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1.
大豆锈病研究现状与进展 总被引：4，自引：0，他引：4
大豆锈病近年在东南亚、南美洲发展迅速,对大豆生产威胁越来越大,尤其2004年11月登陆美国大陆,更引起大豆研究者、大豆生产国和进口国的极大关注。本文介绍了近年国际上大豆锈病的研究进展,主要包括大豆锈病的发现、地理分布、病原、症状、寄主范围、病原菌生理分化和防治技术研究等。 相似文献
2.
ABSTRACT Temperature is a critical factor in plant disease development. As part of a research program to determine how specific environmental variables affect soybean rust, we determined temperature effects on urediniospore germination and germ tube growth of four isolates of Phakopsora pachyrhizi, one each from Brazil, Hawaii, Taiwan, and Zimbabwe, and an isolate of P. meibomiae from Puerto Rico, collected over a 25-year period. Also compared were the effects of temperature during a night dew period on initiation of disease by the P. pachyrhizi isolates. All variables were fit to a nonlinear beta function with temperature as the independent variable. Minimum, maximum, and optimum temperatures, along with shape parameters of the beta function for each variable, were statistically analyzed. All Phakopsora isolates behaved similarly as to how temperature affected urediniospore germination, germ tube growth, and initiation of disease. The results suggest that P. pachyrhizi has changed little in the past few decades with respect to how it responds to temperature and that previously collected research data continues to be valid, simplifying the development of soybean rust disease models. 相似文献
3.
Effects of Simplicillium lanosoniveum on Phakopsora pachyrhizi, the soybean rust pathogen, and its use as a biological control agent 总被引：1，自引：0，他引：1
The fungus Simplicillium lanosoniveum was isolated from soybean leaves infected with Phakopsora pachyrhizi, the soybean rust pathogen, in Louisiana and Florida. The fungus did not grow or become established on leaf surfaces until uredinia erupted, but when soybean rust signs and symptoms were evident, S. lanosoniveum colonized leaves within 3 days and sporulated within 4 days. Development of new uredinia was suppressed by about fourfold when S. lanosoniveum colonized uredinia. In the presence of S. lanosoniveum, uredinia became increasingly red-brown, and urediniospores turned brown and germinated at very low rates. Assays using quantitative real time polymerase chain reaction revealed that the fungus colonized leaf surfaces when plants were infected with P. pachyrhizi, either in a latent stage of infection or when symptoms were present. However, when plants were inoculated before infection, there was no increase of DNA of S. lanosoniveum, suggesting that the pathogen must be present in order for the antagonist to become established on soybean leaf surfaces. We documented significantly lower amounts of DNA of P. pachyrhizi and lower disease severity when soybean leaves were colonized with S. lanosoniveum. These studies documented the mycophilic and disease-suppressive nature of S. lanosoniveum. 相似文献
4.
For over 30 years, it has been known that Phakopsora pachyrhizi is unusual in that it penetrates from urediniospores directly through the leaf cuticle without entering stomates. This unusual mode of penetration suggests that disease resistance mechanisms might exist for soybean rust that do not exist for most rust diseases. As a result, we decided to conduct a histological study using transmission electron microscopy to further elucidate the mechanisms of penetration and early establishment of P. pachyrhizi in soybean leaves. Based on our study, it was concluded that P. pachyrhizi utilizes primarily mechanical force, perhaps with the aid of digestive enzymes, to penetrate the cuticle on the leaf surface. However, the lack of deformation lines in micrographs indicated that digestive enzymes, without mechanical force, are used by the penetration hypha to penetrate the outer and inner epidermal cell walls. Digestive enzymes, again indicated by the lack of deformation lines, are used by haustorial mother cells to breach the walls of mesophyll cells to form haustoria. The possibility exists for eventual determination of the precise roles of pressure and digestive enzymes in the development of soybean rust and elucidation of some of the determinants of resistance and susceptibility to this important plant disease. 相似文献
5.
