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1.
Five commercial nurseries were sampled in 2007 to evaluate the grapevine nursery propagation process as a source of Petri disease pathogens (Phaeoacremonium spp. and Phaeomoniella chlamydospora). Samples were taken at four stages of the propagation process: pre-grafting hydration tanks, scissors used for cutting buds, grafting machines and peat used to promote root development. All samples were analysed using two different techniques: nested PCR using specific primers for Phaeoacremonium spp. (Pm1/Pm2) and Pa. chlamydospora (Pch1/Pch2); and fungal isolation by culturing on semi-selective medium. Either Phaeoacremonium spp. or Pa. chlamydospora were detected at any of these stages, and more importantly they were viable since they were detected by isolating on culturing medium. Additionally, the importance of grapevine rootstock mother fields as sources of inoculum in the nurseries was studied. Fourteen grapevine rootstock mother fields were surveyed in 2006 and 2007 for the occurrence of fungal trunk pathogens. A total of 16.4% and 30% of the plants sampled in 2006 and 2007, respectively were infected. Petri disease pathogens (Pa. chlamydospora, Phaeoacremonium aleophilum, Pm. parasiticum) and several Botryosphaeriaceae species (Neofusicoccum parvum, Botryosphaeria dothidea, Lasiodiplodia theobromae, N. australe, N. mediterraneum and N. vitifusiforme) and Phomopsis viticola were isolated. This is the first time N. mediterraneum has been isolated from grapevines and the first report of N. australe, N. mediterraneum and N. vitifusiforme in Spain. This work shows that grapevine rootstock mother plants and the propagation process of grapevine plants should be considered as important sources of inoculum for fungal trunk pathogens, and especially of Petri disease pathogens.  相似文献   

2.
Wound protection during all stages of grapevine propagation is of utmost importance to prevent infection of propagation material by decline and dieback pathogens. In semi-commercial nursery trials, grapevine rootstock and scion cuttings were soaked in water (control), chemical or biological sanitation products prior to cold storage, prior to grafting (machine- or hand-grafting) and prior to planting in field nurseries. Natural infection levels in basal ends and graft unions of uprooted nursery grapevines were evaluated 8 months after planting. Total pathogen incidences in the water-treated control plants ranged from 30% in basal ends to 13.5% in graft unions. Phaeomoniella chlamydospora was the most commonly isolated pathogen, followed by Phaeoacremonium, Cylindrocarpon + Campylocarpon, Botryosphaeria and Phomopsis spp. Machine-grafted unions generally had lower pathogen incidences compared with hand-grafted graft unions. In general, repeated soak-treatments of propagation material in the tested products resulted in reduced pathogen incidences in nursery grapevines. However, products containing T. harzianum (Trichoflow-T), hydrogen peroxide (Bio-sterilizer) and 8-hydroxyquinoline sulphate (Chinosol) gave inconsistent results, whereas Bronocide (a blend of halogenated alcohols and water) proved to be a good sterilising agent, but reduced certifiable plant yield significantly. Benomyl (at 100 g/100 l), Sporekill (a patented didecyldimethylammonium chloride formulation at 150 ml/100 l) and captan (at 1000 ml/100 l) were consistently the best treatments as growth parameters were not negatively influenced and pathogen incidences in basal ends and graft unions of uprooted plants were reduced.  相似文献   

3.
Trunk disease pathogens of grapevines, viz. Phaeomoniella chlamydospora, Eutypa lata and several species in Botryosphaeriaceae, Phaeoacremonium and Phomopsis are known to infect fresh pruning wounds by means of air-borne inoculum released after rainfall or prolonged periods of high relative humidity. Recent surveys have demonstrated that most or all of these pathogens are present in climatically diverse grape growing regions of South Africa. However, the factors controlling spore dispersal of these pathogens in vineyards were largely unknown. To address this question, spore trapping was done in a Chenin Blanc vineyard in the Stellenbosch area, South Africa, for 14 weeks during the grapevine pruning period from June to mid-September of 2004 and 2005. Hourly recordings of weather data were done by a weather station in the row adjacent to the spore trap. Spores of E. lata and Phomopsis and species in Botryosphaeriaceae were trapped throughout the trapping periods of 2004 and 2005, with higher levels of trapped spores recorded in 2005. The spores of all three pathogens were trapped during or after periods of rainfall and/or high relative humidity. In neither of the 2 years were spores of Pa. chlamydospora or Phaeoacremonium spp. trapped. Results indicated that spore event incidence, as well as the amount of spores released during a spore event of above-mentioned pathogens, were governed by rainfall, relative humidity, temperature and wind speed prior to and during the spore events.  相似文献   

