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1.
This study investigated the prevalence and identity of botryosphaeriaceous dieback pathogens in necrotic grapevines tissues in New Zealand vineyards, and other woody hosts growing nearby. The presumptive identities of the isolates by conidial and cultural morphology were confirmed with ITS sequence data as Neofusicoccum australe, N. luteum, N. parvum and Diplodia seriata. They were isolated predominantly from necrotic stems of grapevine and other hosts, but also from leaves, flowers and wood debris of grapevines. Inoculation with conidia and mycelium of multiple isolates of each species onto excised and attached green shoots and trunks of five grapevine varieties, Cabernet sauvignon, Chardonnay, Pinot noir, Riesling, and Sauvignon blanc, showed that all varieties became infected to a similar extent. All species except D. seriata were pathogenic, irrespective of the host source, with N. luteum being the most and D. mutila the least pathogenic (P < 0.05). On trunks, N. parvum caused cankers and the other pathogenic species caused die-back when the inoculated vines became winter-dormant. Conidia were produced from green shoot lesions and die-back wood, which indicates potential inoculum sources for vineyard infection.  相似文献   

2.

The family Botryosphaeriaceae is one of the most widespread and cosmopolitan endophytic group of fungi. Every year, species of this family cause severe damages on table and wine grape production, worldwide. However, this threat is still poorly known in Algeria. In this study, a large number of Botryosphaeriaceae-like isolates were obtained from symptomatic grapevines collected from eight regions with different ecological conditions, namely: Boumerdès, Médéa, Algiers, Tipaza, El Taref, Sidi Bel Abbes, Biskra and Adrar. The isolates were identified using DNA sequences of the translation elongation factor (tef1-α) and internal transcribed spacer (ITS) regions. Eleven species belonging to six genera, including Neofusicoccum parvum, N. algeriense, N. vitifusiforme, N. stellenboschiana, N. luteum, Diplodia seriata, D. olivarum, Lasiodiplodia theobromae, Dothiorella sarmentorum, Botryosphaeria dothidea and Neoscytalidium dimidiatum were identified. The spatial distribution of the Botryosphaeriaceae showed that D. seriata and N. stellenboschiana were the most widespread in the Algerian vineyards, while L. theobromae was recorded in the desert region of Biskra. Pathogenicity trials showed that all species were pathogenic on detached green shoots of grapevine, with N. parvum and L. theobromae being the most aggressive.

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3.
Stemphylium botryosum pathogenic on alfalfa (Medicago sativa) produced a phytotoxin in a defined liquid medium which caused symptoms similar in sequence and appearance to stemphylium leafspot lesion development on attached alfalfa leaflets. The molecular weight of the phytotoxin was estimated to be 19500 by gel filtration chromatography. Treatment of partially purified phytotoxin with proteinase K or subtilisin resulted in loss of phytotoxic activity. Action of the proteases in inducing loss of phytotoxicity was inhibited by phenylmethylsulphonyl fluoride. Concentrated culture filtrates were fractionated by chromatofocusing, HPLC ion-exchange and gel filtration. Gel filtration also was followed by non-denaturing electrophoresis or isoelectric focusing (IEF). Analysis of sequential fractions from each procedure by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated that phytotoxic activity was consistently coincident with the presence of two major polypeptides (Mr = 26900 ± 2%; 19500 ± 4%) and a triplet of polypeptides (Mr = 15500). The constant association between the three polypeptides suggested an intermolecular interaction during fractionation. The phytotoxic activity eluted from the chromatofocusing column between pH 5·79 and 5·43 whereas IEF estimated the isoelectric point to be between 5·40 and 5·02.Immobilized concanavalin A and wheat germ lectin failed to bind phytotoxicity. Proteolytic activity in some phytotoxic gel filtration fractions was reduced by addition of phenyl-methylsulphonyl fluoride and separated from phytotoxicity by non-denaturing electrophoresis, indicating that phytotoxicity was not due to serine protease activity.Pathogenicity tests of the cool-temperature biotype on 20 plant species representing eight plant families resulted in a compatible interaction only on M. sativa and M. polymorpha. In contrast, sensitivity to the phytotoxin was observed on both pathogen-resistant and susceptible alfalfa clones along with all other plants tested with the exception of Triticum aestivum, Zea mays, Apium graveolens and Melilotus officinalis, indicating non-host-specificity of the phytotoxic polypeptides produced by the cool-temperature biotype.  相似文献   

