共查询到20条相似文献，搜索用时 15 毫秒
1.
ABSTRACT Strains of Ralstonia solanacearum have been shown to cause bacterial wilt in some, but not all, ecotypes of Arabidopsis thaliana. We demonstrate here that after inoculation of the leaves of resistant ecotype S96 with R. solanacearum strain Ps95 necrosis around the inoculation site rapidly appeared and no further symptoms developed in the plant. Leaves of susceptible ecotype N913 completely wilted 7 days after inoculation with Ps95, and symptoms spread systemically throughout the whole plant within 2 weeks after inoculation. These results suggest that the resistance of Arabidopsis S96 to R. solanacearum is due to a response similar to the hypersensitive response (HR) observed in other plant diseases. Northern blot analysis of the expression of defense-related genes, known to be differentially induced during the HR in Arabidopsis, indicated that pathogenesis-related protein PR-1, glutathione S-transferase (GST1), and Cu, Zn superoxide dismutase (SOD) mRNAs increased significantly in S96 leaves between 3 to 12 h after infiltration with Ps95. The induction of these genes in susceptible ecotype N913 by Ps95 was clearly delayed. Genetic analysis of crosses between resistant ecotype S96 and susceptible ecotype N913 indicated that resistance to Ps95 is due to a single dominant locus. 相似文献
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ABSTRACT One susceptible and two resistant cultivars of tomato were tested for differences in infection by Ralstonia solanacearum and for the subsequent multiplication, colonization, and production of the wilt-inducing virulence factor, exopolysaccharide I (EPS I). Bacterial ingress into the taproot was fastest in the susceptible cv. Marion, followed by the resistant cvs. L285 (fivefold slower) and Hawaii 7996 (15-fold slower). Once inside the taproot, R. solanacearum colonized, to some extent, almost all regions of the resistant and susceptible plants. However, colonization occurred sooner in the susceptible than in the resistant cultivars, as measured by viablecell counts of bacteria in the midstems. Rates of multiplication and maximum bacterial cell densities were also greater in the susceptible than in the resistant cultivars. Growth experiments utilizing xylem fluid from infected and uninfected plants indicated that neither antimicrobial activities nor reduced levels of growth-supporting nutrients in the xylem fluids were responsible for the reduced bacterial multiplication in the resistant cultivars. Quantification of EPS I in the infected plants, using an enzyme-linked immunosorbent assay, revealed that the bacterial populations in the susceptible cultivar produced greater amounts of EPS I per plant than those in the resistant cultivars. Immunofluorescence microscopy using antibodies against either EPS I or R. solanacearum cells revealed that bacteria and EPS I were distributed throughout the vascular bundles and intercellular spaces of the pith in the susceptible cultivar, whereas in the resistant cultivars, bacteria and EPS I were restricted to the vascular tissues. 相似文献
4.
Feng DX Deslandes L Keller H Revers F Favery B Lecomte P Hirsch J Olivier J Marco Y 《Phytopathology》2004,94(3):289-295
ABSTRACT To characterize host genes required for a compatible interaction, we identified a novel recessive Arabidopsis thaliana mutant, nws1 (no wilt symptoms), that failed to develop wilt symptoms in response to virulent strains of the phytopathogenic bacterium, Ralstonia solanacearum. The absence of wilting in nws1 plants was not correlated with a cell death phenotype or a constitutive expression of salicylic acid-, jasmonic acid- or ethylene-associated genes. In addition, this mutation, which conferred a symptomless phenotype in response to all the R. solanacearum strains tested, was highly specific to this pathogen, because nws1 responses to other plant pathogens, including oomycetes, nematodes, viruses, and other bacteria, were identical to those of wild-type Col-5 plants. Finally, the lack of disease development was shown to be different than RRS1-R-mediated resistance. The identification of mutants such as nws1, that are unable to develop disease, should lead to the isolation of target host factors required for pathogen growth or fitness, or of factors modified by the invading microorganism to avoid or inactivate plant defense mechanisms, and should bring a better understanding of bacterial wilt diseases. 相似文献
5.
