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1.
A species-specific PCR assay was developed for rapid and accurate detection of the pathogenic oomycete Phytophthora capsici in diseased plant tissues, soil and artificially infested irrigation water. Based on differences in internal transcribed spacer (ITS) sequences of Phytophthora spp. and other oomycetes, one pair of species-specific primers, PC-1/PC-2, was synthesized. After screening 15 isolates of P. capsici and 77 isolates from the Ascomycota, Basidiomycota, Deuteromycota and Oomycota, the PC-1/PC-2 primers amplified only a single PCR band of c . 560 bp from P. capsici . The detection sensitivity with primers PC-1/PC-2 was 1 pg genomic DNA (equivalent to half the genomic DNA of a single zoospore) per 25- µ L PCR reaction volume; traditional PCR could detect P. capsici in naturally infected plant tissues, diseased field soil and artificially inoculated irrigation water. Using ITS1/ITS4 as the first-round primers and PC-1/PC-2 in the second round, nested PCR procedures were developed, increasing detection sensitivity to 1 fg per 25- µ L reaction volume. The results suggested that the assay detected the pathogen more rapidly and accurately than standard isolation methods. The PCR-based methods developed here could simplify both plant disease diagnosis and pathogen monitoring, as well as guiding plant disease management.  相似文献   

2.
Aspartate transaminase and alanine transaminase levels showed considerable increase during initial (1 to 9 days) period of infection in all the experimental groups of mice and their level reached higher values than in the controls. The increase of enzymes was influenced by the degree of retention of worm load and the immunological damage caused by Ancylostoma caninum larvae within the host system.  相似文献   

3.
Aphidoletes aphidimyza is one of the most important predators used in the augmentative biological control of aphids, key pests of many crops worldwide. Adult females are very efficient in locating aphid infestations over a relatively long range, up to 45 m, and deposit eggs near or within aphid colonies. The predatory larvae are aphid generalists preying on several agriculturally important aphid species. The successful use of this biocontrol agent in agricultural systems depends on several biotic and abiotic factors. Among biotic factors, aphid species, plant structure, interspecific competition and intraguild predation may significantly impact the predator´s population dynamics. Key abiotic conditions include day lengths (above a critical threshold to prevent diapause), availability of mating sites in the crop, temperature (above 15 °C to enable egg laying), air relative humidity (above 70%) and availability of pupation sites. Although several successes have been reported in open field crops with naturally occurring or released populations, commercial releases are primarily used in protected crops. Optimized emergence boxes combining provisioning of food sources for the adults, integration with the technological advances that occurred in the greenhouse environment lately, insights into the nutritional ecology in open field crops and exploration of the genetic variability are proposed as future directions to improve adoption and efficacy of A. aphidimyza in crop protection. © 2018 Society of Chemical Industry  相似文献   

4.
烟草感染PVYN后叶脉坏死与总酚、类黄酮及PPO关系研究   总被引:2,自引:0,他引:2  
 本文采用常规摩擦接种和比色法研究了烟草感染PVYN后叶脉坏死与总酚、类黄酮及PPO的关系。试验结果表明:感病品种K326接种PVYN后总酚和类黄酮含量升高,且接种处理与未接种对照间总酚和类黄酮含量的差别随症状表现的加重有递增趋势;就部位而言,与根部及叶部相比,坏死严重的叶脉中总酚和类黄酮含量增加幅度最大,其含量分别增加了149.23%和152.97%;其PPO活性在接种PVYN后3d时出现第一个高峰,比对照高213.61%,随后降至最低,但仍比对照高130.77%,在接种PVYN后15d,坏死症状表现严重时,又迅速升高。抗病品种VAM接种PVYN后无异常症状,其总酚和类黄酮含量也升高,但升高幅度不大,不同部位总酚及类黄酮含量增加的幅度也均小于25%,其PPO活性在接种PVYN后稍有升高,但基本保持一个水平。  相似文献   

