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1.
Shintaro Tsujimoto Kazuhiro Nakaho Masanori Adachi Kouhei Ohnishi Akinori Kiba Yasufumi Hikichi 《Journal of General Plant Pathology》2008,74(1):71-75
Ralstonia solanacearum strain OE1-1 (OE1-1) systemically invades tobacco plants and causes bacterial wilt. A type II secretion system (T2SS)-deficient
mutant of OE1-1, derived from EZ::TN<KAN-2>transposon-insertion, retained the ability of the parent strain to produce exopolysaccharide
in vitro and grow in intercellular spaces immediately after invasion of host plants, but lost the ability to systemically
infect the host. With transmission electron microscopy, the mutant was not observed in xylem vessels. These findings suggest
that the T2SS contributes to systemic infection by enabling the bacteria to invade xylem vessels. 相似文献
2.
Taro Mori Katsumi Ozaki Hiromi Matsusaki Naotaka Matsuzoe 《Journal of General Plant Pathology》2007,73(2):142-146
To study the behavior and mutation of Ralstonia solanacearum in Solanum toxicarium, which is resistant to bacterial wilt, S. toxicarium was grown in aseptic culture and inoculated with R. solanacearum. Although 60%–80% of the inoculated plants were wilting after 2 to 3 days, most wilted plants had recovered by 20 days after
inoculation. The pathogen was reisolated from over 98% of inoculated plant stems, but the percentage of recovery decreased
the closer the isolation sites were toward the upper stem sections. Three colony types, characterized as fluidal white, nonfluidal
red, and a mixture of fluidal white and nonfluidal red, were reisolated from the stems. Nonfluidal red colonies were less
virulent on tomato plants than fluidal white colonies. 相似文献
3.
The root-associated fungus LtVB3 was formerly reported as a potential, new biocontrol agent of Verticillium yellows of Chinese
cabbage and Fusarium wilt of tomato. According to molecular phylogenetic analysis of the ITS 1-5.8S rDNA-ITS 2 gene regions
and morphological characteristics, LtVB3 is here identified as Meliniomyces
variabilis, a recently described species [formerly called “Variable White Taxon” (VWT)] in a new genus erected to accommodate sterile
fungi with phylogenetic affinities to Rhizoscyphus
ericae, an ericoid mycorrhizal fungus. In vitro inoculation experiments showed that LtVB3 colonized the roots of torch azalea and
eucalyptus; however, growth was enhanced only in azalea but not in eucalyptus. Hyphae of M.
variabilis formed intracellular structures typical of ericoid mycorrhizas in epidermal cells of azalea roots but did not produce any
typical ectomycorrhizal structures with or within root cells of either host. In LtVB3-treated eucalyptus roots, some cells
in the epidermal and cortical layers had wall appositions and thickenings, which appeared to restrict fungal growth. 相似文献
4.
Yongxiang Zhang Ewen M. Callaway Jeffrey B. Jones Mark Wilson 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(3):379-390
The plasmid pUFZ75 conferred constitutive GFP expression on the bacterial pathogen Xanthomonas euvesicatoria (syn. X. campestris pv. vesicatoria). Colonisation of the tomato phyllosphere and invasion of tomato leaves by X. euvesicatoria was examined using both fluorescence and confocal laser scanning microscopy. Xanthomonas euvesicatoria established a limited population on the tomato leaf surface, primarily occupying the depressions between epidermal cells
and around the stomata, prior to invasion of the leaf via the stomata and subsequent growth within the substomatal chamber
and the leaf apoplast. Additionally, hrp-gfp fusions were used to report on the temporal and spatial expression of hrp genes during epiphytic colonisation and invasion. Xanthomonas euvesicatoria cells carrying hrpG- and hrpX-gfp reporter constructs were not fluorescent in vitro on non-hrp-inducing LB agar but did exhibit a low level of fluorescence on the leaf surface within 24 h of inoculation, particularly
in the vicinity of stomata. Cells carrying hrpG- and hrpX-gfp fusions exhibited high levels of fluorescence 72 h after inoculation in the substomatal chamber and the leaf apoplast. Cells
carrying the hrpF-gfp fusion were slightly fluorescent on LB agar and showed no further increase in fluorescence on the leaf surface by 24 h after
inoculation, but did show a significant increase in fluorescence 72 h after inoculation in the substomatal chamber and apoplast.
