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1.
The mechanism by which some plant species develop resistance to the root parasite, broomrape ( Orobanche aegyptiaca ), is still not clear. Resistance to other pathogens can be induced by methyl jasmonate and systemic acquired resistance can be induced by treatment with salicylic acid, while cis -jasmone can act as a signaling molecule in plant–insect interactions. The three compounds studied, methyl jasmonate, cis -jasmone, and methyl salicylate, were applied to Arabidopsis thaliana seedlings that were then transferred to Nunc cell culture plates and exposed to the germinating seeds of O. aegyptiaca . The number of infections of the roots of single seedlings of A. thaliana was then quantified. Exposure for 24 h to very low concentrations of methyl jasmonate or methyl salicylate, which were then removed, effectively induced resistance to infection of A. thaliana by O. aegyptiaca , reducing attachment and tubercle formation by 90%. cis -Jasmone was far less effective in inducing a similar resistance to infection. These results support the view that methyl jasmonate can induce almost full resistance to infection by broomrape. The fact that such resistance is not observed under normal conditions of infection supports the idea that the root parasite does not evoke the full defensive response in the host plant. 相似文献
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P. Letousey A. de Zélicourt C. Vieira Dos Santos S. Thoiron F. Monteau P. Simier P. Thalouarn P. Delavault 《Plant pathology》2007,56(3):536-546
Resistance to the dicotyledenous parasite Orobanche cumana in sunflower is characterized by a low number of parasitic attachments and a confinement of the parasite in host tissues leading to its necrosis. To help understand what determines such resistance mechanisms, molecular, biochemical and histological approaches were employed before (early response) and after (late response) attachment of the broomrape parasite to susceptible (2603) and resistant (LR1) sunflower genotypes. The expression patterns of 11 defence-related genes known to be involved in different metabolic pathways (phenylpropanoids, jasmonate, ethylene) and/or in resistance mechanisms against microorganisms were investigated. RT-PCR and cDNA blot experiments revealed that the resistant genotype exhibited a stronger overall defence response against O. cumana than the susceptible one, involving marker genes of the jasmonate (JA) and salicylic acid (SA) pathways. Among them, the SA-responsive gene, def. (defensin), appeared to be characteristic of LR1 sunflower resistance. However, no JA accumulation and similar SA contents (250–300 ng g−1 FW) were measured by GC/MS in both genotypes, parasitized or not. In addition, three cDNAs, isolated by a suppression-subtractive hybridization, were shown to be strongly induced only in the resistant genotype 8 days post-inoculation, when the first O. cumana attachments occurred. These genes, putatively encoding a methionine synthase, a glutathione S-transferase and a quinone oxidoreductase, might be involved in detoxification of reactive oxygen species, suggesting the occurrence of an oxidative burst during the incompatible interaction. Finally, host cell-wall modifications leading to parasite-confinement were correlated with more intense callose depositions in the resistant genotype, concomitant with over-expression of the callose synthase cDNA HaGSL1 . 相似文献
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M A DITA J V DIE† B ROMÁN† F KRAJINSKI‡ H KÜSTER§ M T MORENO† J I CUBERO# & D RUBIALES 《Weed Research》2009,49(S1):66-80
Orobanche crenata is a root parasitic weed that is a major constraint for grain and forage legume cultivation in Mediterranean and West Asia. Only moderate to low levels of incomplete resistance of complex inheritance has been identified so far in legume crops, which has hampered genetic and genomic analysis. In the present study, we provide a gene expression profile of roots of the model legume Medicago truncatula in response to infection by O. crenata . M. truncatula accessions SA27774 (complete resistance acting at early penetration stages) and SA4087 (incomplete late acting resistance mediated by necrosis of parasite tubercle) were inoculated with O. crenata seeds in a semi-sterile dish system. Roots were harvested at 15 (first contacts of the parasitism structures with the host roots), 21 (initial stage of parasite tubercle formation on SA4087) and 35 (prior necrosis of well-developed parasite tubercle of on SA4087) days post-inoculation. Array hybridisations revealed several hundred genes up-regulated in response to O. crenata infection. Gene expression patterns suggest that resistance mechanisms activated in both genotypes are temporally and spatially different and resemble those associated with plant resistance to microbial pathogens. Regulated genes identified here represent a comprehensive resource that can be used as a support to breeding strategies for resistance. 相似文献
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Quantitative determinations of chlorophyll showed that Cuscuta hyalina and Striga hermonthica possess chlorophyll. No trace of chlorophyll was found in Orobanche ramosa. Autoradiographic evidence showed that both radiocarbon and radiophosphorous moved from host to parasite in alt three species. Photosynthesis occurs in S. hermonthica when the parasite is isolated from its host. The adventitious roots of S. hermonthica and O. ramosa appear to be functional in absorbing a proportion of the required inorganic substances and water. S. hermonthica is a hemiparasite, O. ramosa is a holoparasite but C. hyalina is best described as a partial parasite. 相似文献
