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1.
Bacterial wilt is a serious problem affecting many important food crops. Recent studies have indicated that treatment with biotic or abiotic stress factors may increase the resistance of plants to bacterial infection. This study investigated the effects of magnesium oxide nanoparticles (MgO NP) on disease resistance in tomato plants against Ralstonia solanacearum, as well as its antibacterial activity. The roots of tomato seedlings were inoculated with R. solanacearum and then immediately treated with MgO NP; the treated plants showed very little inhibition of bacterial wilt. In contrast, when roots were drenched with a MgO NP suspension prior to inoculation with the pathogen, the incidence of disease was significantly reduced. Rapid generation of reactive oxygen species such as O2?˙ radicals was observed in tomato roots treated with MgO NP. Further O2?˙ was rapidly generated when tomato plant extracts or polyphenols were added to the MgO NP suspension, suggesting that the generation of O2?˙ in tomato roots might be due to a reaction between MgO NP and polyphenols present in the roots. Salicylic acid‐inducible PR1, jasmonic acid‐inducible LoxA, ethylene‐inducible Osm, and systemic resistance‐related GluA were up‐regulated in both the roots and hypocotyls of tomato plants after treatment of the plant roots with MgO NP. Histochemical analyses showed that β‐1,3‐glucanase and tyloses accumulated in the xylem and apoplast of pith tissues of the hypocotyls after MgO NP treatment. These results indicate that MgO NP induces systemic resistance in tomato plants against R. solanacearum.  相似文献   

2.
In order to investigate the effects of flagellin secreted by bacteria associated with pine wood nematode (Bursaphelenchus xylophilus) on pine cells, suspension cells of Pinus thunbergii were treated with flagellin of Pseudomonas fluorescens GcM5-1A, and some physiological indices were determined. Superoxide anions radical (·O2 ?) in treated suspension cells increased with prolongation of treatment time, with maximum content of 1,282 μmol g?1 FW at 30 h, but the content of H2O2 gradually decreased as compared with that in the control group. Maximum content of malondialdehyde (MDA) and free proline, which is 1.72 times and 1.49 times of that in the control, respectively, appeared when suspension cells were treated for 12 h, after that both of the contents decreased gradually. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalases (CAT) also increased at the primary stage of treatment and then decreased compared with those of the control.  相似文献   

3.
In this study, we investigated the ability of DL-3-aminobutyric acid (BABA) to protect tomato against bacterial wilt caused by Ralstonia solanacearum. This was combined with studies of accumulation of total phenolic compounds, free and total salicylic acid (SA), and activity of enzymes related to plant defence, i.e., polyphenol oxidase (PPO) and catalase (CAT). Under greenhouse conditions, tomato plants pre-treated by soil drenching with BABA profoundly reduced disease severity of bacterial wilt compared to plants receiving a soil drench with water. Thus, BABA reduced leaf wilting index by 75.3 % and vascular browning index by 69.9 %, without any in vitro inhibitory activity on the pathogen. BABA treatment significantly reduced the population of R. solanacearum in stems of tomato plants and additionally also significantly increased both fresh and dry weight of roots and shoots of tomato plants compared with the inoculated control. Application of BABA resulted in a high increase in PPO activity both in plants with and without inoculation. Compared to water-treated plants, treatment with BABA also induced a significant increase of total phenolic compounds as well as of free and total SA in leaves of both inoculated and non-inoculated tomato plants at all sampling times. CAT activity decreased in tomato plants treated with BABA in comparison with the water-treated control plants and the decrease in activity correlated with an increasing total SA accumulation. These findings suggest that BABA treatment resulted in induction of resistance to bacterial wilt in tomato.  相似文献   

4.
The effects of riboflavin (vitamin B2) against Alternaria rot caused by Alternaria alternata and its possible mechanism in harvested Zaosu pear fruit were investigated. Riboflavin at a concentration of 1.0?mM effectively inhibited development of Alternaria rot and enhanced the activities of defense-related enzymes, such as phenylalanine ammonia-lyase (PAL), polyphenoloxidase (PPO) and peroxidase (POD), and increased accumulation of flavonoids, phenolics and lignin. Riboflavin also affected reactive oxygen metabolism of pear fruit by increasing O 2 ?C production and H2O2 content, and enhancing the activities of the main detoxifying enzymes, such as catalase (CAT) and superoxide dismutase (SOD). Spore germination and mycelial growth of A. alternata were inhibited by riboflavin and the inhibitory effect was highly correlated with the riboflavin concentration used in this study. It is suggested that the effects of riboflavin on Alternaria rot in pear fruit may be associated with its direct fungitoxic property against the pathogens, and the elicitation of biochemical defense responses in the fruit.  相似文献   

