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1.
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2.
In tomato crop, the induction of resistance emerges as an important alternative for achieving the reduction of chemicals in disease control. This study aimed to evaluate the ability of 28 Trichoderma isolates to promote the growth of tomato seedlings and to induce systemic resistance (ISR) against Xanthomonas euvesicatoria and Alternaria solani, the causal agents of bacterial spot and early blight, respectively. Twelve isolates promoted the increase of plant dry matter mass (DMM) above 100%, showing the great potential of these strains. All isolates were able to colonize the root system of tomato plants. The plant growth-promoting isolates were further evaluated for potential elicitation of ISR. Treatment of the soil with all Trichoderma isolates provided protection in tomato plants from 24.13 to 95.94% against X. euvesicatoria and 30.69 to 95.23% against A. solani. The most efficient isolates in reducing the severity of bacterial spot and early blight were the isolates IB 28/07, IB 30/07, IB 37/01 and IB 28/07, IB 30/07 and IB 42/03, respectively. The effect of different time intervals between Trichoderma application and inoculation with pathogens in inducing systemic resistance in tomato plants was evaluated for the isolate IB 28/07. IB 28/07 conferred protection against both diseases at all time intervals, confirming the ability of the isolate to reduce the severity of these diseases up to 21 days after treatment of tomato plants. In vitro assays revealed that all isolates of Trichoderma were able to degrade cellulose. Only the isolate IB 34/08 showed antagonistic activity against X. euvesicatoria and none caused reduction in the in vitro mycelial growth of A. solani. Trichoderma isolates were identified at species level by DNA sequencing.  相似文献   

3.
The population dynamics of Xanthomonas campestris pv. vitians (Xcv) was studied both externally and internally in lettuce, tomato and pepper plants. In addition, the application of bactericides during transplant production period was carried out for the management of bacterial leaf spot of lettuce under greenhouse conditions. Epiphytic populations of Xcv were recovered on leaves of lettuce plants (105 CFU/g) 5 weeks after sprayed than the other plant species when inoculated with 108 CFU/ml of Xcv. When plants of each crop species infiltrated with the bacterium at 105 CFU/ml, the highest populations were developed in lettuce (108 CFU/cm2) followed by pepper with 106 CFU/cm2 and tomato with 105 CFU/cm2 10-days after infiltration. Application of a mixture of Maneb and Kocide or Kocide alone as a foliar spray on lettuce significantly reduced the incidence and disease severity of bacterial leaf spot by 29 and 27% respectively. Spread of the bacterium and development of the disease may partly be managed by avoiding intercropping of these plants commonly grown in close proximity to lettuce. For the management of leaf-associated populations of Xcv in lettuce, use of a mixture of Maneb and Kocide is advocated to minimize the effect of attacks.  相似文献   

4.
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5.
In 2009 and 2010, the effect of delayed planting on bacterial pustule (Xanthomonas axonopodis pv. glycines) and wildfire (Pseudomonas syringae pv. tabaci) in four soybean cultivars was evaluated in fields in Suwon and Naju, Korea. Soybean was planted on 15 May as the first (traditional) planting date; then, planting was delayed at approximately 15-day intervals (three times) after the first planting. In plots planted approximately 15 or 30 days after the traditional planting date, the disease incidence in highly (Saeolkong and Taegwangkong) and moderately (Pungsannamulkong) susceptible cultivars was significantly reduced under moderate disease pressure, but disease reduction in highly susceptible cultivars was sometimes diminished especially against bacterial pustule under high disease pressure. Altered planting date had no effect on disease incidence in the least susceptible (resistant) cultivar (Cheongja-3-ho), regardless of disease pressure. Consistent differences in disease occurrence were not observed between planting locations. The results from this study indicate that delayed soybean planting reduced the bacterial disease incidence and differentially affected resistant and susceptible cultivars. Thus, planting resistant cultivars at the optimal planting date is desirable, but in the case of susceptible cultivars, delayed planting could be considered along with application of other control measures such as agrochemicals.  相似文献   