The apparent low-level induction of the regulators hrpG and hrpX on the tomato leaf surface may suggest that some of the genes of the X. euvesicatoria HrpG/HrpX regulon are up- or down-regulated prior to invasion of the stomata while still on the leaf surface. 相似文献
5.
Sakhr Ajouz Marc Bardin Philippe C. Nicot Mohamed El Maâtaoui 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(1):31-42
Botrytis cinerea is able to build-up resistance to pyrrolnitrin, an antibiotic produced by diverse biocontrol agents, possibly compromising
the durability of this method of disease control. The development of two near-isogenic lines of B. cinerea differing in their level of resistance to pyrrolnitrin was compared in tomato plants and on PDA medium. In tomato plants,
significant differences in the percentage of infected petioles 1 day after inoculation and in symptom progression on petioles
and stems were observed between the resistant mutant and the sensitive wild-type parent, suggesting a difference in their
level of aggressiveness. Cytohistological investigations revealed that conidia of both near-isogenic lines germinated 6 h
after inoculation and mycelium developed within petiole tissues 12 h after inoculation. However, while the wild-type parent
isolate spread throughout the petiole and rapidly invaded the stem tissues via the leaf-abscission zone 72 h after inoculation, the pyrrolnitrin-resistant mutant failed to extend beyond petiole tissues
to invade the stem. Moreover, 72 h after inoculation, the mycelial development of the pyrrolnitrin-resistant mutant was accompanied
by abnormal glycogen accumulation and chlamydospore-like cell formation. In contrast, wild-type parent mycelium was normally
structured with intensive colonization of stem tissues. Additionally, on PDA medium the mycelium of the pyrrolnitrin-resistant
mutant was less vigorous than the wild-type isolate. These results suggest that the acquisition of pyrrolnitrin-resistance
in B. cinerea is accompanied by changes in mycelial structure and reduction in mycelial growth, leading to a noticeable loss of aggressiveness
on tomato plants. 相似文献
6.
Nonpathogenic isolates of Fusarium oxysporum can be successful antagonists of pathogenic forms of the same fungal species that commonly attacks crop plants. The characteristics that distinguish nonpathogenic from pathogenic forms are not well understood. In this study, the mode of root colonization of Eucalyptus viminalis seedlings by a nonpathogenic F. oxysporum strain is described at the ultrastructural level. Root systems of E. viminalis plants were inoculated with nonpathogenic F. oxysporum strain Fo47 in an in vitro model system. Changes in the occurrence of nonesterified and methyl-esterified pectins in colonized E. viminalis roots were evaluated by in situ immunolabeling using two monoclonal antibodies, JIM 5 and JIM 7. Modes of penetration and root colonization patterns in E. viminalis seedlings by the nonpathogenic fungus were similar to those described for pathogenic forms of F. oxysporum. However, root interactions differed in that the nonpathogenic fungus did not induce host tissue damage. No papilla-like appositions were observed in host cells in response to invading hyphae, which did not disrupt the host plasma membrane in many cases, suggesting that a biotrophic relationship was established. Root colonization by the nonpathogenic strain did not induce alteration in JIM 7 labeling of methyl-esterified pectin in E. viminalis cell walls, whereas nonesterified pectin was detected to a significantly greater extent in cell walls of roots colonized by the fungus. Pectin components decreased slightly only at points of hyphal contact with host cells. Because nonpathogenic strains utilize pectin in pure culture, host control over enzyme activity or production by the fungi may at least partly explain their compatible interactions with host tissues. 相似文献
7.
