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ABSTRACT The complete sequence of the 7.07 Mb genome of the biological control agent Pseudomonas fluorescens Pf-5 is now available, providing a new opportunity to advance knowledge of biological control through genomics. P. fluorescens Pf-5 is a rhizosphere bacterium that suppresses seedling emergence diseases and produces a spectrum of antibiotics toxic to plant-pathogenic fungi and oomycetes. In addition to six known secondary metabolites produced by Pf-5, three novel secondary metabolite biosynthesis gene clusters identified in the genome could also contribute to biological control. The genomic sequence provides numerous clues as to mechanisms used by the bacterium to survive in the spermosphere and rhizosphere. These features include broad catabolic and transport capabilities for utilizing seed and root exudates, an expanded collection of efflux systems for defense against environmental stress and microbial competition, and the presence of 45 outer membrane receptors that should allow for the uptake of iron from a wide array of siderophores produced by soil microorganisms. As expected for a bacterium with a large genome that lives in a rapidly changing environment, Pf-5 has an extensive collection of regulatory genes, only some of which have been characterized for their roles in regulation of secondary metabolite production or biological control. Consistent with its commensal lifestyle, Pf-5 appears to lack a number of virulence and pathogenicity factors found in plant pathogens. 相似文献
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C. Aguayo J. Riquelme P. D. T. Valenzuela M. Hahn E. Silva Moreno 《Journal of General Plant Pathology》2011,77(4):230-238
We previously identified Bchex as a highly expressed gene during filamentous growth in Botrytis cinerea. The gene encodes the principal protein of the Woronin body and has been shown to seal septal pores in response to cellular
damage. In the present study, Southern blot analysis of genomic DNA indicated that the gene exists as a single copy in the
B. cinerea genome. The gene was differentially expressed during various developmental stages: expression was high in germinating conidia
and the mycelial stage and lower in resting conidia and the appressorial stage. For functional analyses, homologous recombination
was used to obtain a ΔBchex knockout mutant. Growth of the mutant was strongly reduced growth in complete medium and in defined media with sucrose, fructose
or pectin as the carbon source. After detached tomato leaves were inoculated with the Bchex mutant, lesion development was markedly reduced compared to the control, suggesting that Bchex participates in normal growth, germination and virulence of this fungus. 相似文献
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Experimentally evolved populations of the potato cyst nematode Globodera pallida allow the targeting of genomic footprints of selection due to host adaptation 
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下载免费PDF全文 D. Eoche‐Bosy J. Gauthier A. S. Juhel M. Esquibet S. Fournet E. Grenier J. Montarry 《Plant pathology》2017,66(6):1022-1030
In the current agronomical context of pesticide use reduction, deciphering the genetic bases of pathogen adaptation to plant defences is of major importance to improve durability of resistance. Indeed, knowledge of virulence gene frequencies in pathogen populations could allow the prediction of resistance durability before deployment. Globodera pallida is a major pest of potato crops for which a promising resistance QTL, GpaVvrn, has been identified in Solanum vernei. An experimental evolution study, in which G. pallida lineages evolved on resistant or susceptible potato genotypes for up to eight generations, previously showed that G. pallida was able to rapidly overcome GpaVvrn resistance. However, it was not known if enough genetic mixing occurred in these lineages to be able to detect islands of differentiation in a genome scan approach. Here, this question was investigated using 53 polymorphic microsatellite markers distributed along the genome