Shiro KUNINAGA Donald E CARLING Toru TAKEUCHI Ryozo YOKOSAWA 《Journal of General Plant Pathology》2000,66(1):2-11
Genetic diversity among 51 isolates of Rhizoctonia solani AG-3, representing potato and tobacco populations, was inferred from the sequences of the internal transcribed spacer (ITS)
and 5.8S ribosomal RNA (rRNA) gene. The 5.8S rDNA sequence was completely conserved not only in AG-3, but across all the AG
isolates examined, whereas the rDNA-ITS sequence was found to be variable among the isolates. The nucleotide sequence similarity
in the ITS 1 region was high (96-100%) for isolates within each of the two populations, but was 91-92% for isolates from different
populations. The AG-3 isolates had 56 to 91% sequence similarities in the ITS 1 region with R. solani isolates of the other AGs. Phylogenetic analysis based on the ITS-5.8S rDNA sequence data indicated that the different populations
in AG-3 are distantly related to each other. Genetic divergence between the two populations was also supported by the results
of DNA-DNA hybridization studies. This study suggests that AG-3 consists of two genetically isolated groups corresponding
to separate subgroups: AG-3 PT (potato type) and AG-3 TB (tobacco type). Specific primer sets for the detection of the two
AG-3 subgroups were developed from the aligned rDNA-ITS sequences.
Received 22 April 1999/ Accepted in revised form 2 July 1999 相似文献
6.
ABSTRACT Puccinia spp. are widespread pathogens of cereals and grasses that annually cause significant yield losses worldwide, especially in barley, oat, and wheat. Urediniospore morphology and early symptom development have limited usefulness for distinguishing Puccinia spp. Therefore, we developed real-time polymerase chain reaction assays for rapid detection of the four rust pathogen species, Puccinia graminis (Pers.:Pers.), P. striiformis (Westend.), P. triticina (Eriks.), and P. recondita (Roberge ex Desmaz.). Duplex assays were constructed for the nuclear rDNA gene, using the variable internal transcribed spacer 1 (ITS1) region to distinguish between species, and the conserved 28S region as an internal control. Species-specific ITS1 primer/probe sets were highly specific and could detect <1 pg of DNA. The species-specific primer/probe sets showed positive results over a linear range of DNA five orders of magnitude or greater. Specificity of the assays was tested using multiple collections representing a range of races and formae speciales within a species. Additionally, assay specificity was evaluated by testing a range of other grass rust pathogens, as well as other fungi. The 28S primer/probe combination was successful in detecting all Puccinia spp. tested within the duplex assays, validating the integrity of each assay. Finally, the assays were used to identify unknown rust fungi infecting pasture grasses. 相似文献
7.
ABSTRACT A technique based on the polymerase chain reaction (PCR) was developed for the identification of Venturia nashicola using nucleotide sequence information of the ribosomal DNA region. The complete internal transcribed spacer (ITS) region of V. nashicola strains and phylo-genetically related species was amplified with the two universal ITS1 and ITS4 primers, sequenced, and digested with five restriction enzymes. The alignment of nucleotide sequences and analyses of digestion patterns indicated constant polymorphisms between V. nashicola and related species at nucleotides 126 and 127, which overlapped a TaqI restriction site. An oligonucleotide primer named A126 was designed for identifying this variable region. A primer set (A126 and ITS4) that allowed the amplification of a 391-bp DNA fragment within the ITS region by PCR was specific to V. nashicola when it was checked against fungal genomic DNAs of related fungi. This primer set was a good candidate for a species-specific reagent in a procedure for identification of V. nashicola by PCR. 相似文献
8.
