共查询到20条相似文献,搜索用时 15 毫秒
1.
B. Osterroht 《European journal of plant pathology / European Foundation for Plant Pathology》1968,74(1):105-111
Tissue browning and wilting ofFusarium-infected tomato plants were suppressed by rufianic acid. However, calcium proved to be necessary for the action of rufianic acid as a therapeutant. An interrelationship between the effects of Ca supply and of rufianic acid on wilt disease in tomato plants and on growth was demonstrated.The amino acid contents of the exudates of decapitated plants and the Ca supply were found to be inversely related. Rufianic acid caused a decrease in the concentration of amino acids in exudates of infected as well as of healthy plants.In several respects rufianic acid kept infected plants in a near normal condition. 相似文献
2.
Malgorzata Golanowska Joanna Kielar Ewa Lojkowska 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(4):803-817
Pectinolytic bacteria from the genus Dickeya (former Erwinia chrysanthemi), belonging to Dickeya dianthicola and Dickeya solani species, are causative agents of blackleg and soft rot diseases in Europe. Recently, D. solani have been isolated most frequently from potato plants with the symptoms of blackleg and soft rot. D. solani strains were shown to cause more severe disease symptoms on potato plants than D. dianthicola especially at the higher temperature. They are also able to develop blackleg disease from lower inoculum levels. In the presented study we not only compared phenotypic features of fifteen D. solani strains isolated in countries having different climatic conditions, Poland, Finland and Israel, but also we examined three D. dianthicola strains. The comparison was performed to determine the influence of the strain origin and the temperature of incubation on the ability of the strains to macerate potato tissue and on their major virulence factors such as: pectinolytic, cellulolytic and proteolytic activities, siderophore production and motility. Polish D. solani strains showed higher activities of cell wall degrading enzymes than the Finnish and Israeli strains at all the tested temperatures: 18, 27, 37 °C. This observation is correlated with the higher ability of Polish D. solani strains to cause soft rot. In addition, D. solani strains exhibited higher activity of the above mentioned enzymes and caused more severe potato tuber maceration in laboratory tests than the tested D. dianthicola strains. The collected results indicate that although D. solani strains from different climatic conditions have identical Pulse Field Gel Electrophoresis (PFGE) profiles in addition to the same fingerprint profiles obtained by the repetitive sequence-based polymerase chain reaction (REP, ERIC and BOX repetitive sequences), they differ in the examined phenotypic features, especially in the activities of pectinolytic, cellulolytic and proteolytic enzymes and their capacity to macerate potato tuber tissue. 相似文献
3.
Domenico Rongai Patrizio Pulcini Barbara Pesce Filomena Milano 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(1):229-238
Pomegranate (Punica granatum) is an important source of bioactive compounds and has been used in folk medicine for many centuries. This paper describes the in vitro antifungal activity of pomegranate peel aqueous extract (pae) on the development of Fusarium wilt of tomato caused by Fusarium oxysporum, f. sp. lycopersici. HPLC-DAD-ESI/MS analysis was performed to identify punicalagins and ellagic acid, which are the main antifungal compounds. In vivo tests established the efficacy of pae treatments in controlling Fusarium wilt by evaluating improvements in growth variables of tomato plants. At high concentrations, pae showed allelopathic activity in tomato plants. The germination and the radicle growth of tomato seeds were significantly affected by pae. Increasing the extract concentration led to a progressive decrease in germination and in the length of the radicle. The reduction of the Fusarium population in soil and the increase in number of healthy plants obtained as a result of pae treatments indicate that this plant extract could have an important role in biologically-based management strategies for the control of Fusarium wilt in tomato crops. 相似文献
4.
Seong-Mi Jo Yu Ayukawa Sung-Hwan Yun Ken Komatsu Tsutomu Arie 《Journal of General Plant Pathology》2018,84(6):395-398
RNA silencing pathways in filamentous fungi are composed of multiple component proteins and known to be involved in vegetative growth, virulence or sexual reproduction. We found that the tomato wilt fungus, Fusarium oxysporum f. sp. lycopersici (Fol), carries four homologues genes of Qde-2, an argonaute protein gene and one of the main component protein genes in Neurospora crassa. Gene targeting revealed that FoQde-2, one of the Qde-2 homologues in Fol, is involved in virulence to tomato but not in vegetative growth. 相似文献
5.