4.
Phaeomoniella chlamydospora (Pch) and Togninia minima (Tmi) produced scytalone, isosclerone and pullulans in liquid cultures, as well as in calli. Secondary metabolites and host defense compounds were shown to occur in calli of Vitis vinifera cv. Italia and cv. Matilde infected by the esca-associated fungi Pch, Tmi and Fomitiporia mediterranea (Fme). Calli of both cvs. were grown as dual cultures with Pch, Tmi and Fme. The fungi grew well in the presence of calli of both cvs., but callus growth was reduced. Accumulation and changes of total phenolics and recurring phenolics, and of two phytotoxic pentaketides and pullulans were analyzed by HPLC. On comparing results for cv. Italia and cv. Matilde, it can be seen that concentrations of phenolics are strongly related to the cv. The paper discusses the possible relationship between melanin biosynthesis in Pch and Tmi, which utilize pentaketide metabolites as intermediates and their pathogenicity related to phytotoxity of scytalone and isosclerone.  相似文献   

5.
The yellow leaf curl disease of tomato is caused by a complex of virus species, two of which, tomato yellow leaf curl virus (TYLCV)-Sar and TYLCV-Is, are involved in epidemics of southern Spain. Plants of Mercurialis ambigua and Solanum luteum showing abnormal upward leaf curling and leaf distortion collected in the vicinity of tomato crops were found to be naturally infected with TYLCV-Is and TYLCV-Sar, respectively. These weed species, as well as Datura stramonium and S. nigrum, which had also been found to be naturally infected by TYLCVs in the same region in previous studies, were tested for susceptibility to TYLCV-Sar or TYLCV-Is by Agrobacterium tumefaciens-mediated and by Bemisia tabaci inoculation. Results indicated that both TYLCV-Sar and TYLCV-Is were able to infect D. stramonium and M. ambigua, whereas only TYLCV-Sar infected S. nigrum and S. luteum. Implications for the epidemiology of TYLCV are discussed. This is the first report of M.ambigua and S. luteum as hosts of TYLCV.  相似文献   

6.
Sphaeropsis sapinea was repeatedly isolated in Sardinia from symptomatic samples of the upper part of declining pine (Pinus radiata) plants. Observed symptoms mainly consisted of foliage chlorosis, drying of needles and cankers on branches. The S. sapinea strains were shown to produce phytotoxic metabolites in culture filtrates. Three metabolites were isolated for the first time from this fungus and identified by their spectroscopic and optical properties as R-(−)-mellein, (3R,4R)-4-hydroxymellein and (3R,4S)-4-hydroxymellein. When assayed for phytotoxic and antifungal activities on host and non-host plants and on some phytopathogenic fungi, the R-(−)-mellein showed significant activity, while the other two 3,4-dihydroisocoumarins showed only a synergic activity in both tests.  相似文献   

7.
To determine presence of infection by botryosphaeriaceous fungi in plant materials from different grapevine nurseries, different types of grafted plants and cuttings were requested from nine grapevine nurseries around New Zealand. Of the 311 propagation materials and plants collected, 23?% were infected by botryosphaeriaceous fungi. The highest incidence was in failed grafted plants (33?%), followed by Grade 1 plants (28?%), rootstock cuttings (19?%), scion cuttings (17?%) and Grade 2 plants (7?%). For grafted plants, most isolates (80?%) were from near the graft unions while infections on rootstocks and scion cuttings were mostly from the middle (39?%) and basal parts (46?%). Identification of isolates by morphological and molecular methods showed that seven species were present in nurseries, being Neofusicoccum luteum (57?%), N. parvum (18?%), N. australe (8?%), Diplodia mutila (8?%), Botryosphaeria dothidea (5?%) and D. seriata (3?%), with one novel isolate of N. macroclavatum. These results show that Botryosphaeriaceae species were present in propagation materials and in the grafted plants supplied by nurseries, indicating that some of the current vineyard infections may have originated in the propagation nurseries.  相似文献   