5.
A method is described for the estimation of residues of the carbamate insecticide promacyl [5-methyl-m-cumenyl butyryl(methyl)carbamate] and its metabolites that are hydrolysable to isothymol (m-cymen-5-ol), using high-performance liquid chromatography with electrochemical detection to determine the isothymol. Clean-up of samples relied on the steam volatility of phenols. Recoveries at the 0.1 mg kg?1 level varied from 72–88% for fat tissue and 81–91% for liver. The limits of detection were found to be 0.01 mg kg?1 for and 0.02 mg kg?1 for liver. A comparative study of the chromatography of sample extracts using both ultraviolet detection and electrochemical detection showed a substantial decrease in the level of interfering co-eluates in the latter method. A field trial, involving a single spray application of the formulated acaricide on milking cattle, revealed residues in the butter fat comparable with those found in a previous investigation.  相似文献   

6.
番茄灰霉病菌拮抗放线菌的筛选、鉴定及其活性评价   总被引:2,自引:0,他引:2  
从安徽省寿县农田土壤中分离筛选到1株对番茄灰霉病菌Botrytis cinerea有强拮抗作用的放线菌菌株HNU-1。根据菌体形态特征、培养特征、细胞壁组分、生理生化特性和16S rRNA基因序列分析,将该菌株鉴定为吸水链霉菌Streptomyces hygroscopicus。菌株HNU-1发酵滤液可抑制灰霉病菌菌丝生长和分生孢子萌发,且浓度越高,抑制能力越强;当发酵滤液稀释6.67倍时则完全抑制灰霉病菌菌丝生长和分生孢子萌发。盆栽试验结果表明,菌株HNU-1发酵滤液6.67倍稀释液对番茄灰霉病的预防与治疗效果分别为87.8%和77.9%,均显著高于50%多菌灵可湿性粉剂500倍稀释液。  相似文献   

7.
The objective of the present work was to select stable well-characterized strains of Verticillium dahliae that could be used as biological tools in genetic and plant–microbe interaction studies. Hyaline mutants, known for their stability in pathogenicity were chosen for the study. Diversity in pathogenicity was found among hyaline subclones obtained from a defoliating wild-type clone, but not within those from nondefoliating ones. Most subclones from the defoliating clone had parental pathotypes, but one (V7-2) exhibited weak pathogenicity. This subclone (V7-2), together with a highly virulent one (V7-7) deriving from the same defoliating parent clone (7), were selected for further characterization, because of their differences in pathogenicity. When studied on the basis of their growth requirements, the two subclones expressed marked differences. V7-7 grew better than V7-2 over a wider range of temperature conditions. Both subclones grew similarly in media supplemented with NH4 as nitrogen source, but in those with NO3, V7-7 grew more vigorously than V7-2 and only the former could grow when NO2 was used. In spite of these differences, the two subclones were found to belong to the same vegetative compatibility group, confirming their genetic proximity. These results highlight the physiological and genetic complexity inherent in V. dahliae . In view of their characteristics, the clones obtained in this study should prove to be valuable tools in furthering the understanding of genetic and host– V. dahliae interactions.  相似文献   

8.
ABSTRACT Localization of hydrogen peroxide (H(2)O(2)) and the roles of peroxidases, malondialdehyde, and reduced glutathione in three apple cultivars were compared in healthy trees, trees infected with apple proliferation phytoplasma (APP), and trees that had recovered from the infection. In recovered apple trees, symptoms of the disease and the pathogen had disappeared from the canopy, but phytoplasmas remained in the roots. H(2)O(2) was detected cytochemically by its reaction with cerium chloride to produce electron-dense deposits of cerium perhydroxides.H(2)O(2) occurred in the plasmalemma of the phloem of leaves of recovered apple trees, but not in healthy or APP-infected leaves. In all cultivars, the peroxidase activity detected in tissue from APP-diseased trees was greater than or equal to that of tissue from recovered trees, which equaled or exceeded that of tissue from healthy trees, at two sampling times (May and September). In contrast, the glutathione content of leaves decreased in the reverse order. More malondialdehyde was observed in leaves from recovered trees than in leaves from healthy or APP-infected trees in three of six cultivar-date combinations; in the other three combinations, the malondialdehyde contents of leaves from healthy, infected, and recovered trees were not significantly different from one another. The results suggest that some components of the oxidant-scavenging system in recovered leaves are not very active, leading to an overproduction of H(2)O(2) and, possibly, to a membrane lipid peroxidation.The production of H(2)O(2) appears to be involved in counteracting pathogen virulence.  相似文献   