Stuti Patel Meenu Saraf 《European journal of plant pathology / European Foundation for Plant Pathology》2017,149(2):425-433
Plant growth promoting Bacillus subtilis MSS9 and Bacillus licheniformis MSS14 were isolated from the tomato rhizosphere. These isolates were capable of inhibiting the fungal pathogen, Fusarium oxysporum f. sp. lycopersici causing fusarium wilt in tomato, tested by dual culture method and by mycolytic enzyme production. The isolates have the capacity to form biofilm on the microtitre plate. Scanning electron microscopy revealed good colonization capacity of Bacillus licheniformis MSS14 on tomato plant root as compared to Bacillus subtilis MSS9, pot experiments were also analyzed to study the effects of both rhizobacterial cultures on pathogen development and plant growth. It was observed that MSS14 reduces the incidence of Fusarium oxysporum f. sp. lycopersici in tomato and there was significant increase in vegetative parameters like root length, shoot length, plant wet weight, dry weight and chlorophyll content after which indicates that the root colonization property of the culture MSS14 helps in enhancing the biocontrol capacity against pathogen than that of MSS9. 相似文献
6.
K. Scholte 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(2):93-101
Effects of crop rotation on the incidence of soil-borne pathogens and on the performance of potato were investigated in five field experiments. Rotations differed in cropping frequency of potato and in crop sequence.Incidence of stem canker caused byRhizoctonia solani was strongly influenced by the cropping frequency of potato and not by crops with which the potato was alternated in the rotation. Cropping frequency of potato also affected the occurrence of black scurf, but less pronounced than for stem canker. The antagonistVerticillium bigutatum slightly reducedR. solani (black scurf) in plots on sandy soil continuously cropped with potato. Incidence of stem canker was also strongly affected by granular nematicides applied to the soil, nitrogen level and the cultivar grown.Stem infections byVerticillium dahliae depended on the cropping frequency of potato, by the crop with which the potato was alternated in the rotation and by the density and virulence of endoparasitic nematodes, especiallyMeloidogyne spp.Crop rotation had no effect at all on incidence of common scab on tubers, whereas the effect of cropping frequency of potato on netted scab was highly significant. When cultivars were grown susceptible to both scab types, netted scab supressed common scab. 相似文献
7.
Younes M. Rashad Abdulaziz A. Al-Askar Khalid M. Ghoneem Wesam I. A. Saber Elsayed E. Hafez 《Phytoparasitica》2017,45(2):227-237
Streptomyces griseorubens E44G is a chitinolytic bacterium isolated from cultivated soil in Saudi Arabia (a hot, arid climatic region). In vitro, antifungal potential of S. griseorubens E44G was assessed against the phytopathogenic fungus, Fusarium oxysporum f. sp. lycopersici (the causative agent of the Fusarium wilt disease of tomato). An inhibition zone of 24 mm was recorded. The chitinolytic activity of S. griseorubens E44G was proved when the colloidal chitin agar plate method was used. A thermostable chitinase enzyme of 45 kDa molecular weight was purified using gel filtration chromatography. The optimum activity was obtained at 60 °C and pH 5.5. The purified enzyme has shown a very pronounced activity against the phytopathogenic fungus, F. oxysporum. The molecular characterization of the chitinase gene indicated that it consists of 1218 bp encoding 407 amino acids. The phylogentic analysis based on the nucleotide DNA sequence and the deduced amino acids sequence showed high similarity percentages with other chitinases isolated from different Streptomyces species. In the field evaluation, application of both S. griseorubens E44G treatments significantly increased all tested growth and yield parameters and decreased the disease severity compared with the infected-untreated tomato plants suggesting potential as a biocontrol agent. 相似文献
8.
