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1.
The insecticidal effects of pyrogallol were studied by treating eggs and larvae of the melon fruit fly, Bactrocera cucurbitae (Coquillett) (Tephritidae: Diptera), with various concentrations (1, 5, 25, 125, 625 and 3125 ppm) of the phenolic compound.
Although egg hatching decreased following treatment of 0–8-h old eggs with pyrogallol, the decrease was not significantly
different from the control. Larval period and total development period declined significantly in 64–72-h-old and 88–96-h-old
B. cucurbitae larvae fed on pyrogallol-treated diet. However, in the 44–48-h-old larvae, the larval period and total development period
were not affected by pyrogallol treatment at any of the tested concentrations. None of them survived up to the pupal stage
at the highest concentration. Number of pupae formed and adult emergence decreased significantly in all larval instars following
feeding on pyrogallol-treated diet. The analysis of enzymes in 64–72-h-old larvae treated with LC40 concentration (16.21 ppm) of pyrogallol at three time intervals, i.e., 24 h, 48 h and 72 h, showed significant induction in the activities of ascorbate peroxidase (APOX) and glutathione S-transferases
(GSTs) at 24 h but a decrease was observed following prolonged treatment. On the other hand, superoxide dismutase (SOD) and
peroxidases (POX) activity remained suppressed during the initial treatment interval but increased with prolonged treatment
in 136–144-h-old larvae. The catalase (CAT) activity was suppressed at all treatment durations whereas glutathione reductase
(GR) activity was not affected by pyrogallol treatment. An increase in the activities of ascorbate peroxidase, superoxide
dismutase, peroxidases and glutathione S-transferases indicates an induction of defensive response of the melon fruit fly
to the toxic effects produced by ingestion of pyrogallol. Although the effects of the compound on enzyme activity were tested
on second instar, it would be interesting to see the effects on other instars too. 相似文献
2.
Erika Valéria Saliba Albuquerque Poliene Martins Costa Ana Cristina Meneses Mendes Gomes Marcilene Santos Antonio Alves Pereira Michel Nicole Diana Fernandez Maria Fatima Grossi-de-Sa 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(3):365-373
Root-knot nematodes (RKN) are obligate parasite species of the genus Meloidogyne that cause great losses in Arabica coffee (Coffea arabica L.) plantations. Identification of resistant genotypes would facilitate the improvement of coffee varieties aiming at an
environmental friendly and costless nematode control. In this work, the C. arabica genotype ‘UFV 408-28’ was found to be resistant to the most destructive RKN species M. incognita. Pathogenicity assays indicated that the highly aggressive populations of M. incognita races 1, 2 and 3 were not able to successfully reproduce on ‘UFV 408-28’ roots and displayed a low gall index (GI = 2). An
average reduction of 87% reduction of the M. incognita population was observed on ‘UFV 408-28’ when compared to the susceptible cultivar ‘IAC 15’. By contrast, ‘UFV 408-28’ was
susceptible to the related species M. exigua and M. paranaensis (GI = 5 and 4, respectively). Histological observations performed on sections of UFV408-28 roots infected with M. incognita race 1 showed that nematode infection could be blocked right after penetration or during migration and establishment stages,
at 6 days, 7 days and 8 days after infection (DAI). Fluorescence and bright field microscopy observations showed that root
cells surrounding the nematodes exhibited HR-like features such as accumulation of phenolic compounds and a necrotic cell
aspect. In the susceptible ‘IAC 15’ roots, 6 DAI, feeding sites contained giant cells with a dense cytoplasm. Necrotic cells
were never observed throughout the entire infection cycle. The HR-like phenotype observed in the ‘UFV 408-28’—M. incognita interaction suggests that the coffee resistance may be mediated by a R-gene based immunity system and may therefore provide new insights for understanding the molecular basis of RKN resistance
in perennial crops. 相似文献
3.
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
4.