Masato?Kawabe Kohei?Mizutani Takanobu?Yoshida Tohru?Teraoka Katsuyoshi?Yoneyama Isamu?Yamaguchi Tsutomu?Arie
We selected a reduced-pathogenicity mutant of Fusarium oxysporum f. sp. lycopersici, a tomato wilt pathogen, from the transformants generated by restriction enzyme-mediated integration (REMI) transformation. The gene tagged with the plasmid in the mutant was predicted to encode a protein of 321 amino acids and was designated FPD1. Homology search showed its partial similarity to a chloride conductance regulatory protein of Xenopus, suggesting that FPD1 is a transmembrane protein. Although the function of FPD1 has not been identified, it does participate in the pathogenicity of F. oxysporum f. sp. lycopersici because FPD1-deficient mutants reproduced the reduced pathogenicity on tomato.The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession number AB110097 相似文献
8.
Ju Ding Kai Shi Yan Hong Zhou Jing Quan Yu 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(1):141-150
Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum (FO), is one of the major diseases in cucumber (Cucumis sativus) production. Root and foliar applications of 24-epibrassinolide (EBL), an immobile phytohormone with antistress activity,
were evaluated for their effects on the incidence of Fusarium wilt and changes in the microbial population and community in
roots of cucumber plants. EBL pre-treatment to either roots or shoots significantly reduced disease severity followed by an
improved plant growth regardless of the treatment methods applied. EBL applications decreased the Fusarium population on root surfaces and in nutrient solution, but increased the population of fungi and actinobacteria on root surfaces. PCR-DGGE analysis showed that FO-inoculation had significant effects on the bacterial community on root
surfaces as expressed by a decreased diversity index and evenness index, but EBL applications alleviated these changes. Moreover,
several kinds of decomposing bacteria and growth-promoting bacteria were identified from root surfaces of FO-inoculated plants
and EBL-pre-treated plants, respectively. Overall, these results show that the microbial community on root surfaces was affected
by a complex interaction between phytohormone-induced resistance and plant pathogens. 相似文献
9.
Dvora Swartzberg Beny Kirshner Dalia Rav-David Yigal Elad David Granot 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(3):289-297
Botrytis cinerea is a non-specific, necrotrophic pathogen that attacks many plant species, including Arabidopsis and tomato. Since senescing leaves are particularly susceptible to infection by B. cinerea, we hypothesized that the fungus might induce senescence as part of its mode of action and that delaying leaf senescence
might reduce the severity of B. cinerea infections. To examine these hypotheses, we followed the expression of Arabidopsis SAG12, a senescence-specific gene, upon infection with B. cinerea. Expression of SAG12 is induced by B. cinerea infection, indicating that B. cinerea induces senescence. The promoter of SAG12, as well as that of a second Arabidopsis senescence-associated gene, SAG13, whose expression is not specific to senescence, were previously analyzed in tomato plants and were found to be expressed
in a similar manner in the two species. These promoters were previously used in tomato plants to drive the expression of isopentenyl
transferase (IPT) from Agrobacterium to suppress leaf senescence (Swartzberg et al. in Plant Biology 8:579–586, 2006). In this study, we examined the expression
of these promoters following infection of tomato plants with B. cinerea. Both promoters exhibit high expression levels upon B. cinerea infection of non-senescing leaves of tomato plants, supporting our conclusion that B. cinerea induces senescence as part of its mode of action. In contrast to B. cinerea, Trichoderma harzianum T39, a saprophytic fungus that is used as a biocontrol agent against B. cinerea, induces expression of SAG13 only. Expression of IPT, under the control of the SAG12 and SAG13 promoters in response to infection with B. cinerea resulted in suppression of B. cinerea-induced disease symptoms, substantiating our prediction that delaying leaf senescence might reduce susceptibility to B. cinerea.
Contribution from the Agriculture Research Organization, The Volcani Center, Bet Dagan, Israel, No. 127/2006 series. 相似文献
10.
