首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 46 毫秒
1.
Oat stem rust, caused by Puccinia graminis f. sp. avenae (Pga), is one of the most severe diseases of oats worldwide. Population studies are scarce for this pathogen, mainly due to the lack of polymorphic molecular markers suitable for genetic analysis. In this study, an Australian Pga isolate was sequenced, the abundance of simple sequence repeats (SSRs) was determined and PCR‐based polymorphic markers suitable for genetic diversity analysis were developed. The amplification of 194 primer pairs was initially assessed using a set of 12 isolates of different cereal rust species and their formae speciales. A high frequency of cross‐species amplification was observed for most markers; however, 36 SSRs were diagnostic for P. graminis only. A subset of 19 genome‐derived SSRs were deemed useful for genetic diversity analysis of Pga and were assessed on 66 Pga isolates from Australia, Brazil and Sweden. Brazilian and Australian isolates were characterized by one and two predominant clonal lineages, respectively. In contrast, the Swedish isolates, previously shown to undergo sexual recombination, were highly diverse (nine distinct genotypes out of 10 isolates) and divided into two subpopulations. The genome‐derived SSR markers developed in this study were well suited to the population studies undertaken, and have diagnostic capabilities that should aid in the identification of unknown rust pathogen species.  相似文献   

2.
Stem rust, caused by Puccinia graminis, is a destructive group of diseases. The pathogen uses Berberis species as alternate hosts to complete its life cycle. B. vulgaris and the endemic species B. hispanica and B. garciae are present in Spain. The objective of this study was to investigate the functionality of the indigenous barberry as alternate hosts. Field surveys were conducted in 2018 and 2019 in Huesca, Teruel and Albacete provinces of Spain. Aecial samples on barberry were analysed via infection assays and DNA analysis. B. garciae was predominant in Huesca and Teruel provinces, often found in the field margins of cereal crops. Aecial infections on B. garciae were observed in May and uredinial infections on cereal crops in June. Scattered B. hispanica bushes were occasionally found near cereal crops in Albacete, where aecial infections on B. hispanica were observed in June when most cereal crops were mature. Infection assays using aeciospores resulted in stem rust infections on susceptible genotypes of wheat, barley, rye and oat, indicating the presence of the sexual cycle for P. graminis f. sp. tritici, f. sp. secalis and f. sp. avenae. Sequence analyses from aecial samples supported this finding as well as the presence of Puccinia brachypodii. This study provides the first evidence that indigenous Berberis species play an active role in the sexual cycle of P. graminis under natural conditions in Spain.  相似文献   

3.
Berlin A  Djurle A  Samils B  Yuen J 《Phytopathology》2012,102(10):1006-1012
Puccinia graminis, the causal agent of stem rust, was collected from its alternate host barberry (Berberis spp.) and two different uredinial hosts, oats (Avena sativa) and rye (Secale cereale). The samples were analyzed using 11 polymorphic simple sequence repeat (SSR) markers. There were large differences between fungal populations on oats (P. graminis f. sp. avenae) and rye (P. graminis f. sp. secalis), and the genetic variation within the different formae speciales was also high. It was possible to distinguish between the two formae speciales on barberry. Additional genotypic groups not present in the field samples from oats and rye were also identified on barberry. Our results confirm the importance of barberry in maintaining the populations of P. graminis in Sweden and the importance of the sexual stage for the survival of the pathogen.  相似文献   

4.
Wheat stem rust, caused by the fungus Puccinia graminis f. sp. tritici (Pgt), is a notoriously damaging disease of wheat and barley. Pgt requires two hosts to complete its lifecycle; undergoing asexual reproduction on cereal crops and completing sexual reproduction on Berberis spp. The latter stage of its lifecycle is of particular importance in temperate regions such as western Europe, where asexual urediniospores are unable to survive cold winter weather. In the past, the crucial role of Berberis in the lifecycle of stem rust led to intensive eradication campaigns, initially carried out by farmers in the face of hostile scientific opinion. In the United Kingdom, common barberry (Berberis vulgaris) is today a relatively rare plant. Stem rust is, however, currently experiencing a resurgence; at the same time, there has been a general increase in the prevalence of barberry and an upsurge in its planting which, in the United Kingdom, is associated with attempts to encourage the endangered barberry carpet moth (Pareulype berberata). This article situates current developments within a broader chronological framework, examining changing attitudes towards barberry and rust in England in the past and the history of the plant's use and cultivation. It assesses how widespread B. vulgaris really was in the environment historically, and thus the scale of its eradication. We suggest that Berberis was never widely established as an archaeophyte in the United Kingdom. Current attempts to re-establish it are based on a misunderstanding of the plant's historical status and could potentially pose a serious threat to food security.  相似文献   