ABSTRACT Pythium irregulare is a plant-pathogenic oomycete that causes significant damage to a variety of crops, including ornamentals and vegetables. Morphological as well as molecular studies have reported high levels of genetic diversity within P. irregulare sensu lato which has raised the question as to whether it is a single species or is actually a complex of morphologically similar (cryptic) species. In this study, we used amplified fragment length polymorphism (AFLP) fingerprinting and DNA sequence analysis of the internal transcribed spacer (ITS) region of the ribosomal genes (ITS region) and a portion of the mitochondrial cytochrome oxidase II gene and the spacer region between coxI and coxII to characterize 68 isolates of P. irregulare from the United States. The ITS sequence of a P. irregulare neotype at the CBS collection as well as ITS and coxII sequences for P. irregulare, P. spinosum, and P. sylvaticum from previous studies were included in our analysis. Cluster analysis identified a 19-isolate group (IR-II) that separated itself from the rest of the sample (IR-I). Population structure and sequence analyses supported the distinction of IR-I and IR-II and identified IR-II as P. irregulare sensu stricto. IR-I was designated Pythium sp. clade IR-I. Two insertion/deletion mutations and nine nucleotide substitutions in the ITS region and three in the sequence of coxII and the adjacent spacer region separated the two species. Additionally, they differed significantly (P > 0.01) in the frequency of 182 (77%) AFLP alleles. Gene flow results suggested that P. irregulare sensu stricto and Pythium sp. clade IR-I are cryptic species capable of exchanging favorable alleles (Nm = 0.72). 相似文献
9.
Norio Kondo Ayumi Notsu Shohei Fujita Hisanori Shimada Shigeo Naito 《Journal of General Plant Pathology》2005,71(6):414-417
Sequences of the internal transcribed spacer (ITS) region 1 were used to examine the phylogenetic relationships among races
of 19 isolates of Phytophthora vignae f. sp. adzukicola and between this forma specialis and three isolates of the closely related P. vignae f. sp. vignae. The ITS 1 sequences were highly conserved (> 98.7% similarity) among representatives of both formae speciales groups. The
results of this study indicate that P. vignae is a monophyletic group.
The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession nos. AB120062–AB120080
and AB120122 相似文献
10.
ABSTRACT Soybean rust, Phakopsora pachyrhizi, has been considered a threat to the production of the U.S. soybean, Glycine max. During the past decade, this disease gradually spread to Africa, South America, and recently to the United States. Previous soybean rust risk assessments with an assumption of availability of spores early in a season showed that weather conditions (dew and temperature) during a growing season, in general, are suitable for disease development in U.S. soybean-growing regions. Predicting the time of rust appearance in a field is critical to determining the destructive potential of rusts, including soybean rust. In this study, comparative epidemiology was used to assess likely rust incipient time in four locations within the U.S. Soybean Belt from south to north: Baton Rouge, LA; Charlotte, NC; Indianapolis, IN; and Minneapolis, MN. Temperature effects on the infection cycle of five rusts occurring in the Midwest were evaluated using a general disease model. The likely incipient times were examined with the modeling results. Among the rusts studied, early-appearing rusts had suitable conditions for development earlier in a season. However, a lag period of several weeks to more than 3 months was found from the time when conditions are suitable for a rust to develop or when hosts are available to the time when the rust was detected in fields. Length of the lag period differed among the rust species examined. If nature of long-distance dispersal is not significantly different among the rusts, implications of our study to the expected seasonal soybean rust incipience in fields lead to two possible scenarios: (i) average appearance time of soybean rust across the Soybean Belt should be somewhere between appearance times of common corn rust and southern corn rust, and (ii) with late appearance of the disease, late-planted soybean in the south has greater risk. 相似文献
11.