Organic management of soils is generally considered to reduce the incidence and severity of plant diseases caused by soil-borne
pathogens. In this study, take-all severity on roots of barley and wheat, caused by Gaeumannomyces graminis var. tritici, was significantly lower in organically-managed than in conventionally-managed soils. This effect was more pronounced on
roots of barley and wheat plants grown in a sandy soil compared to a loamy organically-managed soil. Fluorescent Pseudomonas spp. and in particular phlD+ pseudomonads, key factors in the take-all decline phenomenon, were represented at lower population densities in organically-managed
soils compared to conventionally-managed soils. Furthermore, organic management adversely affected the initial establishment
of introduced phlD+ P. fluorescens strain Pf32-gfp, but not its survival. In spite of its equal survival rate in organically- and conventionally-managed soils, the efficacy
of biocontrol of take-all disease by introduced strain Pf32-gfp was significantly stronger in conventionally-managed soils than in organically-managed soils. Collectively, these results
suggest that phlD+ Pseudomonas spp. do not play a critical role in the take-all suppressiveness of the soils included in this study. Consequently, the role
of more general mechanisms involved in take-all suppressiveness in the organically-managed soils was investigated. The higher
microbial activity found in the organically-managed sandy soil combined with the significantly lower take-all severity suggest
that microbial activity plays, at least in part, a role in the take-all suppressiveness in the organically-managed sandy soil.
The significantly different bacterial composition, determined by DGGE analysis, in organically-managed sandy soils compared
to the conventionally-managed sandy soils, point to a possible additional role of specific bacterial genera that limit the
growth or activity of the take-all pathogen. 相似文献
11.
G. Rodríguez Z. K. Punja 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(3):483-493
Wasabi (Wasabia japonica) is grown for its highly-valued rhizome which is used as a condiment in Japanese food. Symptoms of vascular blackening in
the rhizome were first observed in 2005 in plants grown in British Columbia, Canada. Microscopic observations and microbial
isolation from infected tissues revealed that most of the xylem tracheid cells were blackened and bacteria were consistently
associated with symptomatic plants. The bacterium most frequently recovered was identified as Pectobacterium carotovorum subsp. carotovorum (Pcc) using BioLog™ and sequencing of a specific ~510 bp IGS region. Pathogen-free plants obtained using meristem-tip micropropagation
were inoculated with a wasabi isolate of Pcc. Vascular blackening symptoms developed in the rhizome after 8 weeks when the rhizome was first wounded by stabbing or cutting,
or if the roots were pre-inoculated with Pythium species isolated from rhizome epidermal tissues, followed by inoculation with Pcc at 1 × 108 cells ml−1. Xylem tracheid cells were blackened and Pcc was reisolated from all diseased tissues. The highest frequency of rhizome vascular blackening occurred at 22°C and 27°C
and these tissues occasionally succumbed to soft rot at higher temperatures, but not when inoculated tissues were incubated
at 10°C. The rooting medium used by growers for vegetative propagation of wasabi was shown to contain Pcc but the pathogen was not recovered from the irrigation water. Entry of Pcc through wounds on wasabi rhizomes and the host tissue response result in symptoms of vascular blackening. 相似文献
12.
Fusarium species are soil-borne fungal pathogens that produce a variety of disease symptoms when attacking crop plants. The mode of root colonization of Eucalyptus viminalis seedlings by a pathogenic F. oxyporum strain (Foeu1) at the ultrastructural level and changes in cell wall pectin during host pathogen interactions are described. Root systems of E. viminalis plants were inoculated with F. oxysporum in an in vitro model system. Hyphae of F. oxysporum adhered to the outer epidermal cell walls through fibrillar material, and after penetration they spread into the internal tissues. They developed intercellularly and intracellularly in the root cortex and invaded vascular tissues. Papillae were induced, and the host plasma membrane ruptured in colonized cells, causing rapid host tissue and cell damage. Changes in distribution and occurrence of nonesterified and methyl-esterified pectins were evaluated after root colonization by F. oxysporum using two monoclonal antibodies, JIM 5 and JIM 7, respectively. Nonesterified pectin in control roots was mainly localized in the epidermal cell walls and middle lamellae in parenchymal cortex, whereas methyl-esterified pectin accumulated more in primary cell walls of the cortex and phloem. Decreases in immunodetected nonesterified and methyl-esterified pectins were associated with extensive plant tissue degradation after root colonization by the pathogenic fungus. 相似文献
13.