8.
Botryosphaeriaceous species are significant grapevine trunk pathogens worldwide, which can be difficult to identify to species level using conventional morphological methods. This study developed and optimized a quick, reliable molecular identification method that could facilitate investigations into the epidemiology of these diseases in vineyards. The multi‐species primers, BOT100F and BOT472R, amplified a 371–372 bp portion of the rRNA gene region from the six botryosphaeriaceous species commonly found in New Zealand vineyards. In silico analysis indicated that they would amplify DNA from six of the 12 lineages of the Botryosphaeriaceae, including all of the main species pathogenic to grapevines. A detection sensitivity of 1 and 0·1 pg DNA in standard and nested PCR, respectively, was achieved and this was calculated as equivalent to 2·5 conidia. Validation of the primers for environmental samples showed that their specificity was not compromized by the presence of competing DNA templates extracted from wood and soil. Single stranded conformational polymorphism (SSCP) analysis of the amplicons could resolve Neofusicoccum australe, N. luteum, Diplodia mutila and D. seriata, but did not differentiate between N. parvum and N. ribis. The optimized PCR‐SSCP was used to identify botryosphaeriaceous species present in rainwater traps collected over 1 year in a vineyard known to contain infected vines. It could detect multiple species in individual samples and demonstrated differences in the dispersal patterns of conidia from different species. Given the specificity and sensitivity of this method it could prove useful in epidemiology studies involving the numerous botryosphaeriaceous species that infect a wide range of host species.  相似文献   

9.
Culture filtrates of 17 different fungal species thriving upon other fungi were tested for their ability to reduce sporulation of cucumber powdery mildew,Sphaerotheca fuliginea.All culture filtrates reduced the number of healthy conidiophores. However, the differences in activity between the various treatments were not as conspicuous as after application of spore suspensions. The best results were obtained with culture filtrates ofCalcarisporium arbuscula. These reduced the number of healthy conidiophores to ca. 2% of the unsprayed control plants.  相似文献   

10.
When the esca-associated fungi Phaeomoniella chlamydospora (Pch), Togninia minima (Tmi) and Fomitiporia mediterranea (Fme) were grown in liquid stationary cultures, it was seen that they were able to live in media containing resveratrol (RES) or tannic acid (TA) as the sole carbon source and that the fungi were able to convert both compounds. Particular attention is paid here to detecting RES and TA conversion. Pch, Tmi and Fme were partially inhibited by RES or TA. Pch, Tmi and Fme produced extracellular tannase, laccase and peroxidase enzymes in liquid or agarized cultures, whether glucose was present or not. When colonies of Pch, Tmi and Fme were confronted, they showed spatially and temporally heterogeneous patterns of laccase and peroxidase activity. The results indicate the non-synergistic, competitive association of Pch and Tmi and the inhibition of Fme growth. Muconic acid, a well-known intermediate in a large number of lignin and phenol oxidative processes, can partly or completely inhibit the lignolytic agent Fme, but is tolerated by Pch and Tmi. An explanation for wood pigmentation patterns by Pch, Tmi and Fme is given.  相似文献   

11.
Sampling at blueberry farms found Botryosphaeriaceae fungi in five of seven farms sampled; overall incidence was 41.4%, with Neofusicoccum australe (79.0%), N. luteum (8.0%), N. ribis (8.0%) and N. parvum (5.0%). Sampling of nursery plants found infections in all four nurseries with 45% incidence in mainly asymptomatic plants, which were infected with N. australe (66.0%), N. parvum (31.5%) and N. ribis (2.5%). Asymptomatic propagation cuttings from one nursery were found to have external contamination of Botryosphaeriaceae DNA (90.0%) and internal infection (65.0%) by the four main species found in the blueberry farms and nurseries. For propagation media nested PCR showed that out of the 98 samples received, 43 samples were positive for the presence of Botryosphaeriaceae DNA (44.0%). Results from the SSCP indicated that N. australe, N. luteum, N. parvum/ N. ribis and Diplodia mutila were present in the propagation media received. Isolates of the four main species recovered from farms and nurseries were pathogenic on blueberry stems but pathogenicity differed significantly between species and isolates within a species, with N. ribis being the most pathogenic, then N. parvum, N. luteum and N. australe. Overall, the high rate of infection in nursery plants indicated that nurseries can be a major source of infection for blueberry farms. Since propagating cuttings are the likely sources of infection for nurseries, these should be targeted in the control strategies.  相似文献   