Kendrick MD Harris DK Ha BK Hyten DL Cregan PB Frederick RD Boerma HR Pedley KF 《Phytopathology》2011,101(5):535-543
ABSTRACT Asian soybean rust (ASR) is an economically significant disease caused by the fungus Phakopsora pachyrhizi. The soybean genes Rpp3 and Rpp?(Hyuuga) confer resistance to specific isolates of the pathogen. Both genes map to chromosome 6 (Gm06) (linkage group [LG] C2). We recently identified 12 additional soybean accessions that harbor ASR resistance mapping to Gm06, within 5 centimorgans of Rpp3 and Rpp?(Hyuuga). To further characterize genotypes with resistance on Gm06, we used a set of eight P. pachyrhizi isolates collected from geographically diverse areas to inoculate plants and evaluate them for differential phenotypic responses. Three isolates elicited different responses from soybean accessions PI 462312 (Ankur) (Rpp3) and PI 506764 (Hyuuga) (Rpp?[Hyuuga]). In all, 11 of the new accessions yielded responses identical to either PI 462312 or Hyuuga and 1 of the new accessions, PI 417089B (Kuro daizu), differed from all others. Additional screening of Hyuuga-derived recombinant inbred lines indicated that Hyuuga carries two resistance genes, one at the Rpp3 locus on Gm06 and a second, unlinked ASR resistance gene mapping to Gm03 (LG-N) near Rpp5. These findings reveal a natural case of gene pyramiding for ASR resistance in Hyuuga and underscore the importance of utilizing multiple isolates of P. pachyrhizi when screening for ASR resistance. 相似文献
12.
Molecular identification of Colletotrichum gloeosporioides causing yam anthracnose in Nigeria 总被引：2，自引：1，他引：2
M. M. Abang S. Winter † K. R. Green P. Hoffmann H. D. Mignouna G. A. Wolf 《Plant pathology》2002,51(1):63-71
Four forms of Colletotrichum representing three distinct virulence phenotypes were found associated with foliar anthracnose of yam in Nigeria: the highly virulent (= severity of disease) slow-growing grey (SGG); the moderately virulent fast-growing salmon (FGS); the weakly virulent fast-growing grey (FGG); and the moderately virulent fast-growing olive (FGO) morphotype. Isolates of the four forms were identified as C. gloeosporioides , based on morphology. The reaction of monoconidial cultures on casein hydrolysis medium (CHM), PCR-RFLP and sequence analysis of the internal transcribed spacer region of the ribosomal DNA (ITS1-5·8S-ITS2) were used to establish the identity of the yam anthracnose pathogen(s). All yam isolates were distinguished from C. acutatum by the absence of protease activity on CHM. On ITS PCR and enzymatic digestion of PCR products, all FGS, FGO and SGG isolates produced RFLP patterns identical to those of C. gloeosporioides reference isolates, while FGG isolates revealed unique ITS RFLP banding patterns. Sequence analysis of the ITS1 region and of the entire ITS region revealed that SGG, FGS and FGO isolates were highly similar (98–99% nucleotide identity) and showed 97–100% identity to C. gloeosporioides . Less than 93% similarity of these fungal isolates to reference C. acutatum and C. lindemuthianum isolates was observed. The molecular study confirmed that foliar anthracnose of yam is caused by C. gloeosporioides . While a high similarity was found among most C. gloeosporioides fungi from yam, isolates of the FGG form did not cluster with any previously described Colletotrichum species, and probably represent a distinct species. 相似文献
13.