5.
Bacterial wilt caused by Ralstonia solanacearum is one of the most devastating bacterial diseases of plants worldwide. Management of bacterial wilt in tomato and other crops has been difficult, and so novel but easily implemented control methods are being sought. To evaluate the effect of cold-water irrigation on bacterial wilt of tomato, four treatments were used in which CF (chemically fertilized) soil and CF + FYM (chemical fertilizer + farmyard manure [FYM]) soil were inoculated with a bacterial suspension (R. solanacearum strain YU1Rif43) at 106 colony forming units (CFU) g?1 soil. Tomato seedlings were grown in Agri-pots in a plant growth chamber. The soil was irrigated with water that was kept at the same temperature in each treatment: 4, 10, 20, or 30°C. Incidence and severity of wilt, counting of the colonies of the culturable population of pathogen, and dry-mass and height of the plants were examined. After 45 days and in both kinds of soil, most of the plants had wilted in soil irrigated at 30°C. Wilt incidence was substantially reduced when transplanted seedlings were irrigated at lower temperatures (4–20°C). Survival of R. solanacearum was also reduced after being irrigated with water at lower temperatures, indicating that the reduced incidence of wilt was linked to reduced survival of the pathogen. Dry-mass and plant height were slightly higher under control conditions than in soils irrigated at lower temperatures. This study suggests that cold-water irrigation could significantly reduce bacterial wilt of tomato and have an adverse effect on survival of the wilt pathogen.  相似文献   

6.
Ralstonia solanacearum, the causal agent of bacterial wilt of tomato, grows in infected plants and migrates from the roots into the soil. We investigated the effectiveness of bacterial wilt-resistant tomato rootstock in reducing the migration of R. solanacearum from susceptible scions into the soil. Rootstock stems were either 3–5 cm tall (low-grafted, LG) or ≥?10 cm tall (high-grafted, HG). After inoculation of scions of the susceptible cultivar (SC) with R. solanacearum below the first flower, there was no difference in disease progression among LG, HG, and ungrafted SC plants, and plants had wilted by 2 weeks. However, the rate of detection of R. solanacearum in the soil of wilted plants was reduced by grafting. The size of the R. solanacearum population in the soil of fully wilted plants increased in the order of HG?<?LG?<?SC. These results show that grafting onto resistant rootstock strongly suppressed the migration of R. solanacearum into the soil by the time of full wilting, and the effect was stronger with a longer rootstock. Migration of R. solanacearum into soil increased with increasing disease severity in SC, LG and HG. These facts suggest that early uprooting of slightly infected plants could control the spread of the bacteria into the soil.  相似文献   

7.
Soft rot of Chinese cabbage is a disease of great economic importance to the State of Pernambuco, Brazil. The present study aimed to evaluate the effect of two calcium sources in different concentrations (calcium nitrate [Ca(NO3)2] at 0, 0.15 and 0.3 g l?1 and calcium chloride (CaCl2) at 0, 1 and 5 g l?1) that were applied through two methods (leaf spraying and soil drenching) on the control of soft rot. Further, it aimed to analyze calcium absorption by the plant and to determine calcium’s role in leaf and cell structure using microscopy. Ca(NO3)2 applied by both methods was effective in controlling soft rot caused by Pectobacterium carotovorum subsp. carotovorum, as it reduced the disease by up to 48.5 % when sprayed onto the leaves (0.15 g l?1). A significant increase in the leaf calcium content was observed only in the plants that were sprayed with higher doses of Ca(NO3)2 and CaCl2. In all of the calcium treatments, light microscopy analyses revealed an increased number of chloroplasts and improved structuring of the palisade parenchyma, while transmission electron microscopy analyses revealed an increased cell wall thickness that was especially evident for the 0.15 g l?1 Ca(NO3)2 treatment applied by leaf spraying and soil drenching.  相似文献   