6.
Common bacterial blight disease of cowpea, caused by Xanthomonas axonopodis pv phaseoli, has been identified as the most important biotic constraint to cowpea production worldwide. Continuous and indiscriminate application of chemical pesticides has necessitated the search for an environment friendly method of control. Azadirachta indica (neem), Acalypha wilkisiana (red acalypha) and Carica papaya (pawpaw) extracts were field-tested against common bacterial blight disease. The experiment was laid out as a randomized complete-block design (RCBD) with three replicates. Cold extracts of 6.67% concentration of the plant leaves were sprayed on cowpea (variety ‘Ife brown’) foliage. Streptomycin sulfate of 0.2% concentration was applied as a positive control and sterile distilled water as a negative control. Incidence of common bacterial blight ranged from 20.00 to 43.74% and severity from 1.02 to 2.00 on a 1–6 scale, where 1 = no symptoms of common bacterial blight and 6 = necrotic lesions on more than 75% of the leaf area. A combination of extracts of pawpaw, neem and red acalypha reduced disease incidence by 73.68% and improved yield by 1.58 tons/ha (a 73.49% increase) compared with untreated control. Azadirachta indica, Acalypha wilkisiana and Carica papaya extracts, both singly and in combination (Pawpaw + neem + Acalypha, Pawpaw + neem, Pawpaw + Acalypha and neem + Acalypha), reduced incidence and severity of common bacterial blight disease and increased yield of cowpea. Thus, these plant extracts could serve as viable alternative to synthetic chemicals to control Xanthomonas-caused diseases in cowpea.  相似文献   

7.
The resistance to bismerthiazol in the Xanthomonas oryzae pv. oryzae population in China has not been clearly determined. Three bismerthiazol-resistant mutants (1-1-1, 2-1-1, 4-1-1) of X. oryzae pv. oryzae were induced on rice plants and the characteristics were compared with their parental strain ZJ173. After 10 subcultures on fresh bismerthiazol-free nutrient agar plates and after being inoculation onto and re-isolation from untreated rice plants two times, the mutants remained pathogenicity on rice plants treated with 300 μg/ml bismerthiazol, indicating that the in vivo-induced bismerthiazol resistance was stable in vivo. The in vitro characteristics of the bismerthiazol-resistant mutants and a wild-type bismerthiazol-sensitive strain (ZJ173) were also compared. The three mutants grew faster than ZJ173 during the logarithmic growth phase but at the same rate during the decline phase. Bismerthiazol had protective and curative activity against strain ZJ173 but not against the three mutants. To evaluate the current degree of bismerthiazol resistance in field populations of X. oryzae pv. oryzae in China, 781 isolates of X. oryzae pv. oryzae were obtained from 1419 leaf samples collected from Yunnan, Sichuan, Jiangsu, Anhui, Hubei, Guangdong, Hainan, and Hunan Provinces in China from 2007 to 2009. The in vivo sensitivity of 505 of the 781 isolates to bismerthiazol was determined by applying them to rice plants treated with 300 μg/ml bismerthiazol and evaluating blast severity. The tested strains were considered resistant, if they showed <70% inhibition relative to strain ZJ173. Of the 505 isolates, 62 were resistant to bismerthiazol. The resistance frequencies among field population ranged from 0 to 21.1%, differed among the provinces, and was 11.2, 20.0 and 10.4% in 2007, 2008 and 2009, respectively. Resistance determined in vivo was not related to resistance determined in vitro. The in vivo-induced bismerthiazol resistance identified in this study will serve as a base line for further studying bismerthiazol resistance in fields, and the current degree of bismerthiazol resistance in field populations of X. oryzae pv. oryzae in China determined would be useful for the rice growers for control of rice bacterial blight.  相似文献   