ABSTRACT Diaporthe phaseolorum and Phomopsis longicolla isolates from soybean were examined using traditional mycological characteristics and molecular methods. Cultural characteristics including types of fruiting bodies and conidia were assessed for isolates collected from soybean stems and seeds. Cultures were identified as P. longicolla, D. phaseolorum var. caulivora, D. phaseolorum var. meridionalis, or D. phaseolorum var. sojae. Molecular markers for these groups were developed and analyzed using polymerase chain reaction restriction fragment length polymorphisms (PCR-RFLP) and DNA sequencing in the internal transcribed spacer (ITS) and the 5.8S ribosomal DNA. The ITS(4) and ITS(5) primers amplified PCR products for all isolates studied. Gel electrophoresis of undigested PCR products and DNA sequencing produced various fragment lengths including 604 bp for P. longicolla, 602 and 603 bp for D. phaseolorum var. caulivora, 603 bp for D. phaseolorum var. meridionalis, and from 597 to 609 bp for D. phaseolorum var. sojae. Digestion of these PCR products with enzymes AluI, HhaI, MseI, RsaI, and ScrFI resulted in distinct bands for identification of P. longicolla and the varieties of D. phaseolorum I. All P. longicolla, D. phaseolorum var. caulivora, and D. phaseolorum var. meridionalis isolates were distinguished using AluI and HhaI with RsaI or ScrFI. The banding patterns of D. phaseolorum var. sojae isolates were complex and were separated into 11 subgroups after digestion with AluI, HhaI, MseI, RsaI, and ScrFI. Phylogenetic analysis of 20 isolates of D. phaseolorum and P. longicolla based on the DNA sequence of the ITS region resolved six clades termed A, B, C, D, E, and F. Clade A included all sequenced D. phaseolorum var. caulivora isolates, two from Italy and one from the United States. Isolates in clade B were exclusively associated with D. phaseolorum var. meridionalis. Clades A and B formed a well-supported monophyletic group. Isolates in clades C, D, E, and F were morphologically defined as isolates of P. longicolla, D. phaseolorum var. sojae, and Diaporthe spp. The ITS sequences similarity of seven geographically diverse P. longi-colla isolates illustrated that P. longicolla isolates have a similar genetic background, with some affiliations to some D. phaseolorum var. sojae isolates. Morphological characteristics of the isolates along with the terminal clades of the ITS phylogeny suggest that P. longicolla is an individual species, D. phaseolorum var. caulivora and D. phaseolorum var. meridionalis are varieties of D. phaseolorum, and D. phaseolorum var. sojae is either several varieties of D. phaseolorum or possibly several distinct species. 相似文献
14.
本文采用传统形态学与分子生物学相结合的方法,对采自山西省窖藏马铃薯和薯蓣块茎中的短体线虫进行了种类鉴定。结果表明,从马铃薯块茎中分离出的短体线虫形态学特征与斯克里布纳短体线虫Pratylenchus scribneri一致,其SSU序列与P. scribneri美国群体相似性达99.8%。从薯蓣块茎中分离出的短体线虫形态学特征与咖啡短体线虫P. coffeae一致,其ITS序列与P. coffeae浙江群体相似性达98.8%。斯克里布纳短体线虫首次在我国马铃薯块茎中发现,咖啡短体线虫首次在山西省薯蓣块茎中发现。 相似文献
15.
16.
ABSTRACT Root and stem rot caused by Phytophthora sojae is one of the most destructive diseases of soybean (Glycine max) worldwide. P. sojae can survive as oospores in soil for many years. In order to develop a rapid and accurate method for the specific detection of P. sojae in soil, the internal transcribed spacer (ITS) regions of eight P. sojae isolates were amplified using polymerase chain reaction (PCR) with the universal primers DC6 and ITS4. The sequences of PCR products were aligned with published sequences of 50 other Phytophthora species, and a region specific to P. sojae was used to design the specific PCR primers, PS1 and PS2. More than 245 isolates representing 25 species of Phytophthora and at least 35 other species of pathogens were used to test the specificity of the primers. PCR amplification with PS primers resulted in the amplification of a product of approximately 330 bp, exclusively from isolates of P. sojae. Tests with P. sojae genomic DNA determined that the sensitivity of the PS primer set is approximately 1 fg. This PCR assay, combined with a simple soil screening method developed in this work, allowed the detection of P. sojae from soil within 6 h, with a detection sensitivity of two oospores in 20 g of soil. PCR with the PS primers could also be used to detect P. sojae from diseased soybean tissue and residues. Real-time fluorescent quantitative PCR assays were also developed to detect the pathogen directly in soil samples. The PS primer-based PCR assay provides a rapid and sensitive tool for the detection of P. sojae in soil and infected soybean tissue. 相似文献
17.