8.
以番茄品种鑫语为试验材料,在开花盛果期喷施含Ca(NO_3)_2、Ca(H_2PO_4)_2、KSiO_4、Ca(NO_3)_2+KSiO_4及Ca(H_2PO_4)_2+KSiO_4的悬液,探讨钙硅单一及配合施用对设施春茬番茄根系生长、NPK吸收、产量及水分利用率的影响。结果表明:喷施钙硅悬液显著促进番茄根系生长及发育,显著促进根系和果实磷钾吸收;含钙悬液单独喷施处理的根系和果实氮吸收显著高于硅悬液及钙硅复配悬液;两种含钙悬液Ca(NO_3)_2和Ca(H_2PO_4)_2喷施处理取得最佳调控效果,与对照相比,分别使番茄增产9%和7%,水分利用率提升7、5.5 kg·m~(-3),喷施Ca(NO_3)_2+KSiO_4使番茄增产4.7%,水分利用率提升3.8 kg·m~(-3),喷施Ca(H_2PO_4)_2+KSiO_4和KSiO_4未取得显著的调控效果;含钙悬液单独喷施处理增加番茄产量与其促进根系发育及增加植株N吸收密切相关;两种含钙物质与KSiO_4对番茄产量的影响存在显著的交互效应,对产量的贡献呈:含钙物质含钙物质×KSiO_4KSiO_4。含钙悬液喷施技术简单高效,能实现番茄增产及生物节水能力提升。  相似文献   

9.
An oxidative burst was previously demonstrated to be induced in tomato plants by race specific elicitors of the fungal pathogen Cladosporium fulvum . The in planta levels of H2O2estimated to occur during elicitor treatment, were compared with the levels required to show toxicity to host cells and to the fungal pathogen. Injection of Cf-9 tomato leaves with 100 m m H2O2caused an insignificant degree of necrosis and 1m H2O2was required to cause complete leaf necrosis comparable to that induced by the AVR9 elicitor. Assays with Cf-5 tomato cell suspensions confirmed the low toxicity of H2O2to tomato cells but, as expected, the addition of Fe2+with H2O2(or with intercellular fluids containing AVR5 elicitor) enhanced cell death as determined by the Evans Blue assay. Germination and germ tube growth of conidia of C. fulvum were significantly retarded by 4–5 m m H2O2, and at higher concentrations, death of germ tubes was observed (ED50=22 m m), as determined by the fluorescein diacetate assay. The addition of Fe2+with H2O2had little effect on fungal growth or viability in vitro . These results suggest that the amount of H2O2accumulating during an elicitor-induced response in leaves may be sufficient to affect fungal colonization but not to affect viability of host cells unless the Fe2+status in the apoplast is in some way altered by the elicitor to facilitate OH.production via the Fenton reaction.  相似文献   