Distribution of Pseudomonas solanacearum in the stem tissues of tomato plants with different levels of resistance to bacterial wilt 总被引：3，自引：0，他引：3
Ten tomato cultivars, from the USA, Taiwan and French Antilles, were compared for resistance to bacterial wilt as measured by disease and pathogen population invasiveness and density in the stem at the collar and midstem regions. On the basis of disease incidence, cultivars ranked from highly susceptible to totally resistant. By contrast, no significant difference was observed in bacterial population in wilting plants, regardless of the cultivar. All symptomless plants were latently infected at the collar level. Percentage of symptomless plants with bacteria at the midstem level was significantly correlated with the degree of resistance; the more resistant, the lower the stem colonization. Restriction of Pseudomonas solanacearum invasiveness in the vascular tissues of the stem is associated with resistance properties in tomato. This observation may be useful in developing improved criteria for selecting stable resistance to the disease. 相似文献
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Ethylene-insensitive tobacco shows differentially altered susceptibility to different pathogens 总被引：1，自引：0，他引：1
ABSTRACT Transgenic tobacco plants (Tetr) expressing the mutant etr1-1 gene from Arabidopsis thaliana are insensitive to ethylene and develop symptoms of wilting and stem rot when grown in nonautoclaved soil. Several isolates of Fusarium, Thielaviopsis, and Pythium were recovered from stems of diseased Tetr plants. Inoculation with each of these isolates of 6-week-old plants growing in autoclaved soil caused disease in Tetr plants but not in nontransformed plants. Also, when 2-week-old seedlings were used, nontransformed tobacco appeared nonsusceptible to the Fusarium isolates, whereas Tetr seedlings did develop disease. Tetr seedlings were not susceptible to several nonhost Fusarium isolates. In contrast to results with Fusarium isolates, inoculation of 2-week-old seedlings with a Thielaviopsis isolate resulted in equal symptom development of nontransformed and Tetr tobacco. In order to explore the potential range of pathogens to which Tetr tobacco plants display enhanced susceptibility, the pathogenicity of several root and leaf pathogens was tested. Tetr plants were more susceptible to the necrotrophic fungi Botrytis cinerea and Cercospora nicotianae and the bacterium Erwinia carotovora, but only marginally more to the bacterium Ralstonia solanacearum. In contrast, the biotrophic fungus Oidium neolycopersici, the oomycete Peronospora tabacina, and Tobacco mosaic virus caused similar or less severe symptoms on Tetr plants than on nontransformed plants. Total peroxidase activity of Tetr plants was lower than that of nontransformed plants, suggesting a role for peroxidases in resistance against necrotrophic microorganisms. A comparable range of pathogens was examined on Arabidopsis and its ethylene-insensitive mutants etr1-1 and ein2-1. With the exception of one Fusarium isolate, ethylene insensitivity increased susceptibility of Arabidopsis plants to a similar spectrum of necrotizing pathogens as in tobacco. Thus, both ethylene-insensitive tobacco and Arabidopsis plants appear to be impaired in their resistance to necrotrophic pathogens. 相似文献
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ABSTRACT Arabidopsis thaliana ecotypes vary in their responses to viruses. In this study, we analyzed the variation in response of A. thaliana ecotype Tsu-0 to Cauliflower mosaic virus (CaMV). This ecotype was previously reported to be resistant to two CaMV isolates (CM1841 and CM4-184), but susceptible to W260. In this study, we show that Tsu-0 is resistant to four additional CaMV isolates. CaMV propagated within the rosette leaves of Tsu-0 plants, but did not appear to spread systemically into the inflorescence. However, virus viability in rosette leaves of Tsu-0 plants apparently was not compromised because infectious CaMV could be recovered from these organs. W260 overcomes Tsu-0 resistance by a passive mechanism (i.e., this virus avoids activating plant defenses). The portion of the viral genome responsible for W260 resistance breakage was mapped to the 5' third of gene VI, which we have termed RBR-1. This region is also responsible for controlling the ability of CaMV to infect different types of solanaceous plants. Hence, the pathways by which plants of different families interact with CaMV may be conserved through evolution. 相似文献
8.