The origin and genetic diversity of the causal agent of Asian soybean rust,Phakopsora pachyrhizi,in South America 
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下载免费PDF全文 V. R. Jorge M. R. Silva E. A. Guillin M. C. M. Freire I. Schuster A. M. R. Almeida L. O. Oliveira 《Plant pathology》2015,64(3):729-737
A sequence‐based approach was used to investigate molecular genetic variations in Phakopsora pachyrhizi, an obligate biotrophic pathogen that causes Asian soybean rust. In Argentina, the samples came from uredinium‐bearing leaves taken from 11 soybean fields; in Brazil, the samples comprised urediniospores from leaves of 10 soybean genotypes that had been grown in three experimental stations during two growing seasons. PCR‐based cloning techniques were used to generate DNA sequences for two gene regions and alignments were supplemented with data from GenBank. A total of 575 sequences for the internal transcribed spacer region (18 ribotypes) and 160 partial sequences for a housekeeping gene encoding ADP‐ribosylation factor (10 haplotypes) were obtained. Ribotype accumulation curves predicted that about 20 bacterial clones would recover 5–6 ribotypes (c. 70–80% of the total molecular variation) per locality. The samples from the three experimental stations in Brazil displayed most (14 out of 16) ribotypes found worldwide; the lack of genetic structure and differentiation at a diverse geographic scale suggests that both local and distant sources provide airborne inoculum during disease establishment. Soybean genotypes with resistance genes for the Asian soybean rust did not decrease the molecular genetic variation of fungal populations. 相似文献
18.
本研究采用DAS ELISA、IC RT PCR及序列测定方法,对加拿大进境大豆种子进行菜豆荚斑驳病毒（Bean pod mottle virus, BPMV）和大豆花叶病毒（Soybean mosaic virus,SMV）检测,结果表明,BPMV的DAS ELISA和IC RT PCR检测结果均为阳性,且PCR扩增产物序列与已报道的BPMV基因序列相似性达97%以上,而SMV的DAS ELISA和IC RT PCR检测结果都为阴性。综合血清学、分子生物学检测结果,确认该批大豆携带有菜豆荚斑驳病毒。 相似文献
19.
A species-specific, nested polymerase chain reaction (PCR)-based detection assay, using two primer sets designed from the rRNA ITS region, was developed for Puccinia psidii . Detection sensitivities of one urediniospore alone, or one or two urediniospores in the presence of pollen or leaf tissues, respectively, were observed. The assay reliably, accurately and sensitively detected the rust from naturally infected, geographically widespread eucalypt and fruit tree plantation and nursery species from diverse tissues types (e.g. leaves, flowers, fruits, pollen, seeds and woody material) including symptomless or cryptically contaminated plants or plant tissue. Independent testing in Brazil and Australia demonstrated the international inter-laboratory transferability of the P. psidii assay required for germplasm screening, disease monitoring and quarantine and incursion management, towards which the assay has already been employed. 相似文献
20.
Bilodeau GJ Lévesque CA de Cock AW Duchaine C Brière S Uribe P Martin FN Hamelin RC 《Phytopathology》2007,97(5):632-642
ABSTRACT Sudden oak death, caused by Phytophthora ramorum, is a severe disease that affects many species of trees and shrubs. This pathogen is spreading rapidly and quarantine measures are currently in place to prevent dissemination to areas that were previously free of the pathogen. Molecular assays that rapidly detect and identify P. ramorum frequently fail to reliably distinguish between P. ramorum and closely related species. To overcome this problem and to provide additional assays to increase confidence, internal transcribed spacer (ITS), beta-tubulin, and elicitin gene regions were sequenced and searched for polymorphisms in a collection of Phytophthora spp. Three different reporter technologies were compared: molecular beacons, TaqMan, and SYBR Green. The assays differentiated P. ramorum from the 65 species of Phytophthora tested. The assays developed were also used with DNA extracts from 48 infected and uninfected plant samples. All environmental samples from which P. ramorum was isolated by PARP-V8 were detected using all three real-time PCR assays. However, 24% of the samples yielded positive real-time PCR assays but no P. ramorum cultures, but sequence analysis of the coxI and II spacer region confirmed the presence of the pathogen in most samples. The assays based on detection of the ITS and elicitin regions using TaqMan tended to have lower cycle threshold values than those using beta-tubulin and seemed to be more sensitive. 相似文献