8.
Several bacterial strains were isolated from different rhizospheres. Among these, strain PDY7 exhibited strong antibacterial activity against the rice bacterial blight (BB) pathogen Xanthomonas oryzae pv. oryzae (Xoo) by the laboratory dual plate assays. The antibacterial property of the strain PDY7 was further investigated for the production of 2,4-diacetylphloroglucinol (DAPG), which amplified a characteristic of 629-bp DNA fragment by PCR-based screening method using phlD primers. The application of phlD positive strains was carefully evaluated for disease control and growth promotion of rice plants under field conditions. The selected strain PDY7 suppressed the rice BB by 58.83% and 51.88% under glass house and field conditions, respectively. In addition, the strain PDY7 showed significant two-fold increase in root length (18.08 cm), shoot length (29.81 cm), and grain yield (96.07 g). Strain PDY7 promoted the growth of rice plants by production of indole-3-acetic acid (IAA), which was determined by high performance liquid chromatography (HPLC) analysis. Our findings suggest that PDY7 belongs to the P. fluorescens group and can serve as potential biocontrol of BB as well as biofertilizer agent for growth promotion of rice.  相似文献   

9.
外源水杨酸对杂交稻幼苗抗白叶枯病的效应   总被引：2，自引：1，他引：1  
杂交水稻幼苗感染白叶枯病菌后,其叶片中ＳＯＤ和ＰＯＸ活性明显增强,ＭＤＡ含量和膜透性显著提高。经过一定浓度水杨酸（ＳＡ）浸种或３叶期幼苗根际预处理,ＳＯＤ和ＰＯＸ活性呈增长趋势,而膜脂过氧化作用受到不同程度的抑制。３叶期幼苗施用ＳＡ比浸种处理效果好。感病组合汕优６３的变化幅度大于抗病组合威优６号。可认为ＳＡ对杂交稻幼苗抗白叶枯病有一定效应。  相似文献   

10.
The antifungal activity of steam-exploded liquid waste (SELW) produced by the detoxification of steam-exploded biomass of Miscanthus sinensis, Arundo donax and wheat straw for 2nd generation industrial bioethanol production was studied against plant pathogenic fungi for the first time. Quantification of fermentation inhibitors (2-furaldehyde, 5-hydroxymethylfurfural, acetic and formic acid) was carried out by standard methods. Mycelial growth inhibition and conidial germination of eight fungal strains [Alternaria alternata, Botrytis cinerea, Colletotrichum acutatum, Cladosporium fulvum, Fusarium oxysporum f. sp. lycopersici (FOL), F. oxysporum f. sp. melonis (FOM), F. solani f. sp. pisi and Verticillium dahliae] were evaluated in vitro at different dilution rates (1:2, 1:4 and 1:8) for each SELW. Disease suppressiveness was assessed in vivo in eight horticultural pathosystems (A. alternata/tomato, B. cinerea/tomato, C. acutatum/strawberry, C. fulvum/tomato, FOL/tomato, FOM/melon, F. solani f. sp. pisi/pea and V. dahliae/eggplant) under greenhouse conditions. Pathogen suppression by each SELW, applied both in spray form on to tomato leaves and skins of tomato and strawberry, and by means of dipping method in watering suspensions on to seedling root systems of tomato, melon, pea and eggplant, was evaluated at dilution rates of 1:2, 1:4 and 1:8 using irrigation water during curative and preventive treatments. Investigations carried out in vitro showed that M. sinensis SELW was more suppressive than wheat straw SELW, and A. donax SELW was less suppressive than wheat straw SELW at the lowest dilution rates. Relationships between the concentration of 2-furaldehyde, acetic and formic acid present in SELWs and their antifungal effect were found. Moreover, B. cinerea, C. fulvum, V. dahliae, A. alternata, C. acutatum and F. solani f. sp. pisi were more effectively inhibited than FOL and FOM. Investigations performed in vivo showed that SELWs of M. sinensis and wheat straw can be diluted at a 1:2 rate and used for controlling six fungal diseases during preventive treatments. In particular, they can be used by dipping of the root systems during transplanting in the case of F. solani f. sp. pisi/pea and V. dahliae/eggplant; on the other hand, they can be nebulized on to the leaves and fruits before symptoms appearance in the case of A. alternata/tomato, B. cinerea/tomato, C. acutatum/strawberry and C. fulvum/tomato. This study is of particular interest because it points out how these SELWs could be employed in horticultural crop protection in Southern Italy, thereby making it possible to effectively combine industrial production of 2nd generation biofuels with sustainable horticulture under greenhouse conditions.  相似文献   