5.
  相似文献   

6.
Stripe rust of wheat caused by Puccinia striiformis f. sp. tritici has recently become a production problem on wheat in Alberta, Canada, and stripe rust of barley caused by P. striiformis f. sp. hordei occurs regularly. A total of 261 isolates of P. striiformis were collected from wheat, barley, Hordeum jubatum and triticale plants in Alberta, Canada from 2007 to 2012, and compared to isolates from other provinces and the USA. The genetic diversity of the pathogen was assessed using 11 simple sequence repeat (SSR) markers and by examining a length polymorphism in the ribosomal DNA (rDNA) intergenic spacer 1 (IGS1) region. A total of 28 SSR genotypes were detected within Alberta. The 13 genotypes common on wheat (P. striiformis f. sp. tritici) were distinct from the 15 genotypes common on barley (P. striiformis f. sp. hordei). Four SSR genotypes, two within each forma specialis, represented 85% of the isolates recovered. Genotypic diversity was low, population genetic analysis indicated a clonal structure, and the genotypes were widely dispersed. In both formae speciales, the dominant genotype varied between years. The second most common P. striiformis f. sp. hordei genotype was found to be more closely related to older P. striiformis f. sp. tritici genotypes from the USA than to other P. striiformis f. sp. hordei genotypes.  相似文献   

7.
The fungus Puccinia coronata Corda. is the causal agent of crown rust on oats (Avena sativa) and grasses and the disease is a major problem in oat production causing devastating yield losses. The population biology of P. coronata in oat fields and on the aecial host in central Sweden was studied to get a deeper understanding of the role of the aecial hosts in the epidemiology of the disease. Samples were collected from the aecial hosts common buckthorn (Rhamnus cathartica) and alder buckthorn (Frangula alnus), and three adjacent spring oat (Avena sativa) fields. Microsatellite markers were used to evaluate the relationships between populations sampled from the different hosts. According to our results F. alnus can be excluded as a part of the oat crown rust disease cycle. The results further show that samples collected from the aecial host were genetically separate from the population sampled in adjacent oat fields. Concurrently, the genotypic variation of P. coronata observed within oat fields was high. No population differentiation was observed within or between samples collected from different fields within the region, suggesting that airborne spores from other than the sampled specimens of the aecial hosts were contributing to the genetic diversity of P. coronata f. sp. avenae in the selected oat fields.  相似文献   

8.
Six heterocyclic alkylating agents were synthesized and examined for activity against the oat stripe pathogenPyrenophora avenae on agar plates and against the barley powdery mildew fungusBlumeria graminis f.sp.hordei on barley seedlings. Radial growth ofP. avenae was not significantly affected by any of the compounds, but four of them,α,α-bis[4,7-bis(2-chloroethyl)-1,4,7-triazacyclononane]-para-xylene[3], 1,4,8,11-tetra(2-chloroethyl)-1,4,8,11-tetraazacyclotetradecane[4], 8,11-bis(2-chloroethyl)-1,4,8,11-tetraaza-5,7-oxocyclotetradecane[5] and 7,16-bis(2-chloroethyl-1,4,10,13-tetraoxa-7,16-diazaoctadecane[6], gave significant reductions in biomass ofP. avenae grown in liquid culture and in powdery mildew infection on barley when used at 25μM. Polyamine biosynthesis was examined by following the incorporation of labeled ornithine into polyamines inP. avenae. The four compounds3–6 which reduced mildew infection all reduced the flux of label through to the polyamines inP. avenae. Whether the reductions in mildew infection caused by these compounds is related to reduced formation of polyamines is not known and awaits investigation. http://www.phytoparasitica.org posting May 22, 2005.  相似文献   