and three different tests based on genetic differentiation and heterozygosity. Eight outlier loci were identified, indicative of genomic regions putatively involved in host adaptation. Several loci were identified by multiple detection methods and/or in two independent adapted lineages. Some candidate genomic regions identified also seemed to be involved in overcoming resistance to nematodes in a plant genotype harbouring the same resistance QTL in a different genetic background. These results validate the feasibility of a genome scan approach on biological material coming from short experimental evolution, and encourage the use of a high coverage genome scan by whole genome resequencing. 相似文献
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为明确帚枝霉属内生真菌Sarocladium brachiariae HND5菌株具体的抑菌活性物质,在全基因组测序数据的基础上,利用生物信息学对抑菌活性物质合成基因簇进行定位,通过聚类分析和系统发育树分析对基因簇合成产物进行鉴定,并通过基因缺失突变构建及代谢组分析确定具体的抑菌活性物质。结果显示,HND5菌株共含有7个非核糖体多肽合成酶(non-ribosomal peptide synthetase,NRPS)基因簇,聚类分析结果表明基因簇29合成产物为噬铁素,基因簇30合成产物为类环孢霉素类抗菌多肽;系统发育树结合生物信息学结果显示基因簇30合成产物与已知环孢霉素结构差异大,为一个新型非核糖体多肽;将基因簇30 NRPS基因缺失突变后,HND5菌株丧失抑菌活性;同野生型菌株相比,基因簇30 NRPS基因缺失突变体缺失一个分子量为887.54 Da的多肽类物质。表明HND5菌株的抑菌活性物质为一个分子量为887.54 Da的新型类环孢霉素非核糖体多肽,基因簇30负责该多肽的生物合成。 相似文献
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A. Marais L. Svanella‐Dumas M. Barone P. Gentit C. Faure G. Charlot A. Ragozzino T. Candresse 《Plant pathology》2012,61(1):195-204
The variability of Cherry capillovirus A (CVA) was analysed using a short, 275‐bp region of the viral RNA‐dependent RNA polymerase gene amplified by a polyvalent RT‐PCR assay. As for other members of the family Betaflexiviridae, CVA appears to show significant diversity, with an average pairwise nucleotide divergence of 9·4% between isolates in the analysed region. Phylogenetic analyses provide evidence for the existence of at least five clusters of CVA isolates, one of which is associated with noncherry hosts of the virus, providing evidence that transmission of CVA isolates between cherry and noncherry hosts is probably rare. Comparison of existing detection techniques using a panel of CVA isolates representative of the various phylogenetic groups indicated that dot‐blot hybridization assays show high polyvalence but may lack the sensitivity to detect CVA in some samples. On the other hand, available detection primers failed to amplify a wide range of CVA isolates. Partial genome sequencing of two divergent isolates allowed the identification of conserved genomic regions and the design of new primer pairs with improved polyvalence. These new primer pairs were used to develop PCR assays allowing the reliable detection of CVA isolates belonging to all phylogenetic clusters. 相似文献
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为科学利用化学感受蛋白（chemosensory protein,CSP）绿色防控褐飞虱Nilaparvata lugens,采用同源序列比对和基因克隆对褐飞虱CSP基因进行鉴定,利用基因组分析其CSP基因簇,通过酵母信号肽分泌验证系统验证褐飞虱CSP信号肽的活性。结果显示,共克隆了15个褐飞虱CSP基因,其中有4个CSP基因为新鉴定到的;共发现了2个CSP基因簇,均位于褐飞虱2号染色体上;14个CSP的N末端序列有较强的信号肽分泌活性,其中11个活性序列与SignalP-4.1预测的序列一致,另外3个CSP的活性序列比SignalP-4.1预测的序列长。 相似文献
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M. Bogale E.T. Steenkamp M.J. Wingfield B.D. Wingfield 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(3):369-378
Fusarium solani is a fungal pathogen that infects many different genera of plants. It represents one of the two Fusarium spp. commonly isolated from agricultural soils and plant tissues in Ethiopia. To determine the diversity of F. solani in Ethiopia, we studied 43 isolates using Amplified Fragment Length Polymorphism (AFLP) and nucleotide sequences of the Translation
Elongation Factor 1α (TEF-1α) and β-tubulin genes. TEF-1α sequences from GenBank, representing previously described species
and clades of the F. solani-Haematonectria haematococca complex, were also included for comparative purposes. Phylogenetic analyses of the TEF-1α data separated the isolates into
three groups corresponding with the three previously described clades (Clades 1–3) for this fungus. The Ethiopian isolates
aggregated into one group corresponding to Clade 3. TEF-1α, β-tubulin and AFLPs further separated the Ethiopian isolates into
