-type Californian isolates were tested for aggressiveness to this host species. In addition, seedlings from representative provenances of P. menziesii in California were tested for susceptibility to pitch canker. The results revealed only minor differences between isolates, but differences in susceptibility between trees were often significant. The majority of the tested trees were relatively resistant as indicated by the development of only very short lesions, but some were clearly susceptible. 相似文献
19.
I. Papazova-Anakieva K. Sotirovski P. Cortesi M. G. Milgroom 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(1):35-42
Biological control of chestnut blight with hypovirulence depends on the successful transmission of hypoviruses between individuals
of the chestnut blight fungus, Cryphonectria parasitica. Vegetative incompatibility inhibits horizontal virus transmission, but not completely. In an effort to assess the potential
for the spread of hypoviruses in the Republic of Macedonia, we studied the transmission of Cryphonectria hypovirus 1 (CHV-1) among the five observed vegetative compatibility (vc) types of C. parasitica. One fungal isolate of each vc type was infected with CHV-1 and was paired in vitro with isolates of all other vc types for
a total of 20 combinations of virus donors and recipients, and 250 replicate trials per combination. Virus transmission was
scored after 7 days as successful if the recipient isolate took on an unpigmented culture phenotype typical of virus infection.
Transmission occurred at high frequencies between some pairs of vc types, but in <1% of the trials for 10 of the 20 combinations
of donors and recipients. Asymmetric transmission was observed between some vc types that had different alleles at vegetative
incompatibility loci vic1 or vic7; i.e., transmission occurred at high frequencies in one direction, but very low frequencies between the same pair of isolates
in the opposite direction. The expected virus transmission, calculated as the average transmission predicted for any two randomly
chosen individuals from a population, was highly negatively correlated to vc type diversity. Results for isolates of C. parasitica from Macedonia were similar to those from Italy, but less transmission was generally observed. Differences in genetic background
effects on transmission may vary among different populations even when isolates differ by the same vic alleles. 相似文献
20.
Koev G Mohan BR Dinesh-Kumar SP Torbert KA Somers DA Miller WA 《Phytopathology》1998,88(10):1013-1019
ABSTRACT Barley yellow dwarf viruses (BYDVs) are the most serious and widespread viruses of oats, barley, and wheat worldwide. Natural resistance is inadequate. Toward overcoming this limitation, we engineered virus-derived transgenic resistance in oat. Oat plants were transformed with the 5' half of the BYDV strain PAV genome, which includes the RNA-dependent RNA polymerase gene. In experiments on T2- and T3-generation plants descended from the same transformation event, all BYDV-inoculated plants containing the transgene showed disease symptoms initially, but recovered, flowered, and produced seed. In contrast, all but one of the BYDV-PAV-inoculated nontransgenic segregants died before reaching 25 cm in height. Although all of the recovered transgenic plants looked similar, the amount of virus and viral RNA ranged from substantial to undetectable levels. Thus, the transgene may act either by restricting virus accumulation or by a novel transgenic tolerance phenomenon. This work demonstrates a strategy for genetically stable transgenic resistance to BYDVs that should apply to all hosts of the virus. 相似文献