4.
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   

5.
During a 6-year study, grapevine propagation materials and young grapevines were analysed to evaluate the presence of internal wood discolouration and the occurrence of fungal species involved in Petri disease. The intensity of wood discolouration increased with the ageing of the plants. The maximum incidence of dark streaks was observed in the rootstock while necrosis originating from buds or nodes were notably present in the trunk and cordon of older vines. In contrast, the highest levels of brown-red halo symptoms, defined as discoloured areas around the pith, were recorded in the early growth stages. Phaeoacremonium spp. and Phaeomoniella chlamydospora were usually isolated from the rooted-grafts and the 3-year old plants, respectively. The number of infected grapevines increased with age. Most of the P. chlamydospora strains were isolated from dark streaks or dots, while Phaeoacremonium spp. were detected in brown-red halo symptoms and other symptomatic or asymptomatic wood. The greatest incidence of the two fungal taxa was recorded in the lower parts of the grapevine, including the roots and rootstock.  相似文献   

6.
Esca is one of the most important grapevine trunk diseases, and it can induce severe decline. In the past, the disease occurred mostly on mature vines, but today it is also present in young vineyards. The aim of this study was to investigate the incidence of esca in young (< 7 years old) and mature (> 11 years old) vineyards on cvs Montepulciano, Sangiovese, Verdicchio and Passerina located in the main viticultural areas of the Marche Region, central-eastern Italy. The average incidence of diseased plants was higher in mature (32.6%) than young (5.2%) vineyards, and Verdicchio and Passerina appeared to be the most sensitive among the cultivars considered, followed by Sangiovese and Montepulciano. The analysis of the spatial spread of esca carried out in two mature vineyards on cv. Verdicchio and a young vineyard on cv. Sangiovese showed a fluctuation in the numbers of infected plants over the three years of observation. The fungi associated with symptomatic plants were detected by classical and molecular tools. Isolation on agar media yielded colonies of Phaeomoniella chlamydospora (Pch), Botryosphaeria spp. (Bot), Fomitiporia mediterranea (Fomed) and, sporadically, Phaeoacremonium aleophilum (Pal). In samples from young plants, Bot and Pch were recurrent, while Pch and Fomed were found in mature vines and old rootstocks. Molecular detection with specific primer pairs for Pch, Pal, Fomed, and B. dothidea confirmed the data obtained using classical tools, and in some cases it was more sensitive. This study thus provides a further contribution to the association between causal agents and esca symptoms, and it confirms the importance of molecular tools for a sensitive detection of associated pathogens, which can also be present in propagative materials.  相似文献   

7.
Esca and Petri disease, caused by Phaeoa-cremonium, and other grapevine decline diseases, such as eutypa dieback, are responsible for serious economic losses to the wine industry worldwide. In the present work, 175 isolates of Phaeoacremonium spp. were collected (mostly in the region of Castilla y León, Spain) from vines either asymptomatic or symptomatic for grapevine decline diseases. The sequences of DNA fragments of 30 isolates were analysed. Amplicons of ITS, and partial gene of the β-tubulin, actin, calmodulin and translation elongation factor 1-α [EF1-α], were obtained by PCR. This is the first time that any exon of the EF1-α gene or exons 6–7 of the β-tubulin gene of seven Phaeoacremonium spp. have been amplified. Amplicons of the calmodulin and EF1-α exons were the most informative in terms of species differentiation: only 52.6 % and 56.6 % similarity across six and seven species was respectively seen. Phylogenetic analysis of combined DNA sequences revealed five Phaeoacremonium species isolated from the sampled plants; P. aleophilum was the most common. Four other species were found, however only one isolate each. P. mortoniae and P. iranianum are here reported for the first time on grapevines in the region of Castilla y León and the neighbouring region of La Rioja respectively. In total, 29 nucleotide differences among the studied gene fragments were seen across 23 isolates of P. aleophilum. Network analysis showed these Spanish P. aleophilum isolates to fall into two main groups of genotypes. P. aleophilum genotypes belonging to group 1 were mostly isolated from young grapevines affected by Petri disease but genotypes included in group 2 were isolated from adult plants showing esca or eutypa dieback symptoms.  相似文献   