9.
Blackberry leaf mottle-associated virus (BLMaV) is a recently described emaravirus associated with yellow vein disease, the main constraint of blackberry production in the southern USA. The population structure and genetic variation of BLMaV, based on the nucleocapsid and movement protein genes was resolved. BLMaV diversity is low when compared to other emaraviruses, with the genes studied being under strong negative selection. Phylogenetic analyses suggest long distance migration of the virus whereas incongruent phylogenetic relatedness and predicted reassortment events suggest that genetic exchange could play an important role in BLMaV evolution. A quantitative PCR (qPCR) protocol was developed based on the knowledge obtained through the population structure of the virus; this is a sensitive test able to detect all the isolates studied. The assay was optimized and applied successfully on multiple samples collected from several regions in the United States. Comparison between a previously developed test and the new protocol illustrated that the latter is at least 1000 times more sensitive.  相似文献   

10.
European Journal of Plant Pathology - Black rot of crucifers caused by Xanthomonas campestris pv. campestris (Xcc) is one of the most destructive diseases affecting vegetable Brassica crops, as...  相似文献   

11.
瓜黑星病菌、枯萎病菌和蔓枯病菌的三重PCR检测   总被引:2,自引:0,他引:2  
通过测定黄瓜黑星病菌(Cladosporium cucumerinum)rDNA的ITS序列,比对近缘种及瓜类几种重要病原菌的ITS序列,设计出特异性引物HX-1/HX-2,经过对引物HX-1/HX-2PCR条件的优化,可以扩增出1条190bp的黄瓜黑星病菌特异性DNA条带,灵敏度达到1pg/μL。进一步将引物HX-1/HX-2和瓜类枯萎病菌、瓜类蔓枯病菌特异检测引物Fn-1/Fn-2、Mn-1/Mn-2组合,建立三重PCR体系,可一次检测出瓜类黑星病菌、瓜类枯萎病菌、瓜类蔓枯病菌3种瓜类植物重要的病原菌。建立了可以应用于田间瓜类黑星病菌PCR检测技术和瓜类主要病害三重PCR检测技术,对瓜类病害的诊断和防治具有重要的指导作用。  相似文献   

12.
The effects of infections of Trichinella spiralis on 10 specific-pathogen-free Beagles were examined. Eight puppies received either 100, 500, 1,000, or 5,000 larvae, and 2 adult dogs received 1,000 larvae. Blood was drawn every 4 days, beginning 5 days before infection, for the determination of relative eosinophil numbers. Creatine kinase levels were monitored before infection, two weeks after infection, and one month after infection. The dogs were euthanized 1 month postinfection, and larvae were counted in muscle digests of 10 gram samples of diaphragm, pectoralis superficialis, masseter, biceps brachii, and vastus lateralis. The dogs displayed minor signs of gastrointestinal upset during the first week after infection. The dogs also developed a slight eosinophilia with a magnitude that was dependent on the number of larvae the dog received. All infected dogs, but one that had received 500 larvae, had a positive reaction with larval excretory-secretory products of T. spiralis; adult dogs had the greatest immunologic response. The creatine kinase levels were found not to be related to either the time postinfection or the magnitude of the larval dose. The number of larvae recovered from the muscles (maximum of 70 per gram) was dependent on the dosage of larvae received, but there was no significant predilection of the larvae for any of the five examined muscle groups.  相似文献   