9.
An isolate of Puccinia coronata f.sp. avenae with virulence against the oat crown rust resistance gene Pc94 was discovered in oat fields in Córdoba, Spain. In order to identify alternative sources of resistance to this virulent isolate, a collection of 159 Avena accessions, including 107 A. sativa and 29 A. byzantina landraces and 23 commercial A. sativa and A. strigosa cultivars, was screened. Eight resistant landraces and four cultivars were selected according to macroscopic assessment to further characterize the operative defence mechanisms. Histological studies showed a range of defence mechanisms, acting alone or in combination, which impeded fungal development at different stages. Some accessions allowed reduced fungal growth before mesophyll penetration. In others, the fungus was arrested at the penetration stage by mesophyll cell wall strengthening and/or papilla deposition. Mesophyll cells of several accessions were penetrated by the fungus, but then the hypersensitive response (HR) leading to cell death hampered fungal development. In some cases cell death was very fast and colonies aborted early, whereas in other cases necrosis was observed later and associated with numerous secondary hyphae, suggesting a slow HR. Characterization of defence mechanisms will be useful for breeding programmes and for further cellular and molecular studies to unravel the bases of resistance. Commonalities with the resistance of the same oat collection to powdery mildew are discussed.  相似文献   

10.
青海东部小麦条锈菌转主寄主小檗资源调查与鉴定   总被引：1，自引：0，他引：1  
 青海省是中国小麦条锈病的重要流行区。研究证实小檗是小麦条锈菌的转主寄主。然而,关于青海省分布的小檗能否作为小麦条锈菌转主寄主鲜有报道。本研究对青海东部的小檗资源进行调查,并对该地区小檗能否作为小麦条锈菌转主寄主进行了室内人工鉴定。结果表明:有10种小檗在青海东部常见且分布广泛,其中匙叶小檗、置疑小檗、松潘小檗、甘肃小檗和近似小檗,是小麦条锈菌的转主寄主小檗的新种类。本研究对进一步研究青海东部条锈菌有性生殖与毒性变异和小麦条锈病的流行奠定了基础。  相似文献   

11.
Evaluation of oat crown rust resistance is usually based on visual assessment of disease severity or infection types. Visual assessment is subjective, prone to rater bias and requires expert knowledge. PCR-based quantitative assays can overcome challenges associated with visual assessment. New TaqMan primers and probes were designed from Puccinia coronata f. sp. avenae (Pca) sequences. The primer–probe sets were specific to Pca, amplified using as little as 0.5 pg fungal DNA (fDNA) and allowed for scaling to variation in sample total DNA quantity. The quantitative PCR (qPCR) assay was validated using oat recombinant inbred lines (RILs) from the Provena × 94197A1-9-2-2-2-5 cross evaluated under a controlled environment. For comparison with fDNA load, inoculation with the Pca race LCBB provided segregation data on the hypersensitive response, while Pca race LSLG provided data on segregation for reduced pustule number. fDNA content was positively correlated with both pustule number and infection type (IT). Composite interval mapping identified two quantitative trait loci (QTLs) on oat linkage groups Mrg12 and Mrg20 using visual and qPCR assessments (pustule number, IT and fDNA). In this study a qPCR assay method that can be used to assess the relative resistance of oat to crown rust was refined and validated, and single nucleotide polymorphisms (SNPs) closely linked with two QTLs derived from the crown rust resistant line 94197A1-9-2-2-2-5 were identified.  相似文献   

12.
The objective of this study was to determine whether genetically differentiated groups of Puccinia triticina are present in Europe. In total, 133 isolates of P. triticina collected from western Europe, central Europe and Turkey were tested for virulence on 20 lines of wheat with single leaf rust resistance genes, and for molecular genotypes with 23 simple sequence repeat (SSR) markers. After removal of isolates with identical virulence and SSR genotype within countries, 121 isolates were retained for further analysis. Isolates were grouped based on SSR genotypes using a Bayesian approach and a genetic distance method. Both methods optimally placed the isolates into eight European (EU) groups of P. triticina SSR genotypes. Seven of the groups had virulence characteristics of isolates collected from common hexaploid wheat, and one of the groups had virulence characteristics of isolates from tetraploid durum wheat. There was a significant correlation between the SSR genotypes and virulence phenotypes of the isolates. All EU groups had observed values of heterozygosity greater than expected and significant fixation values, which indicated the clonal reproduction of urediniospores in the overall population. Linkage disequilibria for SSR genotypes were high across the entire population and within countries. The overall values of RST and FST were lower when isolates were grouped by country, which indicated the migration of isolates within Europe. The European population of P. triticina had higher levels of genetic differentiation compared to other continental populations.  相似文献   

