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1.
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
2.
The major chestnut-growing areas in Aydın Province, which yield nearly 35% of Turkey’s production, were examined for the presence
of chestnut blight and bark samples were collected from the canker formations. Generally virulent type cankers were observed.
Of 31 villages, 22 were found to be contaminated with the disease. A total of 97Cryphonectria parasitica (Murrill) M.E. Barr. isolates were characterized for the presence of potential hypovirulence by looking at cultural characteristics
on media and virulence in cv. ‘Golden Delicious’ apple fruit. The isolates were placed into four groups based on pigmentation
and abundance of pycnidia formation. Isolates produced lesions of various sizes on apple fruits but lesion size was not correlated
with cultural characteristics typical to hypovirulent isolates. Among 97 isolates, ten possessing the characteristics associated
with hypovirulence were assayed for the presence of dsRNA. Among these isolates only one, coded M1-3, was found to contain
dsRNA. No dsRNA was detected in the single conidium isolates derived from M1-3. All of the isolates were screened for vegetative
compatibility and two European vc types, EU-1 and EU-12, were detected. This low vc-type diversity in the region may indicate
a high potential for spread of transmissible hypovirulence.
http://www.phytoparasitica.org posting May 30, 2008. 相似文献
3.
核盘菌中dsRNA种类及其与致病力的关系 总被引：2，自引：0，他引：2
对源于我国黑龙江省佳木斯市同一块茄子田的14个核盘菌(Sclerotinia sclerotiorum)菌株及其中1个菌株Ep-1PNA5的2个衍生菌株的致病力和菌丝中的双链RNA(dsRNA)进行了分析。在马铃薯琼脂培养基(PDA)上对5个弱致病型核盘菌菌株(Ep-1PD、Ep-1PI、Ep-1PL、Ep-1PM、Ep-1PN)异常性状(菌丝生长慢,且异常分枝)的传染特性进行了测定。结果表明:在离体油菜叶片上,16个供试核盘菌菌株中,7个属于强致病类型,7个属于弱致病类型,2个属于中等致病类型。从10个核盘菌菌株的菌丝中检测到dsRNA因子,并可分成3类dsRNA电泳谱型。第一类dsRNA谱型只含有7.4kb大小的dsRNA分子,3个强致病型核盘菌菌株属于这种谱型;第二类dsRNA谱型含有2种dsRNA分子,大小分别为6.4kb和7.4kb。6个弱致病型菌株属于这种谱型;第三类dsRNA谱型只含有6.4kb大小的dsRNA分子。1个弱致病类型菌株属于这种谱型。从另外6个核盘菌菌株的菌丝中没有检测到任何dsRNA因子,其中4个菌株属于强致病型菌株,2个菌株属于中等致病型。可见,6.4kb大小的dsRNA因子与核盘菌弱致病性状密切相关。5个弱致病型核盘菌菌株(Ep-1PD、Ep-1PI、Ep-1PL、Ep-1PM、Ep-1PN)的异常性状可以通过菌丝接触传染给一些强致病型核盘菌菌株,使其菌丝生长变慢及分枝异常。结果还表明:这些弱致病型核盘菌异常性状的传染具有菌株特异性。 相似文献
4.
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
5.