Huang HE Liu CA Lee MJ Kuo CG Chen HM Ger MJ Tsai YC Chen YR Lin MK Feng TY 《Phytopathology》2007,97(8):900-906
ABSTRACT Expression of a foreign gene to enhance plant disease resistance to bacterial pathogens is a favorable strategy. It has been demonstrated that expressing sweet pepper ferredoxin-I protein (PFLP) in transgenic plants can enhance disease resistance to bacterial pathogens that infect leaf tissue. In this study, PFLP was applied to protect tomato (Lycopersicon esculentum cv. cherry Cln1558a) from the root-infecting pathogen, Ralstonia solanacearum. Independent R. solanacearum resistant T(1) lines were selected and bred to produce homozygous T(2) generations. Selected T(2) transgenic lines 24-18-7 and 26-2-1a, which showed high expression levels of PFLP in root tissue, were resistant to disease caused by R. solanacearum. In contrast, the transgenic line 23-17-1b and nontransgenic tomato, which showed low expression levels of PFLP in root tissue, were not resistant to R. solanacearum infection. The expansion of R. solanacearum populations in stem tissue of transgenic tomato line 24-18-7 was limited compared with the nontransgenic tomato Cln1558a. Using a detached leaf assay, transgenic line 24-18-7 was also resistant to maceration caused by E. carotovora subsp. carotovora; however, resistance to E. carotovora subsp. carotovora was less apparent in transgenic lines 26-2-1a and 23-17-1b. These results demonstrate that PFLP is able to enhance disease resistance at different levels to bacterial pathogens in individual tissue of transgenic tomato. 相似文献
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青枯雷尔氏菌无致病力突变菌株的构建及其防效评价模型分析 总被引：2，自引：0，他引：2
利用青枯雷尔氏菌(Ralstonia solanacearum)无致病力菌株防治番茄青枯病具有很好的应用潜力。作者通过分离筛选自然弱毒株、60Co辐射诱变和EZ-Tn5插入诱变,分别获得3、12和40株青枯雷尔氏菌无致病力突变菌株。经盆栽番茄苗致病性检测,15 d后均未发病,证实均为无致病力青枯雷尔氏菌。进一步对番茄青枯病的防治试验表明,从番茄青枯病发病田块分离的无致病力突变菌株FJAT1458的防治效果最好,防效达100%。该菌株能定殖番茄植株根系土壤、根部和茎部,定殖数量均表现为“先增后减”的趋势,并且接种浓度越大、苗龄越小,定殖数量越大。从构建的防效模型可以看出,不同接种浓度条件下,植株发病率随时间变化符合的回归方程不同,相关系数R值也不同,接种浓度越大,R值越小。本研究获得的青枯雷尔氏菌无致病力突变菌株FJAT1458对番茄青枯病具有很好的防病效果。 相似文献
10.
Role of Extracellular Polysaccharide and Endoglucanase in Root Invasion and Colonization of Tomato Plants by Ralstonia solanacearum 总被引：1，自引：0，他引：1
ABSTRACT Ralstonia solanacearum is a soilborne plant pathogen that normally invades hosts through their roots and then systemically colonizes aerial tissues. Previous research using wounded stem infection found that the major factor in causing wilt symptoms was the high-molecular-mass acidic extracellular polysaccharide (EPS I), but the beta-1,4-endoglucanase (EG) also contributes to virulence. We investigated the importance of EPS I and EG for invasion and colonization of tomato by infesting soil of 4-week-old potted plants with either a wild-type derivative or genetically well-defined mutants lacking EPS I, EG, or EPS I and EG. Bacteria of all strains were recovered from surface-disinfested roots and hypocotyls as soon as 4 h after inoculation; that bacteria were present internally was confirmed using immunofluorescence microscopy. However, the EPS-minus mutants did not colonize stems as rapidly as the wild type and the EG-minus mutant. Inoculations of wounded petioles also showed that, even though the mutants multiplied as well as the wild type in planta, EPS-minus strains did not spread as well throughout the plant stem. We conclude that poor colonization of stems by EPS-minus strains after petiole inoculation or soil infestation is due to reduced bacterial movement within plant stem tissues. 相似文献
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Bacterial wilt resistance in tomato associated with tolerance of vascular tissues to Pseudomonas solanacearum 总被引：2，自引：0，他引：2
High populations of Pseudomonas solanacearum were detected in some, but not all stems of bacterial wilt resistant ('CRA 66', 'Hawaii 7996' and 'Caraibo') and susceptible ('Floradel') tomatoes. Latent infection, i.e. spread of P. solanacearum into xylem vessels, was confirmed in Caraibo, Hawaii 7996 and 'CRA 66' (the resistant parent of Caraibo). None of the plants within the resistant cultivars wilted and those cultivars were characterized by tolerance of the vascular tissues to high bacterial densities. In contrast, plants of cultivar Floradel showed consistent symptoms and wilted rapidly, with higher mean bacterial density than resistant cultivars. Bacterial wilt resistance was not associated with resistance to bacterial root invasion but with the capability of the plant to limit P. solanacearum colonization in the stem. The extent of bacterial colonization is proposed as a criterion to quantify tolerance, complementary to absence of external wilt symptoms used in breeding programmes for resistance. 相似文献
12.