Elena Fanelli Alberto Troccoli Francesco Capriglia Giuseppe Lucarelli Nicola Vovlas Nicola Greco Francesca De Luca 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(2):355-369
Tomato bacterial canker and wilt disease caused by Clavibacter michiganensis subsp. michiganensis (Cmm) is among one of the major bacterial diseases associated with tomato (Solanum lycopersicum L.) in the western Mediterranean region of Turkey. A total of 118 Cmm isolates were obtained from the petiole and the main vein of leaves of different cultivars of diseased tomato plants, and these isolates were cultured in semiselective medium (mSCM). The identity of Cmm isolates was confirmed through gas chromatography-fatty acid methyl-esters (GC-FAME) analysis and polymerase chain reaction (PCR) using the primers, CMM5 and CMM6. The fatty acid analysis of all the Turkish isolates yielded major components that included anteisoheptadeconic acid (a15:0), palmitic acid (i16:0) and anteisoheptadeconic acid (a17:0); the analysis detected and categorized all the isolates into 10 different FAME groups. Among repetitive element sequence PCR (rep-PCR) analysis, Box primer yielded the most reproducible genomic profiles with band sizes that ranged from ~200 bp to 2 kb. The isolates were also separated into 12 groups by pulsed-field gel electrophoresis (PFGE) after digesting the total genomic DNA with SpeI, a rare cutting enzyme. The genome sizes of the different strains of Cmm were also determined after running unrestricted total genomic DNA, which yielded average values between 3.0 and 3.5 MB. All the Cmm isolates had pCM1 and pCM2 plasmids. This is the first report on the detailed characterization of the Cmm population in Turkey. 相似文献
9.
S. Landschoot M. Vandecasteele J. Carrette B. De Baets M. Höfte K. Audenaert G. Haesaert 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(3):657-672
Early blight and brown spot, caused by respectively Alternaria solani and Alternaria alternata, can lead to severe yield losses in potato-growing areas. To date, fungicide application is the most effective measure to control the disease. However, in recent years, a reduced sensitivity towards several active ingredients has been reported. To shed light on this issue, Alternaria isolates were collected from different potato fields in Belgium during two growing seasons. Subsequently, the sensitivity of these isolates was assessed using four widely used fungicides with different modes of action. Demethylation inhibitors, quinone outside inhibitors, a dithiocarbamate and a carboxylic acid amide were included in this study. Although all fungicides reduced spore germination and vegetative growth of Alternaria species to some extent, the interspecies sensitivity was very variable. In general, A. solani was more suppressed by the fungicides compared to A. alternata. The effectiveness of the dithiocarbamate mancozeb was high, whereas the quinone outside inhibitor azoxystrobin showed a limited activity, especially towards A. alternata. Therefore, a subset of the A. alternata and A. solani isolates was tested for the presence of, respectively, the G143A substitution and the F129L substitution in the cytochrome b. The frequency of A. alternata isolates bearing the resistant G143A allele (approximately 65%) was comparable in both sampling years, although sensitivity of isolates decreased during the growing season. This finding points to a shift of the population towards resistant isolates. Both the European genotype I and American genotype II were present in the A. solani population, with genotype I being the most prevalent. None of the genotype I isolates carried the F129L substitution, whereas in 83% of the genotype II isolates this substitution was present. Our results demonstrate for the first time that the Belgian Alternaria population on potato comprises a considerable broad spectrum of isolates with different sensitivity to fungicides. 相似文献
10.
Julio C. Barbosa Sarah S. Barreto Alice K. Inoue-Nagata Marcelo S. Reis Ana Carolina Firmino Armando Bergamin Filho Jorge Alberto Marques Rezende 《Journal of General Plant Pathology》2009,75(6):440-443
Nicandra physaloides, a common weed in South America, was found to be infected by an isolate of Tomato severe rugose virus (ToSRV), a bipartite begomovirus. The plants developed severe yellow rugose mosaic and were collected in São Paulo State, Brazil. This isolate of ToSRV was transmitted by Bemisia tabaci B biotype from infected plants of N. physaloides to healthy plants of N. physaloides and tomato in a glasshouse. This is the first report of natural infection of N. physaloides by ToSRV in Brazil. 相似文献
11.