ABSTRACT Two genetically distinct double-stranded RNA (dsRNA) elements were identified in hypovirulent isolates of Sclerotinia homoeocarpa, the causal agent of dollar spot of turfgrass. The large dsRNA (L-dsRNA) was consistently present in all hypovirulent isolates, whereas the small dsRNA (S-dsRNA) was found only in some hypovirulent isolates. Virulence comparisons revealed that there was no significant difference between isolates containing one or both dsRNAs. Therefore, the L-dsRNA appears to be the genetic determinant of hypovirulence, while the S-dsRNA is not essential for hypovirulence in S. homoeocarpa. The L-dsRNA in hypovirulent isolate Sh12B of S. homoeocarpa was previously characterized as a fungal mitochondrial virus and designated Ophiostoma novo-ulmi mitovirus 3a-Sh12B (OnuMV3a-Sh12B) because it was conspecific with O. novo-ulmi mitovirus 3a-Ld from O. novo-ulmi, the causal agent of Dutch elm disease. In the present study, the nucleotide sequences of the S-dsRNAs (738 to 767 nucleotides) in hypovirulent isolates Sh12B, Sh279B, and Sh286B were determined. Nucleotide sequence analysis indicated that the S-dsRNA was not derived from the OnuMV3a dsRNA and it could not encode an RNA-dependent RNA polymerase. These results are consistent with biological data that the S-dsRNA was always associated with the L-dsRNA and was never found independently. Therefore, the S-dsRNA can be regarded as a satellite RNA of OnuMV3a in S. homoeocarpa. Northern blotting analysis indicated that nucleic acid extracts from isolate Sh12B of S. homoeocarpa contained more single (+) stranded RNA than dsRNA for this satellite RNA. The 5'- and 3'-terminal sequences of the positive strand of the S-dsRNA each could be folded into a stem-loop structure and the terminal 21 nucleotides were complementary to each other, potentially forming a panhandle structure. 相似文献
6.
ABSTRACT One hundred and thirty-two isolates of Sclerotinia homoeocarpa, the causal agent of dollar spot of turfgrass, were evaluated for virulence on swards and detached leaves of creeping bentgrass and for the presence of double-stranded RNA (dsRNA). In at least four isolates, the hypovirulent phenotype was associated with the presence of specific segments of dsRNA. In addition, these hypovirulent isolates often grew slowly on potato dextrose agar (PDA), formed thin colonies with atypical colony margins, and failed to produce typical black stroma. The hypovirulent phenotype and dsRNA were transmitted from hypovirulent isolate Sh12B to virulent isolate Sh48B, and the converted isolate was hypovirulent and contained dsRNA. The hypovirulent phenotype and dsRNA also were transmitted to at least four other isolates of the pathogen, including the fungicide-resistant, dsRNA isolate KY-7. Converted isolates of KY-7 developed the hypovirulent phenotype, grew on fungicide-amended medium, and contained dsRNA. Subcultures of hypovirulent isolate Sh12B that did not contain dsRNA were obtained through curative treatment using cycloheximide-containing medium and heat. Cured subcultures grew faster on PDA, had more typical colony morphologies, were more virulent on bentgrass leaves, and did not contain dsRNA. No cured subcultures were obtained from hypovirulent isolate Sh09B. Isolates regenerated from protoplasts of hypovirulent isolate Sh12B were not cured, remained hypovirulent, and contained dsRNA. Transmission of hypovirulence and dsRNA in S. homoeocarpa has potential as a novel approach to the management of dollar spot of turfgrass. 相似文献
7.
Two-hundred and forty-eight isolates of Rhizoctonia spp, were obtained from 13 locations in Gifu Prefecture in Japan using the plant debris particles isolation, colonization of bait tissue, and soil-clump plating methods. Of the isolates, 143 were binucleate Rhizoctonia spp., 60 were R. solani and 45 were R. zeae. Three isolates of R. solani and 54 of binucleate Rhizoctonia spp, were hypovirulent on radish, whilst all isolates of R. zeae were highly virulent, Hypovirulent strains were isolated most frequently by the plant debris particles isolation method, Hypovirulent isolates of R. solani belonged to anastomosis group 4, whilst the hypovirulent binucleate Rhizoctonia isolates belonged to AG A, AG Ba, AG G, and AG O.
Thirty-two isolates of Rhizoctotria spp, selected for hypovirulence on radish were tested on cucumber in vitro. Only five binucleate Rhizoctonia isolates and one R. solani isolate were hypovirulent on both species, and these isolates were also hypovirulent on seven other crop species. Cucumber showed wide variation in disease susceptibility to different isolates but hypovirulent isolates exhibited a consistent reaction on five different host cultivars, Pathogenicity tests using cucumber grown in soil also showed consistent reactions with isolates selected either for hypovirulence or virulence. The results support the use of cucumber in bioassays for identifying hypovirulent isolates of binucleate Rhizoctonia spp. 相似文献
Thirty-two isolates of Rhizoctotria spp, selected for hypovirulence on radish were tested on cucumber in vitro. Only five binucleate Rhizoctonia isolates and one R. solani isolate were hypovirulent on both species, and these isolates were also hypovirulent on seven other crop species. Cucumber showed wide variation in disease susceptibility to different isolates but hypovirulent isolates exhibited a consistent reaction on five different host cultivars, Pathogenicity tests using cucumber grown in soil also showed consistent reactions with isolates selected either for hypovirulence or virulence. The results support the use of cucumber in bioassays for identifying hypovirulent isolates of binucleate Rhizoctonia spp. 相似文献
8.