Tomasz Warzecha Andrzej Zieliński Edyta Skrzypek Tomasz Wójtowicz Maria Moś 《Phytoparasitica》2012,40(1):29-36
Vigor and selected physiological parameters (content of phenolic compounds, soluble sugars, chlorophyll a and b, and carotenoids)
of eight naked and two husked oat cultivars harvested at 15% moisture content were determined. Oat seeds were threshed using
two rotational speeds of the threshing drum: 1.6 m s−1 (LS) and 2.4 m s−1 (HS). They were then inoculated with a medium pathogenicity strain of Fusarium culmorum, strain IPO 348–01. In naked cultivars, the use of HS resulted in more severe mechanical damage; in consequence, seedling
vigor decreased by 16%. In naked cultivars chlorophyll a and b and carotenoids content were significantly reduced—by more
than 64%—when the HS was used. The inoculation caused over a 100% increase of carbohydrates in roots at LS but only a slight
increase at HS. Phenolic compound content was twice as high in roots than in leaves after inoculation for both LS and HS.
Area of microdamage and reduction of root fresh weight (f.wt.) are significantly correlated with biochemical parameters. Smaller
microdamage area and root f.wt. reduction are connected with higher physiological parameters, which confirms lower seedling
susceptibility to pathogen infection. 相似文献
5.
H. D. Mbouobda Fotso P. F. Djocgoue N. D. Omokolo I. El Hadrami T. Boudjeko 《Phytoparasitica》2010,38(1):71-79
The root rot disease caused by Pythium myriotylum is responsible for about 70% of cocoyam production loss in Cameroon. The potential of benzo-(1,2,3)-thiadiazole-7-carbothioic
S-methyl ester (BTH) to trigger resistance in cocoyam (Xanthosoma sagittifolium) plants against P. myriotylum was investigated. Under controlled conditions, BTH was an efficient elicitor of some defense reactions in cocoyam. Application
of 0.2 mg ml−1 of BTH on leaves 7 days before inoculation of roots with P. myriotylum enhanced the activities of peroxidase (Pox) and polyphenoloxidase (PPO) as well as the total phenolic content. This resistance
was noted as a decrease in disease incidence and severity in BTH-treated plants. This increase in Pox activities was correlated
with two new isoforms in a white (sensitive) cultivar inoculated after stimulation. In a yellow (resistant) cultivar, stimulation
was characterized by the appearance of one isoform. Qualitative analysis of phenolic compounds by HPLC showed an increase
of hydroxycinnamic and flavonoid derivatives after inoculation. We also observed the appearance of a new caffeoylshikimic
acid derivative after stimulation followed by inoculation of both cultivars. The findings indicated that the pattern of induction
is different and depends on the variety. 相似文献
6.
Adrien Gallou Sylvie Cranenbrouck Stéphane Declerck 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(2):219-230
Biological control of Rhizoctonia solani with Trichoderma harzianum has been demonstrated in several studies. However, none have reported the dynamics of expression of defence response genes.
Here we investigated the expression of these genes in potato roots challenged by R. solani in the presence/absence of T. harzianum Rifai MUCL 29707. Analysis of gene expression revealed an induction of PR1 at 168 h post-inoculation (hpi) and PAL at 96 hpi in the plants inoculated with T. harzianum Rifai MUCL 29707, an induction of PR1, PR2 and PAL at 48 hpi in the plants inoculated with R. solani and an induction of Lox at 24 hpi and PR1, PR2, PAL and GST1 at 72 hpi in the plants inoculated with both organisms. These results suggest that in the presence of T. harzianum Rifai MUCL 29707, the expression of Lox and GST1 genes are primed in potato plantlets infected with R. solani at an early stage of infection.
Mycothèque de l’Université catholique de Louvain of S. Cranenbrouck's affiliation is part of the Belgian Coordinated Collections
of Micro-organisms (BCCM). 相似文献
7.
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
8.