8.
Phaeoacremonium aleophilum is a fungal pathogen implicated in esca, a devastating disease affecting grapevines around the world. We have previously reported that the fungus secreted in its culture medium a variety of polypeptides, which allowed us to develop a serological method of detection. In this method, rabbit antibodies raised against the polypeptide fraction recognized secreted fungal proteins with high sensitivity (commonly 1 ng). These antibodies were specific since they cross-reacted with polypeptides secreted by various strains of Pm. aleophilum, but not with the proteins secreted by many other fungal pathogens implicated in other grapevine infections. Importantly, as shown by ELISA tests and immunolocalization, they did not cross-react with the secreted polypeptides of Eutypa lata (agent of Eutypa dieback), Neofusicoccum parvum (found in Black Dead Arm), and Phaeomoniella chlamydospora (also found in the fungal complex inducing esca). This serological approach permitted the development of a reliable dot-blot method to detect the presence in woody members of Pm. aleophilum in selectively infected trunk and canes. This method of diagnosis is rapid, easy to perform and non destructive for grapevines. Advantages and drawbacks of the method are discussed.  相似文献   

9.
Secondary metabolites and host defense compounds were shown to occur in xylem sap, and leaves of Vitis vinifera cv. Italia and cv. Matilde naturally infected by the esca-associated fungi Phaeomoniella chlamydospora (Pch), Togninia minima (Tmi) and Fomitiporia mediterranea (Fme). Samples of xylem sap and leaves were collected from healthy vines and from vines showing severe symptoms of brown wood-streaking caused by Pch and Tmi, or from vines with symptoms of both brown wood-streaking and white rot caused by Fme. Xylem sap collection was carried out during the early spring of 2003 and 2004, corresponding to the phenological phases: (A) cotton bud; (B) green tip; (C) leaves out; (D) stretched out leaves; and (E) visible clusters. In the present work we have studied the accumulation of biomolecules (pentaketides and α-glucans), host defense compounds (benzaldehydes, benzoic acid and cinnamic acid derivatives, flavonols, flavanols, flavan-3-ol derivatives and stilbenes) at different stages of grapevine development. Accumulation and changes in total phenolics and recurring phenolics, and of three phytotoxic secondary metabolites (scytalone, isosclerone and pullulan) were analyzed by HPLC. On comparing results for cv. Italia and cv. Matilde, it can be seen that phenolic concentrations are strongly related to the cv.  相似文献   

10.
Decline of newly planted, grafted grapevines is a serious viticultural problem worldwide. In the Riverina (New South Wales, Australia), characteristic symptoms include low fruit yields, very short shoots and severely stunted roots with black, sunken, necrotic lesions. To determine the cause, roots and wood tissue from affected plants in 20 vineyards (Vitis vinifera cv. Chardonnay grafted to V. champini cv. Ramsey rootstock) were assayed for microbial pathogens. Ilyonectria spp. (I. macrodidyma or I. liriodendra, producers of phytotoxin brefeldin A, BFA, and cause of black foot disease of grapevines) and Botryosphaeriaceae spp. (predominantly Diplodia seriata) were isolated from rootstocks of 100 and 95% of the plants, respectively. Togninia minima and Phaeomoniella chlamydospora (cause of grapevine Petri disease) were isolated from 13 and 7% of affected plants, respectively. All Ramsey rootstock stems of grafted plants sampled from a supplier nursery were infected with Ilyonectria spp. and D. seriata. Diplodia seriata, but not Ilyonectria spp., was also isolated from 25% of canes sampled from the rootstock source block. Root inoculation of potted, disease‐free Chardonnay plants with Ilyonectria isolates from diseased vineyards caused typical disease symptoms, while co‐inoculation with Botryosphaeriaceae spp. increased disease severity. This is the first study to show that a major cause of young grapevine decline can be sequential infection by Botryosphaeriaceae from rootstock cuttings and Ilyonectria spp. from nursery soil. Although the Petri disease fungi were less common in young declining grafted grapevines in the Riverina, they are likely to contribute to the decline of surviving plants as they mature.  相似文献   