13.
Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the major fungal pathogens of wheat. A new pathotype was introduced to Australia in 2002 and several derivative pathotypes were detected in subsequent seasons. It has been suggested that the severity of stripe rust outbreaks in Australia since 2002 could be as a result of traits other than virulence in the pathogen population. This study was conducted to investigate the hypothesis that the stripe rust pathogen population dominant in Australia since 2002 was better adapted to warm temperature conditions compared to previous pathogen populations. Sixteen pathotypes were selected to examine the influence of two contrasting temperature regimes during the 24 h incubation (10°C and 15°C) and the subsequent post‐inoculation (17°C and 23°C) periods on latent period and infection efficiency on four susceptible wheat cultivars. In addition, the effect of two contrasting incubation temperatures on urediniospore germination was examined. The results indicated that pathotypes of P. striiformis f. sp. tritici detected after 2002 did not show evidence of adaptation to high temperatures, which suggests that other factors contributed to the observed increased aggressiveness.  相似文献   

14.
Puccinia coronata was not previously described on Rhamnus spp. in Tunisia. Three sites in the northwest of Tunisia, where Rhamnus is reported to be abundant, were surveyed for the presence of pycnia and aecia of oat crown rust caused by Puccinia coronata f. sp. avenae. Two Rhamnus species (R. lycioides and R. alaternus) were encountered in the sites. Pycnia with viable pycniospores and aecia with viable aeciospores were found on R. lycioides. However, no characteristic structures of crown rust were found on R. alaternus. Aeciospores collected from leaves of R. lycioides were used to inoculate oat plants usually susceptible to oat crown rust. Typical uredinia containing oat crown rust urediniospores appeared on the leaves of these plants. Moreover, the sixteen Pc-gene differential oat lines, used by oat researchers to study the virulence pattern in oat crown rust populations, were artificially inoculated with aeciospores from R. lycioides. These inoculated lines showed resistance/susceptibility similar to the registered resistance level of these lines to crown rust under field conditions in Tunisia. These results indicate that R. lycioides, a common and endemic part of the vegetation in the northwest of Tunisia, is a new aecial host of oat crown rust. The aeciospores produced on this forest plant could constitute the source of the virulence diversity already detected via the Pc-gene line trials.  相似文献   

15.
In China, wheat stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most destructive diseases of wheat. The Longnan and Linxia regions in Gansu Province and Qinghai Province are the major over-summering regions for the pathogen and key epidemiological zones in Northwest China. Population genetic diversity and interregional long-distance spread of the wheat stripe rust pathogen in Northwest China were studied using SSR markers. The genetic diversity in the Longnan population was much higher than those in the Linxia and Qinghai populations. Therefore, the molecular data confirmed that the Longnan region is a center of genetic diversity for P. striiformis f. sp. tritici in Northwest China. The low genetic differentiation (Gst = 0.15) and the extensive gene flow (Nm = 1.37) were found among the three regions in Northwest China. The most important conclusion of this study is that the stripe rust inoculum in Qinghai can come from both Longnan and Linxia, but mainly from Longnan directly in the spring.  相似文献   

16.
Wheat stem rust, caused by Puccinia graminis f. sp. tritici, is a re-emerging disease, posing a threat to wheat production. In Spain, stem rust has been rarely detected since the 1970s, but infection was observed in wheat fields in 2018. We analysed six stem rust samples collected in Rota, Cádiz province and one from Monteagudo del Castillo, Teruel province. All the samples from Rota were typed as race TKTTF, whereas the sample from Monteagudo del Castillo, collected in a wheat field adjacent to barberry bushes, was typed as race TKHBK. This race has a unique and significant virulence combination that includes virulence to Sr31, Sr33, Sr53 and Sr59, and is avirulent to Rusty, a durum line developed for universal susceptibility to the wheat stem rust pathogen. TKHBK is the first race outside the Ug99 race group with virulence to Sr31 and the first known race with virulence to Sr59. Genotyping studies indicate that race TKHBK does not belong to the Ug99 or TKTTF race groups and constitutes a previously unknown lineage. Two hundred bread and durum wheat cultivars and breeding lines from Spain were evaluated against TKHBK, TKTTF, and six additional races. Resistance was observed to all the races evaluated. Molecular markers confirmed the presence of Sr7a, Sr24, Sr31, Sr38 and Sr57 in bread wheat, and Sr13 in durum wheat. The re-emergence of wheat stem rust in Spain and the occurrence of unique virulences underscore the need to continue surveying and monitoring this disease.  相似文献   