M. C. M. Pérombelon 《European journal of plant pathology / European Foundation for Plant Pathology》1992,98(2):135-146
Blackleg is caused byErwinia carotovora subsp.atroseptica (Eca) andE. chrysanthemi (Echr) in cool and hot climates respectively. The bacteria are opportunistic pathogens and rely on their strong pectolytic character to infect plants when conditions favor their multiplication. Blackleg is a seedborne disease and the bacteria can survive in a quiescent form in lenticels and wounds during storage. The contaminated mother tuber and not the blackleg plant is the main source of progeny tuber contamination. Other sources of the pathogen are airborne (insects and aerosols) erwinias deposited on leaves and from there to the soil and progeny tubers, and erwinias in rotting tubers smeared into wounds incurred during mechanical crop handling.Most seed tubers are contaminated but blackleg incidence is related to seed contamination level modulated by soil water status. Competitiveness of the erwinias in the rotting mother tuber is affected by temperature, Eca is favored at <25°C and Echr at higher temperatures. The ubiquitousE. carotovora subsp.carotovora apparently fails to compete successfully with the other erwinias and saprophytic pectolytic bacteria in mother tubers and therefore does not cause blackleg.Disease control measures are based on avoiding tuber contamination by cultural means (early harvesting), reducing tuber contamination level (dry storage and hot water treatment) and planting ‘clean’ seed identified by quantifying tuber contamination rather than by visual crop inspection. Finally, recently identified highly resistant, even under anaerobic conditions, wildSolanum spp. could be used to breed for resistant cultivars by conventional methods or by genetic engineering. 相似文献
12.
Juha Kaitera Ritva Hiltunen Tuomas Kauppila Jarkko Hantula 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(2):367-377
Fusarium is one of the most destructive fungal genera whose members cause many diseases on plants, animals, and humans. Moreover, many Fusarium species secrete mycotoxins (e.g. trichothecenes and fumonisins) that are toxic to humans and animals. Fusarium isolates from date palm trees showing disease symptoms, e.g. chlorosis, necrosis and whitening, were collected from seven regions across Saudi Arabia. After single-sporing, the fungal strains were morphologically characterized. To confirm the identity of morphologically characterized Fusarium strains, three nuclear loci, two partial genes of translation elongation factor 1 α (tef1α) and β-tubulin (tub2), and the rDNA-ITS region, were amplified and sequenced. Of the 70 Fusarium strains, 70 % were identified as F. proliferatum that were recovered from six regions across Saudi Arabia. Fusarium solani (13 %), as well as one strain each of the following species: F. brachygibbosum, F. oxysporum, and F. verticillioides were also recovered. In addition, five Fusarium-like strains were recognized as Sarocladium kiliense by DNA-based data. The preliminary in vitro pathogenicity results showed that F. proliferatum had the highest colonization abilities on date palm leaflets, followed by F. solani. Although F. oxysporum f. sp. albedinis is the most serious date palm pathogen, F. proliferatum and F. solani are becoming serious pathogens and efforts should be made to restrict and control them. In addition, the potential toxin risks of strains belonging to F. proliferatum should be evaluated. 相似文献
13.
B. J. Deverall I. M. Smith S. Makris 《European journal of plant pathology / European Foundation for Plant Pathology》1968,74(1):137-148
Droplets of spore suspensions of each of four isolates ofBotrytis cinerea but not those of each of four isolates ofB. fabae proved to contain an antifungal compound 24 h after application on pod tissue ofVicia faba. Partial inhibition of germ-tube growth of three highly pathogenic isolates ofB. fabae was caused at 2.5 times the concentration of inhibitor needed to cause similar inhibition of each isolate ofB. cinerea and a weakly pathogenic isolate ofB. fabae. After extraction, concentration and chromatographic separation, 5–10 times more inhibitor was obtained from lesions in pods caused byB. cinerea than from those caused byB. fabae. However, the amounts of inhibitor extracted from whole leaves bearing either large lesions caused byB. fabae or small lesions caused byB. cinerea were almost the same. It is suggested that infection by either fungus induces inhibitor formation, but thatB. fabae metabolizes the inhibitor to an inactive form.No relation was found between amounts of an inhibitor produced in droplets of spore suspensions 24 h after application on pods of differential varieties ofPhaseolus vulgaris and the disease reactions caused by races ofColletotrichum lindemuthianum. Each race appeared to have a similar sensitivity to the inhibitor. Anatomical studies showed that only superficial growth of germ-tubes occurred in seed cavities in the first two days, after which penetration took place. Resistant or susceptible reactions were distinguished after 6 days in young pods, and even later in old pods. Before rejecting the hypothesis that the inhibitor may have a role in the mechanism of disease resistance, amounts of inhibitor in and around infection sites on leaves or stems should be measured. Apparent protection of leaf areas against infection was caused by prior inoculation with a race which was avirulent on the leaf. This phenomenon is consistent with the action of an inhibitor of the type found in pod tissues, but could be caused by reactions as yet unknown. 相似文献
14.