ABSTRACT Interspecific transmission of a hypovirulence-associated double-stranded RNA (dsRNA) and hypovirulent phenotype was attempted from hypovirulent isolate Ss275 of Sclerotinia sclerotiorum to five virulent isolates of S. minor. dsRNA and the hypovirulent phenotype were successfully transmitted to one of the five isolates, Sm10. Three putative converted isolates of Sm10 were slow growing and developed atypical colony morphologies characteristic of the hypovirulent phenotype. These isolates were assayed for virulence and produced significantly smaller lesions than isolate Sm10 on detached leaves of Romaine lettuce. One of these putative converted isolates, designated Sm10T, was tested to confirm interspecific transmission of dsRNA. In northern hybridizations, dsRNA isolated from Sm10T hybridized with a digoxigenin-labeled cDNA probe prepared from dsRNA isolated from Ss275. Random amplified polymorphic DNA analysis confirmed that isolate Sm10T was derived from Sm10 and not from Ss275 or a hybrid of the two species. The dsRNA and hypovirulent phenotype were subsequently transmitted intraspecifically from Sm10T to Sm8. To our knowledge, this is the first report of interspecific transmission of dsRNA and an associated hypovirulent phenotype between fungal plant pathogens by hyphal anastomosis. 相似文献
9.
Kanematsu S Arakawa M Oikawa Y Onoue M Osaki H Nakamura H Ikeda K Kuga-Uetake Y Nitta H Sasaki A Suzaki K Yoshida K Matsumoto N 《Phytopathology》2004,94(6):561-568
ABSTRACT White root rot, caused by Rosellinia necatrix, is a serious soilborne disease of fruit trees and other woody plants. R. necatrix isolate W370 contains 12 segments of double-stranded RNA (dsRNA) that is believed to represent a possible member of the family Reoviridae. W370 was weakly virulent and its hyphal-tip strains became dsRNA free and strongly virulent. The 12 segments of W370dsRNA were transmitted to hygromycin B-resistant strain RT37-1, derived from a dsRNA-free strain of W370 in all or none fashion through hyphal contact with W370. The W370dsRNA-transmitted strains were less virulent than their parent strain RT37-1 on apple seedlings, with mortality ranging between 0 to 16.7% in apple seedlings that were inoculated with the W370dsRNA-containing strains and 50 to 100% for seedlings inoculated with the dsRNA-free strains. Some W370dsRNA-containing strains killed greater than 16.7% of seedlings, but these were found to have lost the dsRNA in planta. These results indicate that W370dsRNA is a hypovirulence factor in R. necatrix. In addition, a strain lost one segment (S8) of W370dsRNA during subculture, and the S8-deficient mutant strain also exhibits hypovirulence in R. necatrix. 相似文献
10.
11.
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
12.
F. Deng G. J. Boland 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(2):127-137
The hypovirulence-associated mitovirus, Ophiostoma mitovirus 3a (OMV3a), has been shown to be widespread in eastern Canadian populations of Sclerotinia homoeocarpa in the form of latent infection. Latent infection by OMV3a was not associated with an apparent phenotype and did not significantly
reduce the growth and virulence of the pathogen. In the present study, we found that isolates of S. homoeocarpa latently infected by OMV3a can change to hypovirulent isolates after storage at 4 °C, and that this attenuation of virulence
was associated with increased concentration of the OMV3a virus. Recurrent observations revealed that up to 29.8% of latently
infected isolates changed to hypovirulent isolates after 21 months of storage. Transmission of OMV3a dsRNA from latently infected
isolates to virus-free isolates resulted in latent infection of the recipient isolates, indicating that latent infection by
OMV3a was not associated with genetic differences in the fungal host. The RNA genomes of the OMV3a virus in an isogenic pair
of latently infected and hypovirulent isolates were sequenced and compared. Each of the two RNAs contained an open reading
frame of 726 amino acids with conserved motifs typical of RNA-dependent RNA polymerase (RdRp). The OMV3a RNA sequences in
these two isolates share 95.1% nucleotide and 94.6% amino acid sequence identities. The development of hypovirulence from
latent infection by OMV3a virus may provide new strategies to improve the biological control efficacy of hypovirulence in
dollar spot management. 相似文献
13.