11.
Bacterial spot of tomato (Solanum lycopersicum) caused by Xanthomonas campestris pv. vesicatoria (Xcv) is a devastating disease of tomato world-wide. In the southeastern United States, high summer temperatures and humidity are ideal conditions for this disease, resulting in defoliation, fruit spotting and a significant reduction in fruit yield. Current organic production practices restrict the use of synthetic chemicals for disease control; hence, there is a need for the development of new and effective biopesticides to mitigate plant diseases. Among several biological agents with potential for disease control, Lentinula edodes (shiitake mushroom) has been shown to have antibacterial properties. A controlled-environment study was therefore conducted to validate L. edodes mycelia culture filtrate (Lemcf) foliar application to control bacterial spot of tomato using the cultivar Agriset 761. Lentinula edodes mycelia culture filtrate foliar spray significantly suppressed bacterial spot incidence in tomato foliage in vitro but was not effective in vivo. The phytotoxicity symptoms in Lemcf-treated tomato foliage were attributed to the presence of 422.78 μg of oxalic acid per milliliter of Lemcf (quantified by high-pressure liquid chromatography). Plant height and flowering were normal in Lemcf-treated plants. Additionally, Lemcf seed treatment did not adversely impact tomato germination but significantly enhanced the germination of marginal tomato seeds subjected to biotic stress (Xcv). Our results suggest that after eliminating oxalic acid from Lemcf, the product may be a potential biopesticide for managing bacterial spot of tomato. Future greenhouse or field experiments should be conducted after eliminating oxalic acid from L. edodes culture filtrates.  相似文献   

12.
Bacterial leaf spot of lettuce, induced by Xanthomonas campestris pv. vitians, constitutes a major disease on commercial lettuce (Lactuca sativa) production in south Florida. Under greenhouse conditions, resorcinol, two antioxidants, and various sugar alcohols such as mannitol, were evaluated alone, and in combination with Tanos® 50DF (25% a.i. of each component cymoxanil and famoxadone, E.I du Pont de Nemours and Company, Wilmington, DE) for control of bacterial leaf spot. Among the compounds evaluated, resorcinol (35–50% disease control) and mannitol (9–45%) were the most effective. In field trials, different mixtures containing propionic acid, mannitol, resorcinol, Tanos and or copper hydroxide (Kocide 3000®, 46.1%, 30% copper equivalent) were evaluated for the control of bacterial leaf spot of lettuce. Field data support a moderate impact of Tanos in disease reduction. Both greenhouse and field data support a synergistic interaction between Tanos and the compounds including copper, in disease reduction. The mixture Tanos + resorcinol, or copper/resorcinol, Tanos + copper provided better or similar disease control than copper alone. No phytotoxicity was observed in our trials. In an integrated management program for bacterial leaf spot of lettuce, Tanos may be useful in tank mixes with these compounds and copper.  相似文献   