a number of clusters and apparently novel phylogenetic lineages. Although the biological and ecological significance of these
lineages and clusters is unclear, our data show that the Ethiopian agricultural environment is rich in species and lineages
of the F. solani-H. haematococca complex. 相似文献
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Random insertional mutagenesis using a marker DNA fragment is an effective method for identifying fungal genes relevant to morphogenesis, metabolism, and so on. Agrobacterium tumefaciens-mediated transformation (AtMT) has long been used as a tool for the genetic modification of a wide range of plant species. Recent study has indicated that A. tumefaciens could transfer T-DNA not only to plant cells but also to fungal cells. In this study, AtMT was applied to Colletotrichum lagenarium for random insertional mutagenesis. We constructed a binary vector pBIG2RHPH2 carrying a hygromycin-resistant gene cassette between the right and left borders of T-DNA. Optimal co-cultivation of C. lagenarium wild-type 104-T with pBIG2RHPH2-introduced A. tumefaciens C58C1 led to the production of 150–300 hygromycin-resistant transformants per 106 conidia. Southern blot analysis revealed that T-DNA was mainly integrated at a single site in the genome and at different sites in transformants. The T-DNA inserts showed small truncations of either end, but the hygromycin-resistant gene cassette inside the T-DNA was generally intact. The mode of T-DNA insertion described above resulted in highly efficient gene recovery from the transformants by thermal asymmetrical interlaced-polymerase chain reaction. The fungal genomic DNA segments flanking T-DNA were identified from five of eight mutants that had defective melanin biosynthesis. The sequence from one of the segments was identical to that of the melanin biosynthesis gene PKS1 of C. lagenarium, which we previously characterized. These results strongly support our notion that AtMT is a possible tool for tagging genes relevant to pathogenicity in the plant pathogenic fungus C. lagenarium. 相似文献
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S. B. F. Galvino‐Costa A. dos Reis Figueira V. V. Camargos P. S. Geraldino X‐J. Hu O. V. Nikolaeva C. Kerlan A. V. Karasev 《Plant pathology》2012,61(2):388-398
Two Potato virus Y (PVY) isolates collected in Brazil, PVY‐AGA and PVY‐MON, were identified as recombinants between two parent genomes, PVYNTN and PVY‐NE‐11, with a novel type of genomic pattern. The new recombinants had an ordinary PVYNTN genome structure for approximately 6·7‐kb from the 5′‐end of the genome whereas the 3′‐terminal 3·0‐kb segment had two fragments of NE‐11‐like sequence separated by another small PVYNTN‐like fragment. PVY strains are defined based on the hypersensitive resistance (HR) response in potato indicators. Both PVY‐AGA and PVY‐MON isolates did not induce the HR in potato cultivars carrying Ny, Nc, or (putative) Nz genes and thus were able to overcome all known resistance genes to PVY. Only one of the two isolates, PVY‐AGA, induced a vein necrosis reaction in tobacco. The biological responses of the potato indicators and tobacco defined PVY‐MON as an isolate of the PVYE strain. To distinguish PVY‐AGA and PVY‐MON from other PVYNTN isolates, an RT‐PCR test was developed utilizing new specific primers from the capsid protein gene area and producing a characteristic 955‐bp band. Serological profiling of these PVY isolates with three monoclonal antibodies revealed an unusual reactivity, where one of the two commercial PVYN‐specific monoclonal antibodies did not recognize PVY‐AGA. The ability of these new PVY recombinants to overcome resistance genes in potato producing mild or no symptoms, combined with the lack of serological reactivity towards at least one PVYN‐specific antibody may present a significant threat posed by these isolates to seed potato production areas. 相似文献
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Gwenaelle Comont Marie-France Corio-Costet Philippe Larignon François Delmotte 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(4):451-464