Phap Q. Trinh Wim M. L. Wesemael Sy T. T. Nguyen Chau N. Nguyen Maurice Moens 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(1):45-57
The pathogenicity and reproductive fitness of Pratylenchus coffeae and Radopholus arabocoffeae from Vietnam on coffee (Coffea arabica) seedlings cv. Catimor were evaluated in greenhouse experiments. The effect of initial population densities (Pi = 0, 1, 2,
4, 8, 16, 32, 64, 128, and 256 nematodes per cm3 soil) was studied for both species at different days after inoculation (dai). The data were adjusted to the Seinhorst damage
model Y = m + (1-m).zPi-T. Tolerance limit (T) for P. coffeae was zero for the height and the diameter of the coffee plants. For the diameter, the T-value for R. arabocoffeae was 25.6 for 30 and 60 dai and 12.8 for 90 and 120 dai. After 4 months T was zero. The low tolerance limits indicate that
Arabica coffee is highly intolerant to both nematode species. At the end of the experiment (180 dai), all plants were infected
and most were dead when inoculated with R. arabocoffeae at initial densities of 32, 64, 128 and 256 nematodes/cm3 soil. For P. coffeae plant death was already observed at the lowest inoculation densities. Growth of coffee was reduced at all inoculation levels
for both species. Pratylenchus coffeae and R. arabocoffeae caused intense darkening of the roots, leaf chlorosis and a strong reduction of root and shoot growth. It was observed that
P. coffeae mainly destroyed lateral roots rather than tap roots, whereas R. arabocoffeae reduced tap root length rather than the lateral roots. At the lowest inoculum densities, the reproduction factor of P. coffeae was 2.38 and 2.01 for R. arabocoffeae, indicating that arabica coffee is a host for both species. Plant growth as expressed by shoot height and shoot and root
weight measured 60 dai was negatively correlated with nematode (both species) density as expressed by the geometric mean of
nematode numbers at 30 and 60 dai. 相似文献
9.
The efficacy of a seed treatment of oilseed rape (OSR) (Brassica napus) with the rhizobacteria Serratia plymuthica (strain HRO-C48) and Pseudomonas chlororaphis (strain MA 342) applied alone or in combination against the blackleg disease caused by Leptosphaeria maculans was tested with different cultivars. Seeds were soaked in bacterial suspensions (bio-priming) to obtain log10 6–7 CFU seed−1. Cotyledons were inoculated with a 10 ul droplet of L. maculans spore suspension of log10 7 spores ml−1 and the disease index (size of lesions) was evaluated 14 days later. A mean disease reduction of 71.6% was recorded for S. plymuthica and of 54% for P. chlororaphis. The combined treatment was not superior to the treatment with S. plymuthica alone. The reduction of the disease caused by S. plymuthica was independent of the cultivar’s susceptibility, whereas the control effect recorded with P. chlororaphis increased with decreasing cultivar resistance to blackleg disease. The bacterial colonization of OSR was restricted to the
roots and hypocotyl. No significant difference in bacterial colonization of the rhizosphere was observed between different
cultivars, nor between single or combined bacterial seed treatments. 相似文献
10.
Yoshikatsu Genda Kyoko Sato Osamu Nunomura Tetsuo Hirabayashi Shinya Tsuda 《Journal of General Plant Pathology》2011,77(3):201-208
The location of Pepper mild mottle virus (PMMoV) within seeds as they developed on inoculated seedlings of pepper (Capsicum annuum) was followed over time by detecting the viral coat protein using immunofluorescence microscopy. Seedlings were inoculated
with PMMoV when the flower buds on the first and second branching nodes were in bloom. Fluorescence indicating the presence
of PMMoV was first observed around immature seeds and placentas in the ovaries on the fourth branching node at 20 days post-anthesis
(20 DPA), which corresponded to 39 days post-inoculation (39 DPI). The area with fluorescence gradually expanded from the
placenta into the integument and the parenchyma, and finally reached the tip of the immature seeds by 34 DPA (53 DPI). The
embryo or endosperm beyond the endothelium never fluoresced during the experiment [i.e., ending at 81 DPA (102 DPI)]. For
visualizing viral routes of invasion from seeds into new seedlings, PMMoV-infected C. annuum seeds that were heterozygous for the L
3
tobamovirus-resistance gene were sown in soil at 30°C. After ~2 weeks, the cotyledon developed virally induced necrosis.
These findings shed light on the infection cycle of PMMoV through vertical transmission in C. annuum. 相似文献
11.