13.
Bacterial leaf blight of rice (BLB), caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive diseases in Asian rice fields. A high-quality rice variety, LT2, was used as the recipient parent. IRBB21, which carries the Xa21 gene, was used as the donor parent. The resistance gene Xa21 was introduced into LT2 by marker-assisted backcrossing. Three Xoo races were used to inoculate the improved lines following the clipping method. Eleven BC3F3 lines carrying Xa21 were obtained based on molecular markers and agronomic performance. The 11 lines were then inoculated with the three Xoo races. All the 11 improved lines showed better resistance to BLB than the recipient parent LT2. Based on the level of resistance to BLB and their agronomic performance, five lines (BC3F3 5.1.5.1, BC3F3 5.1.5.12, BC3F3 8.5.6.44, BC3F3 9.5.4.1 and BC3F3 9.5.4.23) were selected as the most promising for commercial release. These improved lines could contribute to rice production in terms of food security.  相似文献   

14.
 研究了5个水稻品种邳早l5、蚌珠芒、南粳l5、中百4号和青华矮6号对3个水稻白叶枯病菌系的抗性遗传和抗性基因等位关系。这5个品种分别与感病品种沈农lO33杂交，对各组合的F1、F2和B1F1群体的抗性测试表明：邳早l5和蚌珠芒由一对显性基因控制其抗性。南粳l5和中百4号均由两对连锁的显性基因控制，交换值为30％。等位性测定表明，邳早15和蚌珠芒的一对显性基因与Xa-3等位，南粳l5和中百4号也均有一对显性基因与Xa-3等位；青华矮6号的一对不完全显性基因与Xa-3是等位的。  相似文献   

15.
《Plant Production Science》2013,16(2):133-138
Abstract

Localization of hydrogen peroxide (H2O2) accumulation during the interaction between rice and Xanthomonas oryzae pv. oryzae (X. oryzae pv. oryzae) was observed by histochemical analysis and electron microscopy. The changes that occurred in an avrXa7 mutantstrain of X. oryzae pv. oryzae including the decreased production of endogenous H2O2, impacted on the mean level of H2O2 accumulation during the interaction with the plant. The results of catalase and aminotriazole treatments indicated that the changes of H2O2 accumulation during the interaction are induced by the impairment of endogenous H2O2 accumulation in X. oryzae pv. oryzae. These results suggested that bacterial pathogen is a potential source of the H2O2 accumulated in the interaction between rice and X. oryzae pv. oryzae.  相似文献   

16.
This study was undertaken to determine the antibacterial efficacy of the leaves extracts of Lawsonia inermis in vitro and in vivo, against the phytopathogenic bacteria Pseudomonas savastanoi pv savastanoi IVIA 1628 and Agrobacterium tumefaciens. The hydroalcoholic extract of L. inermis was fractionated by liquid–liquid partition using hexane, chloroform, ethyl acetate and butanol. Among the tested fractions, the ethyl acetate (EtOAcF) and chloroform (CHCl3F) extracts exhibited high inhibition against all tested plant pathogens. The extracts exerted a bactericidal activity against both P. savastanoi and A. tumefaciens with MIC values ranging from 1.25 to 2.5 mg/ml. In planta experiments, the EtOAcF, tested at four concentrations (0.4, 0.2, 0.1 and 0.05 mg/wounds), completely inhibited the formation of knots on twigs of olive and tomato plants inoculated with pathogenic strains of P. savastanoi and A. tumefaciens (strains B6 and C58). The phytochemical screening revealed that the L. inermis fractions contain flavonoids, quinones, tannins and terpenoids. The qualitative analysis of the EtOAcF by LC–DAD–ELSD–ESI/MSn showed the presence of eight identified phenolic and phenolic glycoside compounds. These results suggest that L. inermis extracts could be used to control plant bacterial diseases caused by P. savastanoi and A. tumefaciens.  相似文献   

17.
This study presents the development of a PCR method for specific detection of Xanthomonas vesicatoria, causal agent of bacterial spot of tomato and pepper. Primer pair XV1F and XV1R was designed based on partial DNA sequence of the catalytic subunit of the ATP synthase gene atpD and tested using a collection of various bacterial pathogens mainly for tomato and pepper. After optimization of the PCR conditions, the 365 bp long fragment was only produced in X. vesicatoria samples. Therefore, the primers and protocol allow rapid and species-specific detection of X. vesicatoria.  相似文献   