10.
Helicoverpa armigera is the most serious insect pest in chickpea that causes significant yield losses due to its feeding on vegetative (leaves) and reproductive (developing pods and seeds) parts of plants. The present aim of study was to explore response dynamics of induced defence mechanism in leaves, podwall and seeds of ten chickpea genotypes (ICC 506, ICCV 10, ICC 10393, 5283, RSG 963, GL 25016, GL 26054, ICCL 86111, ICC 3137, L 550) after insect infestation. Two chickpea genotypes namely ICC 3137 and L 550 were found to be highly susceptible to Helicoverpa armigera infestation due to higher leaf and pod damage in them as compared to rest of eight genotypes which are found to be considerably resistant due to lower damage. Insect infestation induced decreased activities of defensive enzymes such as peroxidase (POD), catalase (CAT), glutatione reductase (GR) and polyphenol oxidase (PPO), decreased free radical scavenging activities in terms of 2,2-diphenyl-1-picryl hydrazyl (DPPH), decreased contents of signaling molecules such as nitric oxide ((NO), hydrogen peroxide (H2O2), reduced content of insect feeding behaviour regulating molecules such as total phenols, trypsin inhibitor and accumulation of membrane damage marker such as malondialdehyde (MDA) in leaves of ICC 3137 and L 550; decreased POD activity, nitric oxide content and H2O2 in podwall of L550; decreased SOD, GR, nitric oxide content and H2O2 in seeds of L550 resulted in aggravation of infestation induced oxidative stress and makes these genotypes more vulnerable to insect damage. The resistance of rest eight chickpea genotypes to insect infestation was due to the integrative effect of up regulated defensive components in leaves, podwall and seeds such as enhanced activities of CAT, POD, GR, PPO and PAL along with accumulation of H2O2` and total phenols in leaves, increased SOD, POD, GR and PPO activities along with increased contents of trypsin inhibitor and total phenols in podwall; increased SOD, GR, PPO activities and accumulated total phenols in seeds of resistant chickpea genotypes might be responsible for causing significant shift in oxidative status of these genotypes due to scavenging of free radicals, maintenance of membrane integrity and deterrent to insect feeding. Induced glycine betaine after herbivory was found to be positively correlated with superoxide dismutase and trypsin inhibitors. H2O2 content was positively correlated with trypsin inhibitor, DPPH, ferric reducing antioxidant power (FRAP) and total phenols in leaves and with FRAP, DPPH and total phenols in pod wall indicating that H2O2 might be stimulating the cascade that will be helping to scavenge free radical species and correlation with phenols and trypsin inhibitor indicated that it act as toxicant to insect feeding.  相似文献   

11.
Fungi infection in fruits is an important factor in postharvest losses. The effect of a treatment with a fungal elicitor on the response of tomato fruit to Fusarium oxysporum infection and changes in the phenylpropanoid metabolic pathway was studied. Fungal elicitor retarded for 3 days the development of the Fusarium rot development in tomato, at concentration of 2 g?l ?1 (B2-F treatment). This treatment also induced a 3.11- and 6.03-fold increase of caffeic and chlorogenic acids, respectively, as compared with the control. Furthermore, the flavonoids naringenin-7-O-glucoside, rutin and kaempferol-3-O-glucoside, showed a greater abundance in tomato under the B2-F treatment after 6 days at 20°C. It is concluded that the fungal elicitor reduced the development of Fusarium rot by inducing the biosynthesis of metabolites from the phenylpropanoid metabolic pathway which forms part of the defense response in tomato fruit.  相似文献   

12.
为明确硫化氢对盐胁迫下加工番茄种子萌发的缓解作用,用Na Cl半致死浓度为85 mmol·L~(-1)的KT-63(耐盐性弱)和半致死浓度为120 mmol·L~(-1)的KT-18(耐盐性强)为材料,用各自的半致死浓度与不同浓度的NaHS(0.2,0.4,0.6,1.0 mmol·L~(-1))分别配成混合液处理种子。结果表明,随着NaHS浓度的增加,种子的发芽率、发芽势、发芽指数、活力指数、SOD、POD、CAT活性呈先上升后下降的趋势,其中与盐胁迫单独处理相比,用0.4mmol·L~(-1)NaHS处理,种子的发芽率、发芽势、发芽指数、活力指数、SOD、POD、CAT活性在KT-63中分别提升70%、250%、120%、130%、6.7%、150%和180%,在KT-18中分别提升50%、250%、60%、80%、4.3%、160%和200%,而MDA的含量显著降低,并且对KT-63的缓解效应强于KT-18。综上所述,H2S(0.4 mmol·L~(-1))有效缓解了加工番茄萌发过程中盐胁迫的抑制作用,促进了种子的萌发。  相似文献   

13.
Recent evidence suggests that nitric oxide (NO) signaling plays an important role in plant–pathogen interactions and that aconitase is a major target of NO. In the present study on the signaling role of NO in the elicitation of defense responses in peach fruit against Monilinia fructicola and subsequent effect on brown rot disease, 15 μM NO solution induced disease resistance in harvested peaches. As a potentiated elicitor, NO induced high levels of endogenous NO and superoxide (O2 ?), hydrogen peroxide (H2O2), and NADPH oxidase and Ca2+-ATPase activity in the fruit. Aconitase activity in peach fruit was inhibited by NO. Activity of partially purified aconitase was inhibited in vitro by sodium nitroprusside (SNP) and H2O2; however, the inhibition could be relieved by carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (cPTIO) or catalase (CAT), indicating that the defense response and signals induced by NO transduction depend on aconitase and conditions leading to elevated levels of NO; otherwise, H2O2 would inactivate aconitase directly in fruit. Treatment with NO resulted in salicylic acid (SA) accumulating during storage. Higher levels of jasmonic acid (JA) were detected in NO-treated fruit 48 h after the treatment. But after NO was removed, the level of SA and JA were lower than in the control. The results suggest that exogenous NO enhances resistance of harvested peach fruit against the fungus by inducing signals such as endogenous NO, reactive oxygen species (ROS), SA and JA and by inhibiting aconitase activity.  相似文献   