Brahma N. Singh Akanksha Singh Satyendra P. Singh Harikesh B. Singh 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(1):121-134
Trichoderma harzianum is an effective biocontrol agent against the devastating plant pathogen Rhizoctonia solani. Despite its wide application in agriculture, the mechanisms of biocontrol are not yet fully understood. Mycoparasitism and
antibiosis are suggested, but may not be sole cause of disease reduction. In the present study, we investigated the role of
oxidant-antioxidant metabolites in the root apoplast of sunflower challenged by R. solani in the presence/absence of T. harzianum NBRI-1055. Analysis of oxidative stress response revealed a reduction in hydroxyl radical concentration (•OH; 3.6 times) at 9 days after pathogen inoculation (dapi), superoxide anion radical concentration (O2•−; 4.1 times) at 8 dapi and hydrogen peroxide concentration (H2O2; 2.7 times) levels at 7 dapi in plants treated with spent maize-cob formulation of T. harzianum NBRI-1055 (MCFT), as compared to pathogen-inoculated plants. The protection afforded by the biocontrol agent was associated
with the accumulation of the ROS gene network: the catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx)
and ascorbate peroxidase (APx), maximum activity of CAT (11.0 times) was observed at 8 dapi, SOD (7.0 times) at 7 dapi, GPx
(5.4 times) and APx (8.1 times) at 7 dapi in MCFT-treated plants challenged with the pathogen. This was further supported
by the inhibition of lipid and protein oxidation in Trichoderma-inoculated plants. MCFT stimulated the accumulation of secondary metabolites of phenolic nature that increased up to five-fold
and also exhibited strong antioxidant activity at 8 dapi, eventually leading to the systemic accumulation of phytoalexins.
These results suggest that T. harzianum–mediated biocontrol may be related to alleviating R. solani-induced oxidative stress. 相似文献
12.
Anne-Laure Boutigny Vessela Atanasova-Pénichon Marion Benet Christian Barreau Florence Richard-Forget 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(2):275-286
The effect of natural phenolic acids from wheat bran on type B trichothecene biosynthesis by Fusarium culmorum was investigated in vitro. Durum wheat bran contained various monomeric forms of phenolic acids, with ferulic acid being the most abundant. In addition,
various oligomeric forms of ferulic acid and mainly dimeric forms were also detected. When liquid cultures of F. culmorum were supplemented with a natural wheat bran extract, trichothecene production was fully inhibited. The exact mechanism by
which toxin synthesis is repressed remains to be clarified but we showed that the phenolic acid treatment resulted in a drastic
reduction in the expression level of structural trichothecene biosynthetic genes. The inhibitory efficiency of the natural
phenolic acid extract was significantly higher than that of a reconstituted mixture containing similar concentrations of monomeric
forms. Thus, to elucidate the full repression of type B trichothecene production induced by the natural phenolic acid extract
from wheat bran, two hypotheses can be raised: (i) a synergistic impact of monomeric and dimeric forms of phenolic acids,
(ii) the occurrence of an unidentified oligomeric form able to efficiently repress toxin yield. As a first attempt to investigate
the effect of oligomeric forms, one of the most abundant dimer of ferulic acid, the 8-5′-benzofuran dimer, has been synthesized
in vitro and was shown to inhibit trichothecene biosynthesis to the same extent than the monomer of ferulic acid. 相似文献
13.
Waseem Raza Xingming Yang Hongsheng Wu Yang Wang Yangchun Xu Qirong Shen 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(3):471-483
A bacterial strain was isolated from the rhizosphere of healthy watermelon plants in a heavily wilt-diseased field. This isolate
was tentatively identified as Paenibacillus polymyxa (SQR-21) based on biochemical tests and partial 16S rRNA sequence similarity. The purified antifungal compounds were members
of the fusaricidin group of cyclic depsipeptides having molecular masses of 883, 897, 947, and 961 Da with an unusual 15-guanidino-3-hydroxypentadecanoic
acid moiety, bound to a free amino group. The strain SQR-21 was not able to produce antifungal volatile compounds but was
able to produce cellulase, mannase, pectinase, protease, β-1,3-glucanase and lipase enzymes. However, the strain did not show
any chitinase activity. Biocontrol potential of this strain was evaluated against Fusarium oxysporum cause of Fusarium wilt disease of watermelon in a greenhouse experiment. This strain combined with organic fertiliser decreased
the disease incidence by 70% and increased the dry plant weight by 113% over the control. 相似文献
14.