Activities of polygalacturonase, pectin lyase, and cellulase increased in susceptible, catechol-treated, and resistant tomato plants, after inoculation withFusarium oxysporum f.lycopersici (Sacc.) Snyder and Hansen race 2. The catechol-treated and the resistant plants remained symptomless, while susceptible plants developed symptoms of disease. It is therefore suggested that increased activity of cell-wall-degrading enzymes in inoculated plants does not necessarily cause the development of disease symptoms. 相似文献
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ABSTRACT Southern wilt of geraniums (Pelargonium hortorum), caused by the soilborne bacterium Ralstonia solanacearum race 3 biovar 2 (R3bv2), has inflicted significant economic losses when geranium cuttings latently infected with this quarantine pest were imported into the United States. Little is known about the interaction between R. solanacearum and this ornamental host. Using UW551, a virulent R3bv2 geranium isolate from a Kenyan geranium, we characterized development of Southern wilt disease and R3bv2 latent infection on geranium plants. Following soil inoculation, between 12 and 26% of plants became latently infected, carrying average bacterial populations of 4.8 x 10(8) CFU/g of crown tissue in the absence of visible symptoms. Such latently infected plants shed an average of 1.3 x 105 CFU/ml in soil run-off water, suggesting a non-destructive means of testing pools of asymptomatic plants. Similarly, symptomatic plants shed 2 x 10(6) CFU/ml of run-off water. A few hundred R. solanacearum cells introduced directly into geranium stems resulted in death of almost all inoculated plants. However, no disease transmission was detected after contact between wounded leaves. Increasing temperatures to 28 degrees C for 2 weeks did not convert all latently infected plants to active disease, although disease development was temperature dependent. Holding plants at 4 degrees C for 48 h, a routine practice during geranium cutting shipment, did not increase frequency of latent infections. R. solanacearum cells were distributed unevenly in the stems and leaves of both symptomatic and latently infected plants, meaning that random leaf sampling is an unreliable testing method. UW551 also caused potato brown rot and bacterial wilt of tomato, surpassing race 1 strain K60 in virulence on tomato at the relatively cool temperature of 24 degrees C. 相似文献
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青枯菌(Pseudomonas solanacearum)在番茄抗、感病品种根部的吸附、侵入和繁殖 总被引：7，自引：0，他引：7
采用不同的方法接种和利用扫描、透射电镜观察,研究不同致病力的青枯菌对番茄抗病及感病品种根部的吸附、侵入与繁殖。发现番茄抗病品种与感病品种的植株体内在菌体数量上有明显差异,而与青枯菌对番茄根部的吸附关系不显著。电镜观察发现青枯菌强致病力菌株菌体能以游离的形式存在于番茄感病品种根部的细胞间隙中,并能降解植株细胞壁、破坏原生质膜;青枯菌强致病力菌株菌体在抗病品种根内和青枯菌强致病力菌株在抗病及感病品种根内均被番茄植株细胞壁吸附,并且被细胞壁周围的浓密物质所包围。 相似文献
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番茄青枯病内生拮抗细菌的筛选 总被引：46，自引：2，他引：46
从广西一些市县采集番茄茎标本分离得到55个细菌菌株,分属为芽孢杆菌(Bacillus spp.)、黄单胞菌(Xanthomonas spp.)、假单胞菌(Pseudomonas spp.)和欧文氏菌(Erwinia spp.),其中芽孢杆菌为优势种群。经回接测试,有36个菌株为番茄植株内生菌。这些内生菌只有7个菌株对番茄青枯病菌有拮抗作用,芽孢杆菌B47菌株对番茄青枯病菌拮抗作用较强,经室内和田间初步防治测定,它对番茄青枯病有较好的防治效果。 相似文献
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Akira Masunaka Kazuhiro Nakaho Masao Sakai Hideki Takahashi Shigehito Takenaka 《Journal of General Plant Pathology》2009,75(4):281-287
The biocontrol agent Pythium oligandrum (PO) can suppress bacterial wilt caused by Ralstonia solanacearum (RS) in tomato. To understand the primary biocontrol mechanisms of bacterial wilt by PO, we pretreated tomato plants with
sterile distilled water or preinoculated them with PO, followed by inoculation with RS, then observed PO and RS in fixed sections
of tomato tissues using a confocal laser-scanning microscope and fluorescence labeling until 14 days after the inoculation
with RS. Horizontal and vertical movement of RS bacteria was frequently observed in the xylem vessels of roots and stems of
tomato plants (cv. Micro-Tom) that had not been inoculated with PO. In plants that were preinoculated with PO, the movement
of RS was suppressed, and bacteria appeared to be restricted to the pit of vessels, a reaction similar to that observed in
resistant rootstocks. PO colonization was mainly observed at the surfaces of taproots, the junctions between taproots and
lateral roots, and the middle sections of the lateral roots. PO was not observed near wound sites or root tips where RS tended
to colonize. However, RS colonization was significantly repressed at these sites in PO preinoculated plants. These observations
suggest that the induction of plant defense reactions is the main mechanism for the control of tomato bacterial wilt by PO,
not direct competition for infection sites. 相似文献
18.