11.
Petri disease of grapevine is primarily caused by Phaeomoniella chlamydospora. This pathogen affects mostly young grapevines, but is also implicated in esca disease of older grapevines. Little is known about the disease cycle of this fungus. Infected propagation material was identified as a major means of dissemination of the pathogen. Recently, the pathogen was also detected from soil in South Africa and airborne conidia have been found in vineyards. The aim of this study was to use a molecular detection technique to test different samples collected from nurseries in South Africa at different nursery stages for the presence of P. chlamydospora. A one-tube nested-PCR technique was optimised for detecting P. chlamydospora in DNA extracted from soil, water, callusing medium and grapevine wood. The one-tube nested-PCR was sensitive enough to detect as little as 1 fg of P. chlamydospora genomic DNA from water and 10 fg from wood, callusing medium and soil. PCR analyses of the different nursery samples revealed the presence of several putative 360 bp P. chlamydospora specific bands. Subsequent sequence analyses and/or restriction enzyme digestions of all 360 bp PCR bands confirmed that all bands were P. chlamydospora specific, except for five bands obtained from callusing media and one from water. Phaeomoniella chlamydospora was positively detected in 25% of rootstock cane sections collected from mother blocks, 42% of rootstock cuttings and 16% of scion cuttings collected during grafting, 40% of water samples collected after pre-storage hydration, 67% of water samples collected during grafting, 8% of callusing medium samples and 17% of soil samples collected from mother blocks. These media can therefore be considered as possible inoculum sources of the pathogen during the nursery stages.  相似文献   

12.
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   

13.
Phaeomoniella chlamydospora and wood-rotting basidiomycete fungi, namely Fomitiporia spp., are known esca pathogens. However, the effect of their mixed infections and the sequence of infection on disease development is unclear. To determine the effects of single and co-inoculations on symptoms, potted Vitis vinifera ‘Crimson Seedless’ was inoculated with P. chlamydospora either alone or in combination with one of four basidiomycetes: Coprinellus radians, Fomitiporia langloisii, F. polymorpha and the novel species Tropicoporus texanus. Basidiomycetes were isolated from vines with foliar symptoms of esca in California and Texas. In sequential co-inoculations, the effects of different sequences of infection (P. chlamydospora first, basidiomycete 6 months later; and vice versa) were tested, compared to simultaneous co-inoculations. Plants inoculated with P. chlamydospora either alone or in combination with a basidiomycete (in any sequence) did not differ significantly in the length of black-streaking lesions. In plants inoculated only with a basidiomycete, the appearance of large brown lesions, coupled with the absence of this wood symptom from control plants, suggests that C. radians, F. langloisii and T. texanus are pathogenic. Foliar symptoms resembling those of esca in the field (marginal and/or interveinal scorching, combined with red and/or yellow discoloration) were statistically more frequent among plants inoculated with F. polymorpha or T. texanus, either simultaneously or following P. chlamydospora, compared to single inoculations. Sequential co-inoculations of a basidiomycete before or after P. chlamydospora were associated with similar lesion lengths, suggesting that basidiomycetes may not require infection by P. chlamydospora in order to extensively colonize the wood.  相似文献   

14.
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 T. harzianum isolate T77 and the two T. atroviride 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 N. parvum 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 E. lata, N. australe, N. parvum and Phaeomoniella chlamydospora were inhibited by 6PP in a concentration‐dependent manner. The results show that the presence of N. parvum 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   

15.
In this study, 18 microsatellite loci were used to examine the genetic structure and mode of reproduction of Phaeomoniella chlamydospora, the fungus that causes Petri disease of grapevine and is involved in another grapevine disease, esca. A total of 60 southeastern Australian isolates were tested and compared with 64 isolates from southern France. The French population possessed relatively high genotypic diversity (G = 29·2) whilst the Australian population showed low genotypic diversity (G = 11·1), consistent with a limited founder population. Haplotypes from four different grapevine cultivars were not significantly differentiated (Φpt values effectively zero). Likewise, genetic differentiation of haplotypes from different regions within each country was not significant, although small but significant genetic differentiation (9%) was identified between Australia and France. Based on bootstrapped cluster analysis, there did not appear to be any genetic groups within the overall sample of isolates. Significant linkage disequilibrium identified in both countries, together with overrepresented, widespread identical haplotypes, indicated limited genetic recombination and a largely clonal structure consistent with the absence of an observed sexual cycle in this species.  相似文献   