The effects of some fungicides used against citrus diseases, on mycelial growth and conidial germination of Isaria farinosa (Holmsk.) Fries [Sordariomycetes: Hypocreales] and also on the pathogenicity of the fungus on citrus mealybug, Planococcus citri (Risso), were determined. Systemic fungicides such as tebuconazole, penconazole and nuarimol were the most effective as regards
both conidial germination and mycelial growth. Protective fungicides such as captan, chlorothalonil, mancozeb and propineb
inhibited conidial germination at between 1 and 5 μg ml−1 concentration, but captan, chlorothalonil and propineb did not inhibit the mycelial growth at 5,000 μg ml−1. Mancozeb inhibited mycelial growth between 2,500 and 5,000 μg ml−1. Sulphur and copper oxychloride did not inhibit the fungus even at very high concentrations. Sulphur, copper oxychloride,
fosetyl-al, chlorothalonil and carbendazim did not decrease the mortality percentage caused by I. farinosa. Tebuconazole, penconazole and mancozeb were the most effective and respectively reduced the mortality from 83% to 33%, 28%
and 30% in the ovisacs, from 81% to 29%, 27% and 29% in the 1st instar larvae, and from 84% to 34% in the adult females. 相似文献
15.
Eighteen toxins produced byFusarium species were tested at different concentrations onOrobanche ramosa seeds to evaluate their effectiveness in inhibiting germination. Many of the toxins were active at the highest concentration
used. Seven of them,viz. fusarenon X, nivalenol, deoxynivalenol, T-2 toxin, HT-2 toxin, diacetoxyscirpenol and neosolaniol, were highly active at
10μM, causing 100% inhibition of germination. Many of them were still active when assayed at a concentration ten times lower,
with T-2, HT-2, nivalenol, neosolaniol and diacetoxyscirpenol still able to cause total inhibition; the last mentioned was
very active also at 0.1μM, causing more than 90% inhibition. The results show that the use of toxic secondary metabolites could represent a useful
alternative strategy in the management of parasitic weeds, by interfering with the induced germination process, and that fungal
culture extracts could be an interesting source of new compounds acting as natural and original herbicides.
http://www.phytoparasitica.org posting Sept. 18, 2002. 相似文献
16.
Hamid Reza Pouralibaba Alejandro Pérez-de-Luque Diego Rubiales 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(1):53-63
Wilt disease of lentil caused by Fusarium oxysporum f.sp. lentis (Fol) is one of the most important diseases affecting lentil worldwide. Differential response of six lentil accessions with reported differences in the level of resistance to Fol was studied micro and macroscopically. Penetration took place through root epidermal cells without formation of any specific structure. Hyphae reached the stele within two days after inoculation (dai) and subsequently invaded xylem bundles having colonised the endodermis, vascular system and even vascular parenchyma phloem already by 4 dai. Resistance was observed as a quantitative trait in all studied accessions resulting from varying levels of xylem occlusion with gum-like substances and of degree of colonization observed only after 4 dai. An indication of a qualitative resistance was detected in accession BGE019696 inoculated with pathotype 1 as a fast secretion of phenolic compounds at 4 dai. Plasmolysis of cytoplasm, lignification and accumulation of phenolic compounds, gum-like substances and/or tyloses were observed from 15 to 30 dai. As a result of the various operative mechanisms, significantly lower numbers of propagules were recovered from roots by 15 dai, and a retardation of disease was measured as lower disease index by 30 dai in plants inoculated with pathotype 1, but not in those inoculated with pathotype 7. 相似文献
17.
Maria Pia Argentieri Trifone D’Addabbo Aldo Tava Augusta Agostinelli Marian Jurzysta Pinarosa Avato 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(2):189-197
The nematicidal activity of saponins from Medicago arborea (tops), M. arabica (tops and roots) and M. sativa (tops and roots) against the plant-parasitic nematode Xiphinema index was investigated. Nematicidal activity of related prosapogenins and sapogenins on X. index is also described. Saponins from Medicago spp. at different concentrations were all nematicidal, those from M. arborea tops being the less effective. In general, saponins induced 100% mortality at 500 μg ml−1 between 8 and 48 h, while prosapogenins resulted in toxicity starting at 125 μg ml−1. Differences in the effects on X. index induced by prosapogenins and sapogenins were less pronounced, although prosapogenins displayed a larger range of activity.