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
14.
The hyphal tip was isolated from 13 weakly or moderately virulent strains of Helicobasidium mompa to remove double-stranded (ds) RNAs and demonstrate their role as the hypovirulence factor. All of 829 hyphal tip subcultures retained dsRNAs. However, strain v670 containing two large fragments (10kb) and one small fragment (ca. 2.3kb) of dsRNA lost the largest fragment in 3 of 63 subcultures analyzed. One of the three subcultures (v670hti) was used to inoculate carrots to regain virulence compared to the parental strain v670. When isolate v670hti was paired with v670, the largest fragment was reintroduced to v670hti, and its virulence was diminished. Northern blot analysis with two probes hybridizing dsRNA fragments in most H. mompa strains revealed that the largest fragment involved in hypovirulence was different from two other fragments that are common in Japan. These results indicate that the largest dsRNA fragment in strain v670 is associated with hypovirulence in H. mompa. 相似文献
15.
Omar Darissa Günter Adam Wilhelm Sch?fer 《European journal of plant pathology / European Foundation for Plant Pathology》2012,134(1):181-189
The association of Fusarium graminearum isolate China-9 with the dsRNA mycovirus FgV-ch9 was evaluated for hypovirulence-related traits. Single conidia-originating cultures of China-9 isolate can be associated either with high, medium or low amounts of the viral dsRNAs. At high and medium dsRNA levels, China-9 isolates exhibit reduced mycelia growth rate and conidiation capacity, abnormal colony morphology, disorganized cytoplasm, as well as reduced virulence for wheat and maize plants. At low dsRNA levels the fungus shows no symptoms, however, the RNA segments can be detected by RT-PCR. Transfection of the virulent F. graminearum PH-1 isolate with purified Virus-like Particles (VLPs) of FgV-ch9 reduced its conidiation capacity, perithecia formation, and pathogenicity for wheat and maize several folds. These results further demonstrate that FgV-ch9 is associated with hypovirulence of F. graminearum. 相似文献
16.
Twenty-eight isolates of Fusarium moniliforme were established from bakanae-infected rice plants of a range of cultivars collected from various localities in Haryana, India. They were characterized by vegetative compatibility, virulence pattern on five paddy cultivars, and biosynthesis of gibberellins and were assigned to 10 vegetative compatibility groups (VCGs). Isolates from different VCGs and also within the same VCG varied considerably in virulence and GA3 production. The 28 isolates were categorized into five gibberellic acid production groups (GPG-I–GPG-V) and five virulence groups (VG-I–VG-V). Vegetative compatibility was independent of pathogenicity and of ability to produce GA3 . However, GA3 production was positively correlated ( r = 0.731) with pathogenic behaviour. 相似文献
17.
Nadia Korolev Encarnación Pérez-Artés José Bejarano-Alcázar Dolores Rodríguez-Jurado Jaacov Katan Talma Katan Rafael M. Jiménez-Díaz 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(4):443-456
Genetic diversity and phenotypic diversity in Verticillium dahliae populations on cotton were studied among 62 isolates from Spain and 49 isolates from Israel, using vegetative compatibility grouping (VCG), virulence and molecular assays. In Spain, defoliating V. dahliae isolates (D pathotype) belong to VCG1, and non-defoliating isolates (ND) belong to VCG2A (often associated with tomato) and VCG4B (often associated with potato). The D pathotype was not identified in Israel. The ND pathotype in Israel is comprised of VCG2B and VCG4B. Isolates in VCG2B and VCG4B ranged in virulence from weakly virulent to highly virulent. The highly virulent isolates induced either partial defoliation or no defoliation. Virulence characteristics varied with inoculation method and cotton cultivar. Highly virulent isolates from Israel were as virulent as D isolates from Spain under conditions conducive to severe disease. The D pathotype is pathologically and genetically homogeneous, whereas the ND pathotype is heterogeneous with respect to virulence, VCG, and molecular markers based on single-primer RAPD and on PCR primer pairs. 相似文献
18.