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The mechanism by which the flowering holoparasitic plant, Orobanche aegyptiaca , infects its host without evoking a defence mechanism is still poorly understood. In this work, we studied several mechanisms used by phytopathogenic fungi. We focussed on the possible role of peroxidases during O. aegyptiaca penetration into the roots of Arabidopsis thaliana . A convenient experimental system for studying the interaction under sterile conditions was developed. The formation of extracellular reactive oxygen species (ROS) was detected at the interaction site before, during, and after the parasite penetrated into the host. These extracellular ROS probably originated from the parasite. However, no intracellular ROS could be detected at the site of the interaction. Peroxidase activity was observed mainly at the apex of the root of the parasite and in the adventitious roots of the tubercle. Benzhydroxamic acid, a peroxidase inhibitor, was used to probe the possible role of peroxidase in the infection process. Peroxidase activity was observed in the root apex and adventitious roots of O. aegyptiaca, but no evidence was found for its participation in the actual infection process. Peroxidase activity was also found in the later stages of the interaction between the host and the parasite. We propose that peroxidases could have a role in generating extracellular ROS for loosening the cell wall of the host in order to facilitate penetration. Alternatively, the ROS could act in facilitating the root elongation of the parasite. 相似文献
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Kyutaro Kishimoto Kenji Matsui Rika Ozawa Junji Takabayashi 《Journal of General Plant Pathology》2007,73(1):35-37
1-Octen-3-ol is a major volatile metabolite produced by mold fungi. When Arabidopsis plants were treated with 1-octen-3-ol,
some defense genes that are turned on by wounding or ethylene/jasmonic acid signaling were induced. The treatment also enhanced
resistance of the plant against Botrytis cinerea. When the induction of defense genes with 1-octen-3-ol was compared with that by volatile methyl jasmonate (MeJA) and methyl
salicylate treatments, the induction pattern was similar to that caused by MeJA. Thus, Arabidopsis seems to recognize 1-octen-3-ol
and consequently activates its defense response. 相似文献
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Root parasitic plants of the family Orobanchaceae cause severe damage to important agricultural crops worldwide. These parasitic weeds are difficult to control since most of their lifecycle occurs belowground. This hinders the diagnosis of infection and normally when irreversible damage has been caused to the crop. Therefore, new and more effective control strategies against these parasitic weeds should be focused on the initial stages of the interaction. Using tomato-Phelipanche ramosa as model system, we have explored the host response during the initial phase of parasitic infection by monitoring the expression of marker genes of different defense-related hormonal pathways. Two different colonization stages were selected and analyzed by quantitative real-time PCR. The data suggest that the three principal defense regulating hormonal pathways - salicylic acid (SA), jasmonic acid (JA) and abscisic acid (ABA) - are induced after infection, being therefore, likely involved in the defense response against these root parasites. In addition, an induction of the strigolactone (SL) biosynthesis genes SlD27 and SlCCD8 was observed. Our results suggest a complex regulation of plant defenses during the early stages of plant-parasite interaction involving the classical defense hormones, and suggest an additional role of the parasite germination stimulants SLs at this post-attachment stage. 相似文献
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Takahashi H Ishihara T Hase S Chiba A Nakaho K Arie T Teraoka T Iwata M Tugane T Shibata D Takenaka S 《Phytopathology》2006,96(8):908-916
ABSTRACT The biocontrol agent Pythium oligandrum produces glycoprotein elicitor in the cell wall fraction, designated CWP, and induces resistance to a broad range of pathogens. To understand the mechanism of CWP-induced resistance to pathogens, gene expression at the early stage of CWP treatment in tomato roots was analyzed using a cDNA array. At 4 h after CWP treatment, 144 genes were up-regulated and 99 genes were down-regulated. In the 144 up-regulated genes, nine genes exhibited about eightfold increased expression. Analysis of the response of these nine genes to three commercial plant activators indicated that a high level of one gene, beta-cyanoalanine synthase gene (LeCAS) encoding hydrogen cyanide (HCN) detoxification enzyme, was stably induced in tomato roots by such treatment. However, expression of LeCAS was not significantly induced in tomato roots at 4 h by abiotic stresses, whereas only a very low level of induction of such expression by cold stress was observed. This LeCAS expression was also induced after exogenous treatment with a low level of 1-amino-cyclopropane-1-carboxylate as the precursor of ethylene, but not with either salicylic acid or methyl jas-monate. The induction of LeCAS expression in CWP-treated and plant activator-treated roots is likely to be caused by the detoxification of HCN during ethylene production. Transient activation of LeCAS expression caused by ethylene production in tomato roots may be a general phenomenon in fungal elicitor-induced and synthetic plant activator-induced resistance. LeCAS seems to be useful for screening possible novel plant activators for plant protection against pathogens. 相似文献