TMV侵染不同抗性番茄品种之后引起的过氧化物酶活性及同工酶的变化 总被引：6，自引：0，他引：6
本文论述了不同抗性番茄品种在接种了TMV之后体内过氧化物酶及其同工酶的变化趋势。不同品种番茄幼苗接种TMV之后30天内病毒含量、过氧化物酶活性及其同工酶的测定结果表明:所有接种的番茄幼苗与健株对照相比均表现酶活性的增强及酶带数目的增多;但不同抗性品种,酶活性交化曲线及同工酶谱带的变化趋势有所不同:感性品种北京早红(+/+)及耐病品种强力米寿接种TMV之后,病毒含量迅速上升,在第15天达到最高峰,同时植株开始显症,其酶活性曲线呈现出1个增值高峰,即酶活性只在显症之后迅速上升于第24天达到最高峰,病株在症状发展过程中产生2条健株所没有的具高迁移率的同工酶谱带A与B。抗性品种Tm-2(Tm-2/+)抑制TMV在体内的增殖,在接种之后30天内植株不表现典型外部症状,其酶活性曲线具有2个增酶高峰,即在接种后第12天达到最高峰,并在第21天有1个新的高峰;在酶活性高峰期,接种植株也产生同工酶谱A与B,与感性品种不同的是谱带A与B形成较早,同时,抗性品种还产生感病品种所没有的1条同工酶谱带F。上述过氧化物酶活性及同工酶的变化趋势可以成为鉴定品种抗性一个有价值的生化指标。 相似文献
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青枯病植物疫苗对番茄根系土壤微生物群落结构的影响 总被引：2，自引：0，他引：2
为了探讨青枯雷尔氏菌无致病力菌株FJAT-1458作为青枯病植物疫苗菌株对番茄根系土壤微生物群接种处理后番茄根系土壤微生物PLFAs组成、含量、微生物群落结构及多样性的变化。结果表明,与清水对照相比,接种菌株FJAT-1458后,番茄根系土壤微生物脂肪酸组成及含量发生了明显变化,可分为减少型、无变化型和增加型。进一步分析表明,菌株FJAT-1458能促进番茄根系土壤微生物总量、细菌总量和真菌总量的增加,增加幅度分别为5.98%~47.36%、2.07%~58.07%和5.65%~74.42%,对放线菌生长起到先抑制后促进作用。此外,接种菌株FJAT-1458后番茄根系土壤微生物群落的Shannon-wiener指数显著增加,21 d增加量最高(13.32%)。聚类分析表明,菌株FJAT-1458处理组与对照组的番茄根系土壤微生物均划分为3个群落类型(兰氏距离分别为3.28和4.62),但它们各自群落组成及特征不同;同时主成分分析也将2种处理划分在2个不同类群中。上述结果说明菌株FJAT-1458处理能明显改变番茄根系土壤微生物群落结构,增加其多样性,从而提高土壤微生态系统的稳定性,增强土壤抑制病害能力。 相似文献
20.
无致病力青枯菌株对番茄青枯病的防治效果 总被引：14，自引：0，他引：14
用紫外诱变法获得的青枯无致病力菌株ATm0 4 4和Asp0 6 1对致病菌没有直接的抑制作用 ;处理番茄后对青枯病产生抗性 ;两菌株可在番茄体内定殖并繁殖 ,移栽浸根是最佳的处理方法。盆栽试验结果表明 ,番茄经ATm0 4 4和Asp0 6 1处理后 ,分别较对照推迟 9和 7d发病 ,2 0d后的防效达 56 .7%和 53.4 %。田间小区试验结果表明 ,经ATm0 4 4和Asp0 6 1菌悬液浸根处理番茄 ,1 5d后对青枯病的防治效果分别为 53.8%和 37.7%。 相似文献