17.
小麦条锈菌有性生殖与毒性变异的研究进展   总被引：1，自引：0，他引：1  
小麦条锈病是由条形柄锈菌小麦专化型Puccinia striiformis f.sp.tritici Erikss.et Henn.引起的、最具毁灭性的小麦真菌病害之一,在全世界小麦种植的国家或地区均有发生,其流行常常导致小麦严重的产量损失。利用抗病品种是防治小麦条锈病最为经济、有效的措施。然而,由于病原菌毒性变异不断产生新小种,频繁导致品种抗病性"丧失",继而引发病害流行成灾。小麦条锈菌的有性阶段过去一直未被发现,有性生殖与条锈菌变异及其在病害发生中的作用研究一直处于空白状态。近年来,随着小麦条锈菌转主寄主的发现,国内外学者开展了相关的研究工作,取得了一系列重要的研究进展。本文综述了小麦条锈病的发生症状、病菌的生物学特性、转主寄主、有性生殖与条锈菌毒性变异、转主寄主在条锈病发生中的作用、影响有性生殖发生的因素等方面的最新进展,并展望了深入开展小麦条锈菌有性生殖的研究思路。  相似文献   

18.
This is the first genetic study reporting on the interaction and molecular mapping of resistance to the barley grass stripe rust pathogen (Puccinia striiformis f. sp. pseudo‐hordei, Psph) in common wheat. Seedlings of 638 wheat accessions were tested and it was determined that wheat is a near‐nonhost to Psph based on rare susceptibility observed in <2% of commercial cultivars and <5% of wheat landraces. As previously observed for P. striiformis f. sp. tritici (Pst), the Australian cultivar Teal was highly susceptible to Psph. In contrast, a selection of cv. Avocet carrying complementary resistance genes Yr73 and Yr74 (Avocet R; AvR) was resistant. The Teal × AvR (T/A) doubled haploid (DH) population was used to map resistance in AvR to Psph. Infection types on the T/A DH lines inoculated with Psph and Pst indicated that all DH lines carrying both Yr73 and Yr74 were also resistant to Psph; however, fewer DH lines were susceptible to Psph than expected, suggesting the resistance was more complex. QTL analysis using 9053 DArT‐Seq markers determined that resistance to Psph was polygenically inherited and mapped to chromosomes 3A, 3D, 4A and 5B. The 3DL and 5BL markers co‐located with Yr73 and Yr74, suggesting an overlap between host and non‐host resistance mechanisms.  相似文献   

19.
Simple sequence repeat (SSR) markers were used to classify 116 isolates of Phakopsora pachyrhizi, the cause of soyabean rust, collected from infected soyabean leaves in four agroecological zones in Nigeria. A high degree of genetic variation was observed within the sampled populations of P. pachyrhizi. Eighty‐four distinct genotypes were identified among three of the four agroecological zones. Nei’s average genetic diversity across geographical regions was 0·22. Hierarchical analysis of molecular variance showed low genetic differentiation among all populations of P. pachyrhizi. The majority (> 90%) of the genetic diversity was distributed within each soyabean field, while approximately 6% of the genetic diversity was distributed among fields within geographic regions. Low population differentiation was indicated by the low FST values among populations, suggesting a wide dispersal of identical genotypes on a regional scale. Phylogenetic analysis indicated a strictly clonal structure of the populations and five main groups were observed, with group II accounting for 30% of the entire population. Because of the asexual reproduction of P. pachyrhizi, single‐step mutations in SSR genotypes are likely to account for the genetic differences within each group.  相似文献   

20.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号