Phaeomoniella chlamydospora, (Chaetothyriales, Herpotrichiellaceae) is one of the main causal agents of Petri disease and esca on grapevines. We have
used AFLP markers to study the population genetic structure of 74 isolates collected at different spatial scales: 56 isolates
originated from vines with esca disease sampled from four French vineyards (Poitou-Charentes, Aquitaine, Languedoc-Roussillon,
Alsace); 18 isolates were collected from a single plot (Aquitaine vineyard). Significant linkage disequilibrium indicated
that P. chlamydospora populations are not panmictic, whereas the level of haplotypic diversity observed, 72 single multilocus haplotypes identified
in total among the 74 isolates analysed, suggest that reproduction in this species may not be strictly clonal. Clustering
analyses suggests the presence of two genetically differentiated but sympatric clusters of isolates. The level of differentiation
between the two clusters is high (F
ST = 0.23) and significant at 13 out of the 21 loci analyzed. The most plausible explanation for this pattern of admixture is
the coexistence in P. chlamydospora French populations of two predominant clonal lineages. Finally, the low level of spatial genetic differentiation in this
study is consistent with the spread of this fungus through the transport of infected plant material by human activities. 相似文献
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A botanical natural product,AkseBio2, was evaluated under laboratory conditions for its oviposition deterrent, ovicidal and larvicidal (nymphicidal) effects against
the pear psyllaCacopsylla pyri (L.) (Hemiptera: Psyllidae). The product exhibited a strong oviposition deterrent effect for winterform and summerform females
and caused a reduction in the total number of eggs laid in both choice and no-choice assays. Significant mortalities in freshly
laid eggs (0–48 h) and various nymphal stages of the pest were recorded in toxicity assays. At a concentration of 0.1% (formulation),
the highest biological activity of the product was recorded against the young (1st and 2nd) nymphal stages (up to 87.4% mortality)
in comparison with the other biological stages of the pest. It was less active against the older (3rd-5th) nymphs, causing
62.1% mortality at the same concentration. In assays with non-target organisms, a significant negative effect was not observed.
There were no significant changes on treated plants up to 7 days after treatment in any trial, nor was there any phytotoxicity
on plant tissue as a result ofAkseBio2 treatments. The results suggest that the product can be used in psylla control instead of synthetic insecticides and may
serve as an integrated pest management (IPM) component in pear orchards.
http://www.phytoparasitica.org posting July 14, 2004. 相似文献
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抗坏血酸过氧化物酶（Ascorbate peroxidase, APX）是植物活性氧代谢中重要的抗氧化酶之一,在植物抵抗氧化胁迫方面发挥重要作用。利用生物信息学方法对芹菜基因组中的APX基因家族成员进行鉴定和分析,并通过实时荧光定量PCR（quantitative real\|time PCR, qRT-PCR）验证分析AgAPXs在高温胁迫下的表达情况,为开展芹菜APX基因参与高温胁迫调控机制提供依据。结果表明：芹菜基因组中共有9个APX基因,随机分布在5个染色体上,并出现了基因片段复制现象;大多数基因被定位在细胞质中。系统发育分析表明,AgAPX基因家族可分为3个亚族,同一亚族中的成员具有相似的基因结构和基序。启动子顺式元件分析表明,大多数AgAPX基因含有多种与生长发育、植物激素和逆境胁迫相关的顺式元件。高温胁迫下,芹菜APX活性提高。qRT-PCR分析表明,AgAPXs在不同时间的高温处理下表达具有显著差异,并与转录组表达丰度相一致,AgAPX2、AgAPX3、AgAPX4、AgAPX5、AgAPX7的表达量和APX活性具有显著相关性,推测AgAPXs可能参与了芹菜抵御高温的调控过程。本研究初步鉴定并提供了芹菜APX基因家族成员信息,为今后进一步探索芹菜APX基因功能提供了重要的研究基础。 相似文献
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Mariella Matilde Finetti-Sialer Tiziana Mascia Fabrizio Cillo Crisostomo Vovlas Donato Gallitelli 《European journal of plant pathology / European Foundation for Plant Pathology》2012,132(3):317-322
The biological and molecular characterization is reported of a Watermelon mosaic virus isolate, denoted WMV-Le, associated with a necrotic phenotype of watermelon plants grown in the Provinces of Lecce and Taranto
(Apulia, southern Italy). The fully sequenced WMV-Le genome consists of 10,045 nucleotides and is 99.1% similar to that of
WMV-C05-270, a French isolate from melon of the WMV molecular group 3. Using recombination detection program RDP3, putative