16.
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   

17.
The effects of Glomus intraradices, Pseudomonas alcaligenes and Bacillus pumilus on the root-rot disease complex caused by the root-knot nematode Meloidogyne incognita and the root-rot fungus Macrophomina phaseolina in chickpea was assessed by quantifying differences in the shoot dry mass, pod number, nodulation, and shoot content of chlorophyll, nitrogen, phosphorus and potassium. Inoculation of plants with G. intraradices, P. alcaligenes and B. pumilus alone and in combination significantly increased shoot dry mass, pod number, and content of chlorophyll, nitrogen, phosphorus and potassium in plants inoculated with pathogens over that in the uninoculated control plants. P. alcaligenes caused a greater increase in shoot dry mass, pod number, chlorophyll, nitrogen, phosphorus and potassium in plants with pathogens than did G. intraradices or B. pumilus. Combined application of G. intraradices, P. alcaligenes and B. pumilus to plants inoculated with pathogens caused a greater increase in shoot dry mass, pod number, nitrogen, phosphorus, and potassium than did an application of P. alcaligenes plus B. pumilus or of G. intraradices plus B. pumilus. Root colonization by G. intrardices was high when used alone, while inoculation with the pathogens reduced root colonization by G. intraradices. In the presence of P. alcaligenes and B. pumilus, root colonization by G. intraradices increased. In plants inoculated with just one antagonist, P. alcaligenes reduced galling and nematode multiplication the most, followed by G. intraradices, then B. pumilus. The greatest reduction in galling, nematode multiplication and root-rot was observed when both bacterial species and G. intraradices were applied together.  相似文献   

18.
Brown leaf spot disease caused by Cylindrocladium was found on Howea belmoreana on Hachijojima Island, Tokyo, Japan, in December 2001. Typical symptoms were incited after artificial inoculation. A culture of white mycelia, isolated from leaf spot symptoms, produced reddish perithecia of a nectriaceous fungus. Based on morphological and molecular analyses, this fungus was identified as Calonectria ilicicola (anamorph: Cylindrocladium parasiticum). Pathogenicity of this fungus on five plants cultivated on Hachijojima Island was confirmed by artificial inoculation. This report is the first on Cylindrocladium brown leaf spot of H. belmoreana caused by C. ilicicola (anamorph: Cy. parasiticum).  相似文献   

19.
We have examined the effect of Pen, an aqueous extract of the dry mycelium of Penicillium chrysogenum, on plant–pathogen interactions. Pen controlled a broad range of pathogens on several crop plants under greenhouse and field conditions. Pen protected grapevine from downy and powdery mildew (caused by Plasmopara viticola and Uncinula necator), tomato from early blight (caused by Phytophthora infestans), onion from downy mildew (Peronospora destructor) and apple trees from apple scab (caused by Venturia inaequalis) to a similar extent as fungicides such as copper and sulphur or well-known inducers such as benzothiadiazole or β-aminobutyric acid. Pen had no major direct fungicidal effect and is thus supposed to protect plants by activating their defense mechanisms. The raw material for extraction of Pen was available in constant quality, a prerequisite for commercial application. Under certain conditions, Pen caused phytotoxic side effects. The symptoms mostly consisted of small necrotic spots or, more rarely, of larger necrotic areas. The development of the symptoms was dependent on several parameters, including concentration of Pen, the number of applications, the persistence on the plant tissue, the plant species and variety and environmental conditions. In grapevine, a partially purified fraction of Pen was much less toxic than the crude Pen extract, but protected the plants to a similar extent against P. viticola. Our data show that Pen has interesting and unique properties as a plant protection agent, but more research is needed to further reduce its phytotoxic side effects.  相似文献   

20.
Barley leaf rust resistance gene Rph7, derived from barley accession Cebada Capa, is the most effective R-gene for resistance to Puccinia hordei. Virulence for this gene was known in the USA, Israel and Morocco but not yet in Europe. We found an unexpected leaf rust infection in the field at Córdoba, Spain in 2004 on Rph7 carrying lines. This virulence for Rph7 was confirmed in growth chamber experiments, being the first report of Rph7 virulence in European populations of P. hordei. A collection of 680 barley accessions was screened for resistance against this new isolate. Twelve accessions showed segregation with individual plants showing resistance based on hypersensitivity (low infection type). These individual resistant plants were selected and grown in the greenhouse to obtain seeds.  相似文献   

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