The distribution and multiplication of Ralstonia solanacearum in tomato plants of 11 resistant cultivars derived from different genetic sources and susceptible cultivar Ponderosa were examined. Bacterial multiplication in stems of resistant tomato plants was suppressed owing to the limitation of pathogen movement from the protoxylem or the primary xylem to other xylem tissues. The limitation was most conspicuous in Hawaii 7996. Grafting experiments indicated that the percentage of wilting of Ponderosa scions was less on Hawaii 7996 rootstocks than that on the most resistant rootstock (LS-89) used in Japan. Hawaii 7996 could be an alternative genetic source for breeding for resistance to bacterial wilt. 相似文献
14.
A new bacterial black spot disease was observed on Odontoglossum, Odontioda, Odontocidium, and Vuylstekeara orchids in Japan. Typical symptoms on the leaves were dark or black spots (or both) with a yellow halo. The causal agent was identified as Burkholderia andropogonis (Smith 1911) Gillis, Van Van, Bardin, Goor, Hebbar, Willems, Segers, Kersters, Heulin and Fernandez 1995. The isolates were pathogenic on four original host orchids, Phalaenopsis orchid, and tulip; they were not pathogenic on white clover or corn after needle stab inoculation. An antibiotic bactericide (oxytetracycline/streptomycin mixture WP) was most effective for controlling the disease. 相似文献
15.
The ability of selected strains of fluorescent Pseudomonas spp. to cause induced systemic resistance (ISR) in Eucalyptus urophylla against bacterial wilt caused by Ralstonia solanacearum was investigated. Four of the five strains used can produce salicylic acid (SA) in vitro and, therefore, chemical SA, that is known to induce resistance in many plant species, was used as a reference treatment.
Whereas a soil drench with SA did induce systemic resistance in E. urophylla, infiltration of SA into leaves did not. None of the fluorescent Pseudomonas spp. strains caused ISR against bacterial wilt when applied to the soil, but two strains, P. putida WCS358r and P. fluorescens WCS374r triggered ISR when infiltrated into two lower leaves 3–7 days before challenge inoculation. A mutant of strain WCS358r
defective in the biosynthesis of the fluorescent siderophore pseudobactin, did not cause ISR, while the purified siderophore
of WCS358r did, suggesting that pseudobactin358 is the ISR determinant of WCS358. A siderophore-minus mutant of WCS374r induced
the same level of disease resistance as its parental strain, but the purified siderophore induced resistance as well, indicating
that both the siderophore and another, unknown, inducing determinant(s) of WCS374r can trigger ISR in Eucalyptus. A possible role of WCS374r-produced SA remains uncertain. Transformation of a siderophore-minus mutant of WCS358 with the
SA biosynthetic gene cluster from WCS374 did not enable this transformant to cause ISR in E. urophylla. 相似文献
16.
Dry mycelium (DM) ofPenicillium chrysogenum and its water extract (DME) were examined for their effects on induced resistance against Verticillium wilt and plant growth
of cotton in the greenhouse. Soil application of 0.1–5% DM or 0.5–5% DME provided significant protection against the wilt,
relative to the control. As neither DM nor DME inhibited mycelial growth ofVerticillium dahliae in vitro, it is suggested that the disease-controlling effects of DM or DME are attributed to induced resistance. DME (5%), as well
as DME treated with chloroform or cold acetone, were as effective as 2% DM in reducing disease severity of Verticillium wilt,
implying that the resistance-inducing substance(s) in DM are mostly water-soluble, with neither proteins nor lipids likely
to be responsible for the induction of resistance. No significant difference in root colonization withV. dahliae was found between control-inoculated and 2% DM- or 5% DME-inoculated plants. However, colonization of hypocotyls and epicotyls
was drastically suppressed by either 2% DM or 5% DME relative to the control. Treatments with 2% DM or 5% DME significantly
increased ionically-bound peroxidase (POX) activity in roots, hypocotyls and the second leaf of cotton plants, with the hypocotyls
expressing the highest increase. Soil application of DM or DME increased plant height, fresh and dry weight of inoculated
and non-inoculated cotton plants, relative to their corresponding controls. It is concluded that DM may be used in cotton
crops to promote plant growth and to induce resistance againstV. dahliae. POX might be associated with the defense against Verticillium wilt.
http://www.phytoparasitica.org posting Jan. 9, 2002. 相似文献
17.