13.
一株生防内生真菌的分离筛选、鉴定及抑菌特性   总被引:4,自引:1,他引:4  
为获取优良植物病害生防菌,以交链孢菌Alternaria tenuis Ness和尖镰孢菌Fusarium oxysporum Schlecht为指示菌,采用平板对峙培养法、抑菌圈法和菌落直径法对健康龙柏鳞叶小枝中分离的4株优势内生真菌进行了筛选评价,并结合形态学观察及ITS序列分析对筛选出的生防内生真菌进行了鉴定。结果表明,对峙培养发现1菌株对交链孢菌和尖镰孢菌均具有较好的抑制作用,抑菌率分别为52.05%和48.65%,标记其为LB-1;LB-1菌株与指示菌对峙培养的菌落交界面处,2种指示菌的菌丝均出现了消解、断裂,而LB-1的菌丝则生长正常。未灭菌LB-1菌株发酵液对交链孢菌和尖镰孢菌产生的抑菌圈直径分别为14.1 mm和13.7 mm,抑菌率分别为47.89%和48.72%;灭菌LB-1菌株发酵液对交链孢菌和尖镰孢菌的抑菌圈直径分别为15.3 mm和15.0 mm,抑菌率分别为5.96%和33.90%,指示菌在生长过程中菌丝溶解现象明显。经鉴定,LB-1菌株为毛壳菌属Chaetomium中的近缘毛壳菌C.subaffine,是一种极具生防潜力的内生真菌,其抑菌特性可能通过溶菌作用实现。  相似文献   

14.
Calonectria pseudonaviculata causes lesions on boxwood leaves and twigs. Controlled-environment experiments were conducted to determine the effects of temperature and leaf wetness period on C. pseudonaviculata sporulation on diseased (cv. Suffruticosa) leaves and of dryness periods and high temperature on conidial survival. Infected leaves were incubated in moist chambers and subjected to six temperatures (9, 13, 17, 21, 25, and 29°C) and six leaf wetness periods (0, 12, 24, 40, 48, and 72 h). Spore production was influenced significantly by wetness period, temperature, and their interaction. Increasing duration of leaf wetness and increasing temperature generally increased sporulation, with no sporulation occurring at 29°C or 9 and 13°C, except at 72 h of wetness exposure, while it was optimal at 21°C. Detached leaves with profuse conidia were subjected to a range of drying (relative humidity at 65%) times (0, 2, 4, 6, and 8 h) at two temperatures of 21 and 29°C. Conidia were then harvested and plated on water agar. Germinating conidia were counted to measure the spore viability. Spore mortality increased with increasing dryness duration at both temperatures but occurred more quickly and severely at 29 than 21°C. Overall, this study extended biological knowledge of conditions required for crucial stages of the C. pseudonaviculata disease cycle and the obtained results will be vital for developing boxwood blight forecasting and management tools.  相似文献   

15.
Considering the economic importance of anthracnose, caused by Colletotrichum sublineolum, and silicon (Si) to enhance sorghum resistance against this disease, this study aimed to investigate the effect of this element on leaf gas exchange and also the antioxidative system when infected by C. sublineolum. Plants from sorghum line CMSXS142 (BR 009 [Tx623] - Texas), growing in hydroponic culture with (+Si, 2 mM) or without (-Si) Si, were inoculated with C. sublineolum. Disease severity was assessed at 2, 4, 6, 8, and 10 days after inoculation (dai) and data were used to calculate the area under anthracnose progress curve (AUAPC). Further, the net carbon assimilation rate (A), stomatal conductance to water vapor (g(s)), internal-to-ambient CO? concentration ratio (C(i)/C(a)), and transpiration rate (E); the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR); the electrolyte leakage (EL), and the concentrations of hydrogen peroxide (H?O?) and malondialdehyde (MDA) were determined. The AUAPC was reduced by 86% for the +Si plants compared with the -Si plants. The values of A, g(s), and E were lower upon inoculation of -Si plants in contrast to inoculated +Si plants with decreases of 31 and 60% for A, 34 and 61% for g(s), and 27 and 57% for E, respectively, at 4 and 8 dai. For the noninoculated plants, there was no significant difference between the -Si and +Si treatments for the values of A, g(s), and E. The C(i)/C(a) ratio was similar between the -Si and +Si treatments, regardless of the pathogen inoculation. The activities of SOD, CAT, APX, and GR tended to be higher in the +Si plants compared with the -Si plants upon inoculation with C. sublineolum. The EL significantly increased for -Si plants compared with +Si plants. The MDA concentration significantly increased by 31 and 38% at 4 and 8 dai, respectively, for the -Si plants compared with the +Si plants. Based on these results, Si may have a positive effect on sorghum physiology when infected by C. sublineolum through the maintenance of carbon fixation and also by enhancing the antioxidant system, which resulted in an increase in reactive oxygen species scavenging and, ultimately, reduced damage to the cell membranes.  相似文献   