N. Bharathan † H. Saso L. Gudipati S. Bharathan K. Whited K. Anthony 《Plant pathology》2005,54(2):196-203
The occurrence, distribution, and genetic relatedness of double-stranded RNA (dsRNA) components from 36 isolates of Rhizoctonia solani belonging to nine anastomosis groups (AGs) were studied using electrophoretic analysis and RNA–RNA blot hybridization. DsRNA was consistently detected in all 36 isolates. The size of the dsRNA components varied considerably, ranging from 0·74 to 23 kb. Two thirds of isolates possessed different size dsRNA components. Only two of the isolates had small size dsRNA between 0·5 and 1·0 kb. The biotin-labelled dsRNA probes provided the sensitivity and specificity required to study genetic relationships of dsRNA. As little as 10 pg of 'hybridizing' dsRNA could be detected using biotin-labelled total dsRNA with no detectable nonspecific-hybridization. Results from several dot-spot as well as RNA–RNA gel hybridization experiments revealed considerable sequence heterogeneity among dsRNA components within each isolate or isolates from the same AG. 相似文献
19.
Forty-three isolates ofVerticillium lecanii from insects, phytopathogenic fungi and other substrates were tested for vegetative compatibility by observing heterokaryon
formation among complementary nitrate-nonutilizing (nit) mutants.nit mutants were isolated from 42/43 strains examined. Twenty-one isolates were self-incompatible, and the remaining 21 isolates
were divided into 14 vegetative compatibility groups (VCGs): ten containing only a single strain each, and the remaining four
containing two to four isolates each. Members of isolates in each of these VCGs all shared the same IGS haplotype. Further,
the isolates within a VCG were correlated with one another in part by fragment patterns of mt-LrDNA, -SrDNA, Bt-2 and H4 region,
by PCR-RFLP and -SSCP, but not by dsRNA. Two isolates belonging to VL-J2 have high virulence to aphids, whereas strains from
VL-J1 lack this character. These findings indicate that two VCGs (VL-J1 and -J2) may originate from two distinct clonal lineages.
Alternatively, high VCG diversity and HSI frequency ofV. lecanii might be associated with an array of distinct lineages. These data not only suggest relationships among DNA polymorphisms,
virulence, and VCG, but also demonstrate genetic heterogeneity ofV. lecanii.
http://www.phytoparasitica.org posting Sept. 30, 2003. 相似文献
20.
A diseased isolate of Ophiostoma ulmi was found to contain 10 segments of double-stranded RNA (dsRNA) with molecular weights ranging from 2.40 x 106 to 0.23 x 106 . In contrast seven other healthy isolates in the same vegetative compatibility group contained either no dsRNA or up to four dsRNA segments. Transmission of the disease to healthy isolates by hyphal anastomosis was accompanied by-transmission of the 10 dsRNA segments. In a genetic cross in which the diseased isolate acted as the female parent single-ascospore progeny were healthy and either contained no dsRNA or only one segment of dsRNA. When elm trees were inoculated with diseased isolates, subsequent reisolations were healthy and retained only two to seven of the dsRNA segments or were diseased and retained all 10 dsRNA segments. Following conidiogenesis a diseased isolate gave rise to single-conidial progeny which were either slow growing and diseased, like their parent, with all 10 dsRNA segments, or faster growing like healthy isolates. Some of the faster growing conidial isolates retained only two to seven of the dsRNA segments and were disease-free. However a majority of the faster growing conidial isolates retained all 10 dsRN A segments and were shown to carry the disease in a latent form. The possibility that the disease of O. ulmi is conferred by specific segments of dsRNA and the potential of d-factors for the control of Dutch elm disease are discussed. 相似文献