Hideshi Kawarazaki Yoshiyuki Nara Toshio Kijima Masao Goto 《Journal of General Plant Pathology》2008,74(1):94-95
A new leaf rot disease was found on the leaves of figmarigold (Lampranthus spectabile). The causal organism, identified as Pythium aphanidermatum was found to cause the same symptoms after artificial inoculation and was then reisolated from the inoculated plants. We
propose to name the disease Pythium rot of figmarigold. 相似文献
18.
19.
Miguel Angel Salas-Marina Miguel Angel Silva-Flores Edith Elena Uresti-Rivera Ernestina Castro-Longoria Alfredo Herrera-Estrella Sergio Casas-Flores 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(1):15-26
Trichoderma spp. are common soil fungi used as biocontrol agents due to their capacity to produce antibiotics, induce systemic resistance
in plants and parasitize phytopathogenic fungi of major agricultural importance. The present study investigated whether colonization
of Arabidopsis thaliana seedlings by Trichoderma atroviride affected plant growth and development. Here it is shown that T. atroviride promotes growth in Arabidopsis. Moreover, T. atroviride produced indole compounds in liquid cultures. These results suggest that indoleacetic acid-related indoles (IAA-related indoles)
produced by T. atroviride may have a stimulatory effect on plant growth. In addition, whether colonization of Arabidopsis roots by T. atroviride can induce systemic protection against foliar pathogens was tested. Arabidopsis roots inoculation with T. atroviride provided systemic protection to the leaves inoculated with bacterial and fungal pathogens. To investigate the possible pathway
involved in the systemic resistance induced by T. atroviride, the expression profile of salicylic acid, jasmonic acid/ethylene, oxidative burst and camalexin related genes was assessed
in Arabidopsis. T. atroviride induced an overlapped expression of defence-related genes of SA and JA/ET pathways, and of the gene involved in the synthesis
of the antimicrobial phytoalexin, camalexin, both locally and systemically. This is the first report where colonization of
Arabidopsis roots by T. atroviride induces the expression of SA and JA/ET pathways simultaneously to confer resistance against hemibiotrophic and necrotrophic
phytopathogens. The beneficial effects induced by the inoculation of Arabidopsis roots with T. atroviride and the induction of the plant defence system suggest a molecular dialogue between these organisms. 相似文献
20.
Incorporation into soil of dry mycelium ofPenicillium chrysogenum, a waste product of the pharmacological industry, enhanced plant growth and reduced root galling caused by the root-knot
nematodeMeloidogyne javanica in cucumber and tomato plants. Incorporation into sandy loam soil in pots of dry mycelium at a concentration of 0.25% (w/w)
resulted in complete protection of cucumber plants from the nematode. The number of juveniles recovered from soils containing
dry mycelium was greatly reduced even at a concentration of 0.1% (w/w). In microplot studies conducted at two sites in two
seasons, with three or four doses, dry mycelium caused a dose-dependent reduction in root galling index (GI) and promotion
of plant growth of cucumber and tomato plants. Inin vitro studies, the water extract of dry mycelium immobilized nematode juveniles and reduced the egg hatching rate, but these effects
were partly reversible after a rinse in water. Soil-drenching of cucumber and tomato seedlings with water extract of dry mycelium
did not reduce GI or number of root-invading juveniles. The results show that dry mycelium promotes plant growth and protects
plants against nematode infection. Protection, however, does not operatevia induced resistance.
http://www.phytoparasitica.org posting April 6, 2003. 相似文献