Assays with purified sapogenins demonstrated the relationship of the observed nematicidal activity of M. sativa and M. arborea to the content of the main aglycones (medicagenic acid and hederagenin, respectively) in the saponin extracts. Hederagenin
displayed the highest bioactivity, giving 38% mortality after 1 h at 125 μg ml−1. 相似文献
18.
Shohei Matsuura Yosuke Matsushita Reiko Kozuka Sachiko Shimizu Shinya Tsuda 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(1):111-115
Quantitative PCR revealed that Tomato chlorotic dwarf viroid (TCDVd) was present in substantial amounts in viroid-infected tomato flowers. Healthy tomato plants were arranged in two
different glasshouses, and plants were mechanically inoculated with TCDVd. Bumblebees (Bombus ignitus) were then introduced into the glasshouses to reveal whether the viroid was transmitted from infected source plants to neighbouring
healthy plants. TCDVd infection was found in neighbouring tomato plants more than 1 month after the introduction of the bees,
some of which expressed symptoms, in both glasshouses. Thus, bumblebees transmitted TCDVd from tomato to tomato by pollination
activities. 相似文献
19.
Sunflower chlorotic mottle virus (SuCMoV) is a recently described potyvirus that causes systemic infections in sunflower plants leading to chlorotic mottling
and important growth reductions and yield losses. Oxidative damage is expressed after symptom development in this host-pathogen
combination. The involvement of antioxidant enzyme activities in disease susceptibility was studied in two sunflower lines
differing in the intensity and rate of development of SuCMoV infections: L2 is more susceptible than L33. A transient superoxide
production peak was detected in leaves of both lines before symptom development. H2O2 accumulation increased before symptom expression in infected plants of L33 but in L2 such increase was registered only after
symptoms became evident. In healthy plants of both lines, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase
(APX) showed similar activity levels. In inoculated plants of line L2, but not in L33, SOD and CAT activities increased significantly
before the appearance of symptoms, and APX increases were detected later. A 1 mM SA treatment effectively decreased SuCMoV
accumulation in plants of L2 but it did not affect it in L33. This treatment increased H2O2 accumulation and prevented the increase in antioxidant enzyme activities in infected plants of L2. It is suggested that increases
in antioxidant enzyme activities interrupted the signals generated by the increase in ROS, which may have otherwise triggered
defence reactions in the host and thus, resulted in a compatible interaction. 相似文献
20.
Susanne Vogelgsang Michael Sulyok Andreas Hecker Eveline Jenny Rudolf Krska Rainer Schuhmacher Hans-Rudolf Forrer 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(2):265-276
In a field experiment between 2004 and 2006, 14 winter wheat varieties were inoculated with either a mixture of three isolates
of F. poae or a mixture of three isolates of F. avenaceum. In a subsequent climate chamber experiment, the wheat variety Apogee was inoculated with individual single conidium isolates
derived from the original poly conidium isolates used in the field. Disease symptoms on wheat heads were visually assessed,
and the yield as well as the fungal incidence on harvested grains (field only) was determined. Furthermore, grains were analysed
using LC-MS/MS to determine the content of Fusarium mycotoxins. In samples from field and climate chamber experiments, 60 to 4,860 μg kg−1 nivalenol and 2,400 to 17,000 μg kg−1 moniliformin were detected in grains infected with F. poae and F. avenaceum, respectively. Overall, isolate mixtures and individual isolates of F. avenaceum proved to be more pathogenic than those of F. poae, leading to a higher disease level, yield reductions up to 25%, and greater toxin contamination. For F. poae, all variables except for yield were strongly influenced by variety (field) and by isolate (climate chamber). For F. avenaceum, variety had a strong effect on all variables, but isolate effects on visual disease were not reflected in toxin production.
Correlations between visual symptoms, fungal incidence, and toxin accumulation in grains are discussed. 相似文献