Takuya Hasegawa Atsushi Okabe Yusuke Kato Atsushi Ooshiro Hiroshi Kawaide Masahiro Natsume 《Journal of General Plant Pathology》2018,84(1):20-26
Tomato root exudates were analyzed using a bioassay to detect the chemoattractant for Ralstonia solanacearum. An activated charcoal-adsorbed fraction of root exudates from tomato cultivar Oogata-fukuju had chemoattractant activity for R. solanacearum strain MAFF 730138. The active component, purified using a Sep-Pak C18 cartridge, an activated charcoal column, diol-modified silica gel, and NH2-modified silica gel, is a new hydrophobic attractant. The final purified fraction produced a single peak in a diol-modified silica gel HPLC analysis. 相似文献
15.
Kai Jian Lei Li Zhang Xiao Yu Du Yi An Gai Hong Chang Guo Yong An 《European journal of plant pathology / European Foundation for Plant Pathology》2018,152(3):769-781
Verticillium wilt is a devastating disease caused by the soil-borne fungus Verticillium dahliae that causes severe wilt symptoms in more than 400 plant species, including economically important cotton. However, the molecular mechanism of plant resistance to Verticillium remains unclear. In this study, we identified an Arabidopsis mutant, vsad1 (verticillium sensitive and anthocyanin deficient 1), which showed more serious disease symptoms such as discoloration and chlorosis than wild-type Arabidopsis. vsad1 is a previously identified allele of the transparent testa 4 gene (tt4), which encodes chalcone synthase (CHS), a key enzyme involved in the biosynthesis of flavonoids. Our results showed that VSAD1 expression was induced in response to Verticillium dahliae infection. Overexpression of VSAD1 partially recovered the anthocyanin accumulation phenotype of the vsad1–1 mutant. The concentration of V. dahliae increased and ROS accumulation decreased in the vsad1 mutant after infection with V. dahliae. Knockdown of the homologous gene GhCHS in cotton plants increased their susceptibility to V. dahliae infection. Thus, we conclude that VSAD1 is involved in the regulation of plant resistance to Verticillium wilt. 相似文献
16.
The Rhizoctonia solani species consists of multinucleate isolates that belong to anastomosis groups AG1–AG3 and differ in virulence and host affinity. R. cerealis is a binucleate species of anastomosis group AG-D which causes sharp eyespot, a common plant disease in Poland. Rhizoctonia spp. is a ubiquitous soil pathogen that poses a significant threat for global crop production due to the absence of effective crop protection products. The aim of this study was to determine the virulence of R. solani and R. cerealis isolates towards Beta vulgaris, Zea mays, Triticum spelta and T. aestivum seedlings, to confirm the presence of endopolygalacturonase genes pg1 and pg5 in the genomes of the tested isolates and to evaluate the tested isolates’ sensitivity to triazole, strobilurin, imidazole and carboxamide fungicides. All tested isolates infected B. vulgaris seedlings. but none of them were virulent against Z. mays plants. R. solani isolates AG4 PL and AG2-2IIIB PL were characterized by the highest virulence (average infestation score of 2.37 and 2.53 points on a scale of 0–3 points) against sugar beet seedlings. The prevalence of infections caused by most of the analysed isolates (in particular R. solani AG4 J—11.8, and R. cerealis RC2—0.78) was higher in spelt than in bread wheat. The virulence of the analysed isolates was not correlated with the presence of pg1 and pg5 genes. The efficacy of the tested fungicides in controlling Rhizoctonia spp. infections was estimated at 100% (propiconazole + cyproconazole), 98.8% (penthiopyrad), 95.4% (tebuconazole) and 78.3% (azoxystrobin). 相似文献
17.
Eliana Wassermann Marcela Susana Montecchia Olga Susana Correa Vega Damián Ana María Romero 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(1):35-44
Tomato leaves showing severe leaf spot symptoms have been observed and sampled in the central west and southwest Taiwan during 2015 and 2016. The symptoms were similar to those of bacterial leaf spot/late blight diseases, but only Stemphylium-like fungi were consistently isolated from the diseased tomato. Upon spray inoculation of tomato, Stemphylium-like isolates caused leaf spot symptoms identical to those of naturally infected plants, and the pathogenic isolates were successfully re-isolated from inoculated leaves. The tomato-pathogenic isolates were identified as S. lycopersici based on morphological characterization and molecular identification. S. lycopersici has been previously reported to cause gray leaf spot of tomato in the temperate regions, but the majority of S. lycopersici-caused lesions were black/dark brown rather than gray in our surveillance. Accordingly, it is suggested that S. lycopersici-caused disease of tomato is named Stemphylium leaf spot of tomato more appropriately than tomato gray leaf spot. Moreover, S. lycopersici-caused leaf spot disease on tomato has been distributed in major tomato production regions in Taiwan. The information provided by our study will be important for future breeding of tomato cultivars, especially for tomato producers in Taiwan. 相似文献
18.