12.
Antibiosis has been shown to be an important mode of action by Trichoderma species used in the protection of grapevine pruning wounds from infection by trunk pathogens. The major active compound from Trichoderma isolates known to protect grapevine pruning wounds from trunk pathogen infection was isolated and identified. The compound, a 6‐pentyl‐α‐pyrone (6PP), was found to be the major secondary metabolite, by quantity, which accumulated in the culture filtrate of Tharzianum isolate T77 and the two Tatroviride isolates UST1 and UST2. Benzimidazole resistant mutants generated from these isolates also produced 6PP as their main secondary metabolite, except for a mutant of T77 that had lost its ability to produce 6PP. The isolates UST1 and UST2 were co‐cultured with the grapevine trunk pathogens Eutypa lata and Neofusicoccum parvum in a minimal defined medium and a grapevine cane‐based medium (GCBM). Co‐culturing UST1 with Nparvum induced 6PP production in the minimal defined medium and the GCBM. The production of 6PP by UST2 was induced in the GCBM, while co‐culturing with the two trunk pathogens either reduced or had no effect on 6PP production. Mycelial growth and ascospore/conidia germination of Elata, Naustrale, Nparvum and Phaeomoniella chlamydospora were inhibited by 6PP in a concentration‐dependent manner. The results show that the presence of Nparvum and grapevine wood elicits the production of 6PP, suggesting that this metabolite is involved in Trichoderma–pathogen interactions on grapevine pruning wounds.  相似文献   

13.
14.
Unique bands were identified in single isolates of Neofusicoccum parvum and Neofusicoccum luteum using universally primed polymerase chain reaction (UP‐PCR) analysis of isolates obtained from grapevines and non‐grapevine hosts in New Zealand, Australia, South Africa and the USA. Primers were designed to amplify a 1550 bp portion of the 1573 bp marker band from N. parvum isolate B2141 and a 510 bp portion of the 524 bp marker band from N. luteum isolate G51a2. A PCR‐RFLP assay was developed to distinguish the N. parvum isolate B2141 from other N. parvum isolates, based on a polymorphism found in the marker band using the TaqI restriction endonuclease. For N. luteum isolate G51a2, the designed primers were specific at an annealing temperature of 63°C in the PCR. The sensitivity threshold of the N. parvum and N. luteum isolate‐specific markers was 50 pg and 5 pg, respectively, when used in standard PCR with purified genomic DNA. The sensitivity of the N. parvum isolate‐specific marker was increased to 0·5 pg by nested PCR. The specificity test of both isolate‐specific markers with six other Botryosphaeriaceae spp. showed that they were specific to their respective species and isolates. Both markers were able to detect the conidia of N. parvum and N. luteum marker isolates in rainwater samples collected at different distances from an inoculation point in the vineyard. The results showed that rain splash could disperse the conidia of both of these species up to 2 m from the inoculum point in a single rainfall event.  相似文献   

15.
Several species of Botryosphaeriaceae and Phaeomoniella chlamydospora are common agents of grapevine decline worldwide. Currently, the use of culture independent PCR based techniques for detection of Botryosphaeriaceae within grapevine tissues has been limited to Botryosphaeria dothidea. In the present study, two Botryosphaeriaceae specific nested PCR assays were developed. One with a narrow target range, to detect Neofusicoccum parvum and the closely related species complex (Neofusicoccum parvum/N. ribis sensu Pavlic et al. Molecular Phylogenetics and Evolution 51:259–268, 2009) and another, with a wider range, to detect all 17 species of Botryosphaeriaceae which have been reported as potential wood pathogens of grapevine. The effectiveness of these assays was validated in vivo on naturally infected wood samples collected from standing vines and dormant grafted rooted cuttings commercialized in Italy by different nurseries in different years. All samples were also screened by means of a previously published nested PCR assay specific for Phaeomoniella chlamydospora. It was found that: 1) propagation material may play an important role as source of primary inoculum, not only of Phaeomoniella chlamydospora, as previously reported, but also for members of the Botryosphaeriaceae, among which Neofusicoccum parvum, Botryosphaeria dothidea and Diplodia seriata are the most common, and 2) multiple infections by different species belonging to Botryosphaeriaceae and/or Phaeomoniella chlamydospora occur frequently both in standing vines and propagation material. This last finding supports the hypothesis that at least some of the non-specific symptoms of grapevine decline may be due to the presence of different pathogens within host tissues.  相似文献   

