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1.
Monoclonal antibodies have been raised against an haustorium-enriched sample prepared from flax leaves infected with the biotrophic flax rust pathogen Melampsora lini. The monoclonal antibodies were produced following conventional and co-immunisation procedures and the range of antibody specificities was compared. The preparation used as immunogen for the conventional protocol was a crude isolate of haustoria consisting of approx. 65% fungal haustoria, the other components being mainly mesophyll cells or cell wall and chloroplast fragments. Following hybridoma production, 40% of positive cell lines produced antibodies that reacted with haustoria and other fungal cells, but 60% bound to plant cells in the infected leaves. For the co-immunisation protocol, the preparation used for immunisation consisted of the crude isolate of haustoria mixed with serum raised against an haustorium-depleted leaf homogenate. In two fusions, 92-94% of the antibodies reacted with fungal cells, including 3 cell lines that localised specifically to the cell wall of haustoria. Only 6-8% of the antibodies produced via co-immunisation reacted with plant cells. The antigens targeted by the three haustorium-specific monoclonal antibodies are incorporated into the wall at early stages of haustorium development, remain in the wall throughout haustorium maturation, and are present in both compatible and incompatible interactions. The epitopes recognised by the monoclonal antibodies are oligosaccharide in nature and the antigens are highly resistant to extraction from the wall. These results highlight the value of the co-immunisation protocol for the production of monoclonal antibodies to specific components in an impure preparation and provide direct evidence for molecular differentiation within the wall of the haustorium of M. lini.  相似文献   

2.
过氧化物酶和苯丙氨酸解氨酶与毛白杨抗锈性的关系   总被引：20，自引：2，他引：20  
 叶锈菌的侵染使寄主的过氧化物酶和苯丙氨酸解氨酶(PAL)活性均增加,且高感无性系的酶活性变化幅度较高抗无性系的大。其中,过氧化物酶活性高峰出现的时间因抗、感无性系受侵染后显症时间的不同而有差异;但PAL酶活性高峰则不论抗、感病无性系,均在接种后第10天左右出现。侵染还可引起过氧化物酶同工酶谱的变化,使多数供试无性系有新酶带出现。但过氧化物酶同工酶谱的变化不能明确反映寄主的抗病性差异。  相似文献   

3.
抗白粉病胡麻种质资源田间鉴定与筛选   总被引：2，自引：0，他引：2  
白粉病目前已成为影响胡麻产量和质量最常见的病害之一, 种植抗病品种是防控病害最经济环保的有效措施, 然而抗病亲本材料的缺乏已成为制约抗病品种选育的关键因素。为筛选出抗白粉病胡麻材料, 本研究在田间自然感病的条件下, 采用病情指数法对300份国内外胡麻种质资源材料进行了抗白粉病鉴定和评价。结果表明, 所有供试材料均程度不同地感染胡麻白粉病, 无免疫材料, 仅有5份材料为中抗; 其余295份均为感病材料, 其中8份材料中感, 52份材料感病, 235份材料高度感病。本研究可为抗白粉病胡麻品种的培育及相关抗病基因的发掘提供参考。  相似文献   

4.
Representative European wheat cultivars were tested under quarantine containment for their susceptibility to Tilletia indica, the cause of Karnal bunt of wheat. Fifteen winter and 15 spring wheat ( Triticum aestivum ) and 11 durum wheat ( Triticum durum ) cultivars were inoculated by boot injection just prior to ear emergence to test their physiological susceptibility. Selected cultivars were then re-tested by spray inoculation after ear emergence to determine their morphological susceptibility, which is a better predictor of field susceptibility. At maturity, the ears and seeds were assessed for incidence and severity of disease. For the physiological susceptibility tests, 13/15 winter wheat cultivars were infected and the percentage of infected seeds ranged from 1 to 32%. For spring cultivars, 13/15 cultivars were infected and the percentage of infected seeds ranged from 1 to 48%. For the durum cultivars, 9/11 were infected and the percentage of infected seeds ranged from 2 to 95%. Across all cultivars, 35/41 were infected. Based on historical Karnal bunt susceptibility categories using coefficients of infection, one cultivar was classed as highly susceptible, three as susceptible, 11 as moderately susceptible, 20 as resistant and only six as highly resistant. The spray-inoculation morphological susceptibility tests broadly confirmed the physiological susceptibility results, although lower levels of infection were observed. Overall, the range of susceptibility was similar to that found in cultivars grown in Karnal bunt affected countries. The results demonstrate that European wheat cultivars are susceptible to T. indica and thus could potentially support the establishment of T. indica if introduced into Europe.  相似文献   

5.
 本文研究了栽培大麦×纤毛鹅观草属间杂种后代60个系群及其亲本在接菌条件下的抗赤霉病表现。从每穗发病百分率、发病动态进程和穗轴病变率等多个侧面对属间杂种后代系的抗性进行了分析。结果表明:1.发病百分率:参试各系未出现高抗(小穗受害率< 3.93%)和高感(小穗受害率> 57.3%)的类型。后代系属R级(抗病)的共7系,占11.7%;属MR级(中抗)的共25系,占41.7%;其余28系属MS级(中感)和S级(感染),占46.7%。当按病情指数来划分时,则R级和MR级所占比例更大。2.变动系数:属抗病级的各系,在接菌后第8 d的第一次调查中,基本上未发病,以后各期的变动系数均小;属感病级的各系,第一次调查时感病就重,以后各期的变动系数也高。3.属抗病的各系,穗轴节的病变最轻,感病各系较重,大麦亲本最重。此外,还讨论了作物对赤霉病抗性的机理、抗性级别划分标准和属间基因转移等问题。  相似文献   