16.
利用异源表达于酵母细胞中的小麦细胞色素P450cDNA(CYP71C6v1)研究了磺酰脲类除草剂绿磺隆、醚苯磺隆的代谢作用。结果表明,代谢产物5-羟基绿磺隆和5-羟基醚苯磺隆能够抑制乙酰乳酸合成酶(ALS酶)活性,且代谢产物与母体化合物绿磺隆、醚苯磺隆抑制ALS酶活性的IC50值差异小,但是代谢产物在茎叶喷雾小麦和菜豆时,均未表现出活性。绿磺隆及其代谢产物抑制小麦ALS酶活性的IC50值分别为7.1×10-9和7.9×10-9mol/L,抑制菜豆ALS酶活性的IC50分别为3.6×10-9和4.1×10-9mol/L;醚苯磺隆及其代谢产物抑制小麦ALS酶活性的IC50分别为4.6×10-9和5.3×10-9mol/L,抑制菜豆ALS酶活性的IC50分别为4.7×10-9和4.9×10-9mol/L。结果表明,在磺酰脲类分子苯环5位上进行结构改造,有可能得到高活性的化合物。  相似文献   

17.
花生青枯病内生拮抗细菌的鉴定、抗菌活性及其田间防效   总被引:1,自引:0,他引:1  
从病区健康花生植株茎秆内分离到1株对花生青枯病菌Ralstonia solanacearum有强拮抗作用的内生细菌,命名为BZ6-1菌株.拮抗试验表明,该菌具有较广抗菌谱,对多种植物病原真菌有较强的抑制作用.形态观察和16S rDNA同源性分析初步鉴定为解淀粉芽孢杆菌Bacillus amyloliquefaciens.该菌的最佳培养基组成为:糖蜜10g·L-1,蛋白胨0.5g·L-1,酵母膏0.5g·L-1.最适发酵条件为pH8.5、装液量50mL/250mL、温度25℃、转速200r·min-1、培养时间21h,在此条件下拮抗圈直径达34.0mm.田间试验结果表明BZ6-1菌株对花生青枯病防效达62.3%.  相似文献   

18.
A method is described for the simultaneous determination of residues of five fungicides used for foliar treatment of apple and pear trees, and for postharvest application. After extraction, the mixture of these fungicides is cleaned-up on a ‘SEP PAK C18’ cartridge and the components determined by gas-liquid chromatography with electron-capture detection. The minimum detectable amounts in apples and pears, on a fresh weight basis, were 0.005mg kg−1 for vinclozolin, 0.010mg kg−1 for captan, folpet and iprodione, and 0.020 mg kg−1 for captafol. The percentage recovery for each fungicide (calculated by analysing four samples of untreated apples and pears, to which varying concentrations of each active ingredient had been added) varied for vinclozolin between 70.0 and 89.2, for captan between 72.0 and 83.8, for folpet between 73.0 and 93.0, for captafol between 70.8 and 91.8, and for iprodione between 75.1 and 97.1.  相似文献   

19.
20.
By means of a fluorescein conjugated antiserum, local aggregation of antigenic material in narcissus leaves infected with yellow stripe virus was demonstrated in the cytoplasm of epidermal and parenchyma cells. By comparing results obtained by fluorescent-microscopy with those obtained by light and electron microscopy it is reasonable to assume that the antigenic material consists of aggregates of virus particles.  相似文献   

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