recombination breakpoints were identified close to nucleotide positions 42 to 1892, covering the 5′UTR/P1/HC-Pro region. The
event represents the insertion of a sequence fragment of an isolate similar to WMV-FBR04-37 in the background of an isolate
similar to WMV-FMF00-LL1. The field symptomatology was reproduced in watermelon plants grown in an experimental greenhouse
but the virus induced severe symptoms also in Cucumis sativus, C. melo, Cucurbita maxima and C. pepo . 相似文献
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Richard Michelmore Joan Wong 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(1):19-30
Lettuce downy mildew caused by Bremia lactucae has long been a model for understanding biotrophic oomycete–plant interactions. Initial research involved physiological and
cytological studies that have been reviewed earlier. This review provides an overview of the genetic and molecular analyses
that have occurred in the past 25 years as well as perspectives on future directions. The interaction between B. lactucae and lettuce (Lactuca sativa) is determined by an extensively characterized gene-for-gene relationship. Resistance genes have been cloned from L. sativa that encode proteins similar to resistance proteins isolated from other plant species. Avirulence genes have yet to be cloned
from B. lactucae, although candidate sequences have been identified on the basis of motifs present in secreted avirulence proteins characterized
from other oomycetes. Bremia lactucae has a minimum of 7 or 8 chromosome pairs ranging in size from 3 to at least 8 Mb and a set of linear polymorphic molecules
that range in size between 0.3 and 1.6 Mb and are inherited in a non-Mendelian manner. Several methods indicated the genome
size of B. lactucae to be ca. 50 Mb, although this is probably an underestimate, comprising approximately equal fractions of highly repeated
sequences, intermediate repeats, and low-copy sequences. The genome of B. lactucae still awaits sequencing. To date, several EST libraries have been sequenced to provide an incomplete view of the gene space.
Bremia lactucae has yet to be transformed, but regulatory sequences from it form components of transformation vectors used for other oomycetes.
Molecular technology has now advanced to the point where rapid progress is likely in determining the molecular basis of specificity,
mating type, and fungicide insensitivity. 相似文献
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为有效防治由不同类型卵菌引起的植物病害,该研究对数据库中的霜霉、疫霉和腐霉3类不同卵菌的全基因组数据进行序列特征分析、同源性分析和共线性分析以及同源差异基因富集通路分析。结果显示,霜霉、疫霉和腐霉来自独立的谱系,且疫霉与霜霉的亲缘关系较近;疫霉的致病相关基因数量最多,主要有RxLR、CRN、NPP、NF和PcF基因家族,霜霉的致病相关基因数量次之,腐霉的致病相关基因数量最少;3类卵菌共确定了13 392个同源基因,其中3类卵菌均共有的同源基因为3 786个,不同菌种的同源基因数量差异较大,整体表现为疫霉>霜霉>腐霉;同源差异基因富集程度最高的前20个通路主要是基础代谢的通路和中间代谢通路,其中抗坏血酸和藻酸盐代谢、ABC转运蛋白和果糖和甘露糖代谢相对富集程度较高,基因数目也较多。 相似文献
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Ivan Lozano Francisco Morales 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(4):673-680
The complete nucleotide sequences of RNAs 1 and 2 of Rice stripe necrosis virus (RSNV) were determined and compared to the corresponding genomes of all sequenced, rod-shaped plant viruses. The genome organisation
of RSNV RNA1 and RNA2 is nearly identical to that of Beet necrotic yellow vein virus (BNYVV) and Beet soil-borne mosaic virus (BSBMV), definitive species of the genus Benyvirus. As demonstrated for BNYVV and BSBMV, the RNA1 of RSNV also encodes a single ORF with putative replicase-associated motifs,
which distinguishes benyviruses from all other viruses possessing rod-shaped particles. As described for BNYVV, RNSV RNA-2
also contains six ORFs: the capsid protein gene, the read-through protein gene, a triple gene block gene that codes for three
different proteins, and a 17 kDa cysteine-rich protein. RNAs 3 and 4 (or 5 in the case of BNYVV), identified in natural infections
of BNYVV and BSBMV, were not detected in any of the 44 RSNV cDNA clones obtained in this investigation. Nevertheless, phylogenetic
and amino comparative acid sequence analyses demonstrated that RSNV is more closely related to BNYVV and BSBMV than to any
other rod-shaped plant virus characterised to date. 相似文献