16.
Loquat (Eriobotrya japonica) is an important subtropical fruit crop in Spain and other Mediterranean countries. In recent years, characteristic symptoms of branch canker and dieback have been observed in the main cultivated areas of loquat in Spain. The goal of this study was to identify and characterize the species of Botryosphaeriaceae associated with these symptoms. For this, 36 affected orchards were surveyed between 2010 and 2011 in six provinces of southeastern Spain. Eighty‐four isolates belonging to the family Botryosphaeriaceae were recovered from samples with symptoms. These isolates were characterized by means of phenotypical studies, DNA sequence analyses of the internal transcribed spacer (ITS) and part of the translation elongation factor 1‐α regions, and pathogenicity tests. Ten fungal species were identified: Diplodia malorum, Diplodia olivarum, Diplodia seriata, Diplodia pseudoseriata/Diplodia alatafructa, Diplodia sp., Dothiorella sarmentorum, Neofusicoccum mediterraneum, N. parvum, Spencermartinsia plurivora and S. viticola. In addition, Diplodia eriobotryicola and Dothiorella eriobotryae are newly described. The most frequent species isolated from cankers was D. seriata and, as far as is known, this is the first report of D. malorum, and species belonging to the complex D. pseudoseriata/D. alatafructa, in Spain. All species were pathogenic to 1‐year‐old loquat plants cv. Algerie, with Diplodia sp. and S. viticola as the most virulent.  相似文献   

17.
This study investigated the sources of inoculum of Botyosphaeriaceae species in three commercial grapevine nurseries in New Zealand. Botryosphaeriaceae propagules were detected on the surfaces of 33 to 100?% of canes and 33?% of dead grapevine materials using microscopy, plating assays and PCR with Botryosphaeriaceae multi-species primers (Bot100F/Bot472R). Isolations also showed that 15 to 68?% of the canes were internally infected by Botryosphaeriaceae species, with Neofusicoccum luteum and N. parvum being the most predominant species. Incidence varied between nurseries, with Nursery 5 having highest N. luteum incidence (53?%) and Nursery 3 having highest N. parvum incidence (88?%). Botryosphaeriaceae DNA was detected in rain-water run-off from the mother-vine canopy, but not in soil samples collected around infected mother-vines. However, samples from the nursery propagation stages had no visible or viable Botryosphaeriaceae propagules although PCR using multi-species primers detected Botryosphaeriaceae DNA from wash and hydration tanks, on grafting tools and in callusing media from the different nurseries. The single-stranded conformational polymorphism (SSCP) was able to identify N. parvum, N. luteum and Diplodia mutila as the most common species present in the nursery system. Overall results indicated that the canes grown in mother-vine blocks were the most likely source of inoculum for infection of young grafted plants by Botryosphaeriaceae species.  相似文献   

18.
19.
Four species so far classified in Pseudocercosporella or Ramulispora (hyphomycetes) are associated with eyespot disease symptoms of cereals. Two of these have been linked to teleomorphs that were described in Tapesia. Sequence data derived from the Internal Transcribed Spacer region (ITS1, 5.8S and ITS2) of the rDNA operon showed, however, that the eyespot fungi associated with Tapesia are not congeneric with Ramulispora sorghi, the type of Ramulispora. The genus name Tapesia is now rejected in favour of the conserved name Mollisia, which appears to comprise heterogeneous fungi. Tapesia yallundae is not closely related to the type of Mollisia, M. cinerea, but clusters separately, being more closely allied to species with Cadophora anamorphs. A new holomorph genus, Oculimacula, is therefore proposed for teleomorphs of the eyespot fungi, while the anamorphs are accommodated in Helgardia gen. nov.  相似文献   

20.
Sudden death syndrome (SDS) of soybean is a fungal disease caused by at least four distinct Fusarium species: F. tucumaniae, F. virguliforme, F. brasiliense, and F. crassistipitatum. All four species are present in Argentina. These fungi are soilborne pathogens that only colonize roots and cause root necrosis. However, damage also reaches the aboveground part of the plant, and foliar chlorosis and necrosis, followed by premature defoliation, can be observed. Although the pathogenicity and phytotoxicity of F. virguliforme has been well characterized, knowledge regarding disease development by other fungal species is scarce. In this study, two plant species, soybean (Glycine max) and Arabidopsis thaliana, and isolates from two fungal species, F. tucumaniae and F. crassistipitatum, were used to comparatively analyse the fungal pathogenicity and the phytotoxicity of volatile organic compounds (VOCs) and cell-free culture filtrates. Fungal inoculation had a significant effect on plant growth, regardless of the plant species. In addition, infected soybean plants showed disease incidence and foliar and root symptoms. Inhibition of A. thaliana growth was not due to VOCs emitted by fungi. Instead, both pathogens were shown to produce toxins that caused typical SDS foliar symptoms in soybean and root length reduction in A. thaliana. As far as we know, this is the first report that demonstrates that F. tucumaniae and F. crassistipitatum affect A. thaliana growth and emit VOCs, and that F. crassistipitatum produces toxins.  相似文献   

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