14.
Ralstonia solanacearum causes bacterial wilt disease in many plant species, including mulberry. Here, we used a suppression subtractive hybridization (SSH) approach to identify specific DNA fragments in R. solanacearum race 5-biovar 5. The genome of the R. solanacearum M7 strain was subtracted from that of the GMI1000 strain, resulting in the identification of 85 subtracted fragments. The primer set MG67-F/R for identification of Ralstonia solanacearum race 5-biovar 5 strains was designed on the basis of the clone MG67 sequence. Furthermore, a multiplex PCR was developed by using the primer set MG67-F/MG67R in combination with the species-specific primer pair 759/760. A 156 bp r5-bv5-specific fragment, together with a 282 bp species-specific fragment, was amplified from all tested R. solanacearum r5-bv5 strains. The sensitivity of the multiplex PCR made it possible to detect concentrations as low as 102 CFU ml?1 of pure culture. Moreover, the r5-bv5-specific multiplex PCR was successfully applied to detect Ralstonia solanacearum race 5-biovar 5 strains in diseased mulberry samples. Therefore, the multiplex PCR assay can be used as a reliable diagnostic technique to enable researchers to rapidly identify isolates of R. solanacearum race 5-biovar 5.  相似文献   

15.
Spray solutions containing 0.3% Ca which were prepared from four different calcium sources were foliar-sprayed on greenhouse-grown tomato plants, infected with theTomato mosaic virus Tobamovirus (ToMV) or not. ToMV-infected and uninfected control groups were sprayed with distilled water. Growth and macronutrient (N, P, K, Ca and Mg) composition of tomato plants as well as virus concentration and its relative infectivity were investigated in treated and untreated plants. The Ca sprays were applied three times: on the same day as inoculation, and 15 and 30 days after inoculation. Virus concentration in tomato plants generally decreased with foliar-sprayed Ca. Virus concentration (DAS-ELISA absorbance) was reduced by foliar-sprayed Ca, but plants remained infected. At the same time, tissue Ca concentrations increased significantly with foliar-applied Ca, with the exception of CaNO3·4H2O+0.05M Na-EDTA. ToMV reduced the fresh and dry weights and Ca concentrations of tomato plants, but significantly raised P concentration in the tissue. Neither virus inoculation nor foliar Ca applications affected N and Mg concentrations in tomato plants. The foliar-applied Ca from all the sources gave K concentrations similar to those of control plants. http://www.phytoparasitica.org posting Jan. 26, 2007.  相似文献   

16.
以酿酒葡萄"赤霞殊"(Cabernet Sauvignon,CS)1年生扦插苗为试材,采用营养液水培系统,研究了根施外源硅(K2SiO3·9H2O,Si)对盐(50 mmol/L NaCl)胁迫下赤霞珠葡萄幼苗叶片生理生化特性的影响.结果表明:盐胁迫处理下,葡萄幼苗叶片超氧阴离子(O2-')产生速率加快,过氧化氢(H2O2)、丙二醛(MDA)含量和相对膜透性增加;超氧化物歧化酶(SOD),过氧化物酶(POD)和过氧化氢酶(CAT)活性增强;组织含水量降低;施用2.0mmol/L Si明显抑制了O2-、H2O2和MDA的积累,增加了组织含水量,并进一步提高了抗氧化酶SOD和POD的活性.说明外源Si可通过提高盐胁迫下葡萄幼苗体内的抗氧化酶活性,从而降低活性氧(ROS)水平,一定程度上减轻盐胁迫对植株所造成的细胞膜脂过氧化伤害,增强其耐盐性.  相似文献   