18.
Xanthomonas oryzae pv. oryzae (Xoo) is a widespread pathogen causing bacterial leaf blight (BLB) disease, devastating rice productivity in many cultivated areas of Thailand. A specific and simple method for Xoo detection is required to improve surveillance of disease transmission and outbreak. This study developed a recombinase polymerase amplification (RPA) assay assisted with CRISPR-cas12a assay (RAC) for Xoo detection from bacterial cell suspension of infected rice samples without DNA extraction. The efficiency of the RAC system for Xoo detection using either Xoo80 or Xoo4009 locus was optimized to amplify and determine the sensitivity and specificity using a Xoo DNA template from bacterial cell suspension of infected rice samples without DNA extraction. The RAC system using the Xoo4009 locus gave a higher specificity than Xoo80 locus, because only Xoo species was amplified positive RPA product with fluorescence signal by cas12a digestion, which indicated no cross reactivity. Optimal RAC using the Xoo4009 locus enabled diagnosis of Xoo presence from both plant extracted samples of Xoo artificially inoculated rice leaves within 3 d post-inoculation without symptomatic BLB appearance, and Xoo naturally infected rice. Findings exhibited that RAC using the Xoo4009 locus offered sensitivity, specificity and simplicity for Xoo detection, with low intensities of Xoo-DNA (1 × 103 copies/μL) and Xoo-cell (2.5 × 103 cfu/mL). This developed RAC system showed significantly potential for Xoo detection at point-of-care application for early signs of BLB disease outbreak in rice fields.  相似文献   

19.
《Field Crops Research》2005,91(2-3):337-343
Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating diseases of rice in China. A strongly virulent Xoo strain, designated Z-173, is widely distributed across China and Southeast Asia. Indica rice DV85 is known to carry the two resistance genes, xa5 and Xa7. However, their effectiveness against Z-173 is unknown. Using a recombinant inbred line (RIL) population derived from a cross between DV85 and the susceptible cultivar Kinmaze, we have identified the quantitative trait loci (QTLs) responsible for the resistance of DV85 to Z-173. Following 2 years of phenotyping, three QTLs associated with the resistance were detected. These were linked to RFLP markers X362, X292 and G1091 on chromosomes 3, 5, and 6, respectively. Qxa-5 and Qxa-6 probably correspond to xa5 and Xa7, respectively. Both the xa5 and Xa7 resistances are stable over different years, and act independently of one another in determining resistance. The effect of xa5 was larger than that of Xa7. Efficient ways to improve the resistance to Z-173 are discussed.  相似文献   

20.
The production and productivity of rice has been challenged due to biotic and abiotic factors. Bacterial blight (BB) disease, caused by Xanthomonas oryzae pv. oryzae, is one of the important biotic stress factors, which reduces rice production by 20%–50%. The deployment of host plant resistance is the most preferred strategy for management of BB disease, and breeding disease resistant varieties remains a very economical and effective option. However, it is difficult to develop rice varieties with durable broad-spectrum resistance against BB using conventional approaches alone. Modern biotechnological tools, particularly the deployment of molecular markers, have facilitated the cloning, characterization and introgression of BB resistance genes into elite varieties. At least 46 BB resistance genes have been identified and mapped from diverse sources till date. Among these, 11 genes have been cloned and characterized. Marker-assisted breeding remains the most efficient approach to improve BB resistance by introducing two or more resistance genes into target varieties. Among the identified genes, xa5, xa13 and Xa21 are being widely used in marker-assisted breeding and more than 70 rice varieties or hybrid rice parental lines have been improved for their BB resistance alone or in combination with genes/QTLs conferring tolerance to other stress. We review the developments related to identification and utilization of various resistance genes to develop BB resistant rice varieties through marker-assisted breeding.  相似文献   

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