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Summary Six inhibitors acting at different stages of gibberellin biosynthesis, applied during conditioning of Orobanche ramosa seeds, reduced subsequent germination in the presence of GR24 (a strigol analogue). Ethylene seems to be involved in the induction of germination of conditioned seeds by GR24 , as inhibitors of its synthesis or action, applied to conditioned seeds, also strongly reduced induction of germination by GR24 . Exogenous ethylene did not induce germination of conditioned seeds, but 2-chloroethylphosphonic acid was able to do so. When inhibitors of gibberellin biosynthesis were applied to conditioned seeds in the presence of GR24 , they inhibited germination. These same inhibitors also strongly inhibited germination of conditioned Striga hermonthica seeds in response to GR24 ; this inhibitory effect was reversed by the addition of 2-chloroethylphosphonic acid. The effect of these inhibitors on S. hermonthica , in which ethylene is a necessary mediator of germination induction by GR24 , strongly suggests that ethylene synthesis is also required for the induction of O. ramosa seed germination by GR24 . These growth regulators, which inhibit the two steps of germination in O. ramosa , could be useful for the development of methods for early season control of this parasite. 相似文献
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Rosalía Núñez-Pastrana Guadalupe Fabiola Arcos-Ortega Ramón Armando Souza-Perera Carlos Alberto Sánchez-Borges Yumi Elena Nakazawa-Ueji Francisco Javier García-Villalobos Adolfo Alberto Guzmán-Antonio José Juan Zúñiga-Aguilar 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(4):669-683
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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
17.
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
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Certain hypovirulent Rhizoctonia isolates effectively protect plants against well-known important pathogens among Rhizoctonia isolates as well as against other pathogens. The modes of action involved in this protection include resistance induced in plants by colonization with hypovirulent Rhizoctonia isolates. The qualifications of hypovirulent isolates (efficient protection, rapid growth, effective colonization of the plants, and easy application in the field) provide a significant potential for the development of a commercial microbial preparation for application as biological control agents. Understanding of the modes of action involved in protection is important for improving the various aspects of development and application of such preparations. The hypothesis of the present study is that resistance pathways such as systemic acquired resistance (SAR), induced systemic resistance (ISR), and phytoalexins are induced in plants colonized by the protective hypovirulent Rhizoctonia isolates and are involved in the protection of these plants against pathogenic Rhizoctonia. Changes in protection levels of Arabidopsis thaliana mutants defective in defense-related genes (npr1-1, npr1-2, ndr1-1, npr1-2/ndr1-1, cim6, wrky70.1, snc1, and pbs3-1) and colonized with the hypovirulent Rhizoctonia isolates compared with that of the wild type (wt) plants colonized with the same isolates confirmed the involvement of induced resistance in the protection of the plants against pathogenic Rhizoctonia spp., although protection levels of mutants constantly expressing SAR genes (snc1 and cim6) were lower than that of wt plants. Plant colonization by hypovirulent Rhizoctonia isolates induced elevated expression levels of the following genes: PR5 (SAR), PDF1.2, LOX2, LOX1, CORI3 (ISR), and PAD3 (phytoalexin production), which indicated that all of these pathways were induced in the hypovirulent-colonized plants. When SAR or ISR were induced separately in plants after application of the chemical inducers Bion and methyl jasmonate, respectively, only ISR activation resulted in a higher protection level against the pathogen, although the protection was minor. In conclusion, plant colonization with the protective hypovirulent Rhizoctonia isolates significantly induced genes involved in the SAR, ISR, and phytoalexin production pathways. In the studied system, SAR probably did not play a major role in the mode of protection against pathogenic Rhizoctonia spp.; however, it may play a more significant role in protection against other pathogens. 相似文献
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C.A. Moreno F. Castillo A. González D. Bernal Y. Jaimes M. Chaparro C. González F. Rodriguez S. Restrepo A.M. Cotes 《Physiological and Molecular Plant Pathology》2009,74(2):111-120
Tomato-Fusarium oxysporum f.sp. radicis-lycopersici pathosystem was used to study induced systemic resistance elicited by Trichoderma koningiopsis (Th003) using the split root model. The ability of the antagonist to promote plant growth was also established. Stem colonization by the pathogen was significantly reduced in treated plants. The induction of resistance was enhanced 6 days after elicitation and when the antagonist was used in a concentration of 105 conidia per ml. Th003 application in seed priming and nursery significantly stimulated plant growth. Gene expression induced by Th003 was evaluated using the tomato TOM1 microarray. Plant treatment with T. koningiopsis affected mRNA levels of 45 genes: 41 in roots and 4 in leaves. Of particular interest was the induction of genes involved in the jasmonic and ethylene transduction pathways found in the microarray analysis and qRT-PCR, which suggest a temporary increment of defense related gene expression response to T. koningiopsis Th003. 相似文献