17.
Bacterial canker is an economically important disease of tomato. Resistance induced by DL-β-Amino butyric acid against bacterial canker caused by Clavibacter michiganensis ssp. michiganensis in tomato plants was investigated. Different doses of DL-β-Amino butyric acid (250–1000 μg ml−1 doses) were tested on 3-week old plants inoculated with a 108 CFU ml−1 bacterial suspension, and disease development was evaluated after inoculation and treatment. Although in vitro growth of the bacteria was not affected by DL-β-Amino butyric acid treatment, foliage sprays of 500 μg ml−1 DL-β-Amino butyric acid significantly suppressed disease development up to 54% by day 14 after inoculation at the four different doses tested. Bacterial populations were reduced by 84% in BABA-treated plants compared to water-treated plants by day 4 after inoculation. Inoculated BABA-treated plants showed significantly higher phenylalanine ammonia-lyase activity, peroxidase activity, and H2O2 concentration than inoculated water-treated plants during day 1 after treatment. These findings suggest that the DL-β-Amino butyric acid treatment resulted in an increase of these enzymes and in H2O2 concentration in planta, and was associated with induction of resistance to bacterial canker.  相似文献   

18.
A spotted-leaf mutant Y181, produced by 60Coγ-radiation treatment of Zixuan1, was identified in rice. The result of TEM demonstrated the number of starch grains decreased significantly, the distribution and volumes of osmiophilic granules and lipid balls were larger in the leaf cells around the lesion mimics, the chloroplasts in mesophyll cells disappeared and just leaving a few rupture thylakoid membranes in the cytoplasm and some transmutative starch granules in Y181. Compared with the wild type, the content of chlorophyll was decreased significantly, while the H2O2 content, and SOD, POD and CAT activity were obviously increased in mutant. DAB staining and H2O2 treatment further revealed oxidative burst in spotted leaves. Expression of lesion-related gene showed RuBisCo-L, RuBisCo-S, PDI and TPX was down-regulated, while PBZ1 was up-regulated in the leaf cell at the lesion mimics. Disease reaction to Magnaporthe grisea indicated that the resistance of Y181 was reduced. Genetic analysis showed that the mutant was controlled by a recessive nuclear gene, which was delimited to a 390 kb region between CH12-936 and RM7195.  相似文献   

19.
利用开顶式气室(OTC)研究了高浓度O3对春小麦叶片膜脂过氧化程度、活性氧含量、抗氧化系统的影响。结果表明,随着臭氧浓度的升高,不同生育时期小麦叶片的相对电导率、MDA含量显著上升(P<0.01);穗粒重明显下降(P<0.05);O2-.产生速率和H2O2含量显著增加(P<0.05)。SOD活性、CAT活性、POD活性随生育进程和O3浓度升高而显著下降。而对抗氧化物如类Car含量、ASA含量的影响不显著。臭氧浓度增加,促使小麦叶片膜的伤害,引发了膜脂过氧化作用,产生了过多的活性氧自由基,破坏了抗氧化系统功能,影响了叶片的正常生理代谢。  相似文献   

20.
Sodium hypochlorite (NaOCl) can release dormancy of imbibed wild oat (Avena fatua L.) seeds. Treatments found effective included (i) immersing intact seeds in 800 mm NaOCl for 1 h followed by incubation on 5 × 10?4m gibberellin A3(GA3); (ii) immersing dehulled seeds in 800 mm NaOCl for 1 min followed by incubation on 5 × 10?4m GA3; (iii) immersion of dehulled seeds in much lower concentrations of NaOCl, e.g. 13 4 mm for 3 h followed by incubation on water; or (iv) incubating dehulled seeds on a low concentration of NaOCl. Based on the concentrations of each of the reagents required to produce equivalent responses, NaOCl is approximately 4–6 times more effective than hydrogen peroxide (H2O2) in triggering the onset of germination, and 6 times as effective in causing growth inhibition in the roots. These results suggest the modes of action of NaOCl and H2O2 in the termination of dormancy reside in a modification of the properties of the hull and seed coat membranes, and in the provision of additional oxygen to the seed.  相似文献   

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