Rutin promoted resistance of tomato against <Emphasis Type="Italic">Xanthomonas perforans</Emphasis>
Ali Safaie Farahani S. Mohsen Taghavi 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(2):527-531
Xanthomonas perforans is the causal agent of bacterial spot, one of the most devastating diseases of tomato that results in considerable yield losses worldwide. Rutin, as a polyphenolic substance, was used to induce resistance in tomato against X. perforans. Rutin at concentration of 2 mM had ability to reduce the disease severity of bacterial spot. On the other hand, 2 mM rutin had no antibacterial activity in vitro. Expression profiling of pathogenesis-related gene 5 (PR-5), Phenylalanine ammonia-lyase (PAL) and lipoxygenase (LOX) was probed during the enhanced resistance by rutin. Pretreatment with rutin (rutin/ X. perforans) led to induction of PR-5, PAL and LOX compared to controls (water/ X. perforans). Our results suggest that rutin-induced resistance against X. perforans in tomato might be mediated through stimulation of some defense genes such as PR-5, PAL and LOX. 相似文献
19.
Q. Liu G. A. Beattie E. Saalau Rojas Mark L. Gleason 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(3):803-810
Cucurbit bacterial wilt, caused by Erwinia tracheiphila, is a devastating disease of cucurbit crops in the Midwest and Northeast U.S. Current management of bacterial wilt relies primarily on insecticide applications to control striped and spotted cucumber beetles (Acalymma vittatum and Diabrotica undecimpunctata howardi, respectively), which vector E. tracheiphila. Development of alternative management strategies is constrained by a lack of understanding of bacterial wilt etiology. The impact of host age on rate on symptom development and extent of bacterial movement in the xylem of muskmelon (Cucumis melo cv. Athena) was evaluated following wound inoculation of 2- to 8-week-old plants in growth chamber experiments. Wilting occurred more rapidly in plants after inoculating E. tracheiphila into 2- or 4-week-old plants than 6- or 8-week-old plants. Recovery of viable cells from stem segments revealed that vascular spread of E. tracheiphila was more extensive below than above the inoculation point. These findings provide experimental evidence that host age impacts the rate of symptom development in cucurbit bacterial wilt and that movement of the xylem-inhabiting pathogen E. tracheiphila within muskmelon plants occurs primarily in the downward direction. 相似文献
20.
Amal Smaili Abdelhakim Laachir Lalla Aicha Rifai Tayeb Koussa Fouad Bentiss Salaheddine Guesmi Mohamed Faize 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(4):1035-1048
Three isomers of the ligand 2,5-bis(pyridinyl)-1,3,4-thiadiazole, with the N atom of pyridine group in position 2, 3 or 4, named respectively, L2, L3 and L4 were compared for their use as plant defense activators. They were examined for their ability to protect tomato plants from Verticillium dahliae and Agrobacterium tumefaciens in the greenhouse, to induce reactive oxygen species and to activate plant defenses, including antioxidant enzymes. The three ligand isomers exhibited in vitro only slight inhibition of radial growth of V. dahliae, while no significant inhibition was observed for phytopathogenic bacteria. In the greenhouse, the three ligand isomers statistically reduced the severity of Verticillium wilt and crown gall on tomato plants, and the isomers L3 and L4 were the most efficient to control Verticillium wilt. This superiority was reflected in their differential ability to activate H2O2 accumulation, antioxidant enzymes including catalase and ascorbate peroxidase and other defense-related enzymes such as guaiacol peroxidase and polyphenol oxidase. These results demonstrated that the presence of the N atom within the two pyridinyl groups in the position 3 or 4 highly enhanced the activity of plant defense and antioxidant responses as well as their ability to reduce the severity of symptoms caused by V. dahliae on tomato. 相似文献