6.
本文研究了栽培大麦×纤毛鹅观草属间杂种后代６０ 个系群及其亲本在接菌条件下的抗赤霉病表现。从每穗发病百分率、发病动态进程和穗轴病变率等多个侧面对属间杂种后代系的抗性进行了分析。结果表明：１发病百分率：参试各系未出现高抗（小穗受害率＜ ３９３％ ）和高感（小穗受害率＞ ５７３％ ）的类型。后代系属Ｒ 级（抗病）的共７ 系,占１１７％ ;属ＭＲ 级（中抗）的共２５ 系,占４１７％ ;其余２８ 系属Ｍ Ｓ级（中感）和Ｓ级（感染）,占４６７％ 。当按病情指数来划分时,则Ｒ 级和ＭＲ 级所占比例更大。２变动系数：属抗病级的各系,在接菌后第８ ｄ 的第一次调查中,基本上未发病,以后各期的变动系数均小;属感病级的各系,第一次调查时感病就重,以后各期的变动系数也高。３属抗病的各系,穗轴节的病变最轻,感病各系较重,大麦亲本最重。此外,还讨论了作物对赤霉病抗性的机理、抗性级别划分标准和属间基因转移等问题。  相似文献   

7.
Two representative Italian emmer wheat (Triticum dicoccum) landraces, two selected lines and three improved emmer wheat cultivars, derived from crosses with durum wheat (Molisano landrace × ‘Simeto’), were tested for their susceptibility to Tilletia indica, the cause of Karnal bunt of wheat. Plants of emmer wheat were inoculated by injecting allantoid sporidial suspensions into the boot cavity of plants, just prior to ear emergence. A highly susceptible Indian spring wheat cultivar (Triticum aestivum) was used as a comparative control. At maturity of the plants, the seeds were harvested and assessed for incidence and severity of disease. All emmer wheat genotypes tested were infected but showed differing levels of susceptibility. The percentage of infected seeds for individual genotypes ranged from 5.4 to 75.0% compared with 99.1% for WL-711. The severity of infection was less in the old landraces, but it was higher in all the improved emmer wheat cultivars. In conclusion, Italian cultivars of emmer wheat were found to be highly susceptible to T. indica, and are potentially able to support the establishment of the pathogen.Authors L. Riccioni and M. Valvassori contributed equally to this work and should both be considered as first author.  相似文献   

8.
ABSTRACT A precise real-time polymerase chain reaction (PCR) assay was developed for quantifying Verticillium albo-atrum DNA. The assay was used in a repeated experiment to examine the relationship between the quantity of pathogen DNA detected in infected leaves and shoots and the severity of Verticillium wilt symptoms in several alfalfa cultivars expressing a range of disease symptoms. Plants were visually inspected for symptoms and rated using a disease severity index ranging from 1 to 5, and the quantity of pathogen DNA present in leaves and stems was determined with real-time PCR. No significant differences in pathogen DNA quantity or disease severity index were observed for experiments or for cultivar-experiment interactions. Significant differences were observed between cultivars for the quantity of pathogen DNA detected with real-time PCR and also for disease severity index ratings. In both experiments, the highly resistant check cultivar Oneida VR had significantly less pathogen DNA, and significantly lower disease severity index ratings than the resistant cultivar Samauri, the moderately resistant cultivar Vernema, and the susceptible check cultivar Saranac. In both experiments, the Spearman rank correlation between the amount of V. albo-atrum DNA detected in leaves and stems with real-time PCR and disease severity index ratings based on visual examination of symptoms was positive (>0.52) and significant (P < 0.0001). These results suggest that resistance to Verticillium wilt in alfalfa is characterized by a reduced colonization of resistant genotypes by the fungus.  相似文献   

9.
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   

10.
ABSTRACT Progeny of rust-resistant, open-pollinated slash pine families exhibited components of partial resistance in greenhouse tests. Nine-month-old seedlings of some resistant families had (i) a greater frequency of short galls (相似文献   

11.
Tan spot caused by Pyrenophora tritici-repentis is the main foliar diseases of wheat in Brazil. The effect of silicon (Si) on the components of resistance of a susceptible (Fundacep Horizonte) and a moderately resistant (Quartzo) wheat cultivar was studied in a controlled environment. Silicon was supplied as calcium silicate in the soil 30 days before sowing. At the booting stage, a conidial suspension of the fungus was sprayed onto the flag leaves of potted plants, which were incubated under moist conditions for 48 h. Afterwards, inoculated leaves were assessed for: incubation period (IP), infection efficiency (IE), area under lesion size curve (AULSC), lesion size (LS), severity (SEV) and area under severity curve (AUSC). Foliar Si concentrations were quantified at the end of the evaluations. Si supply to plants increased leaf Si concentration in 233% for Fundacep Horizonte (from 4.8 to 16.0 g kg?1 of dry matter) and 211% for Quartzo (from 5.3 to 16.5 g kg?1 of dry matter). In the Si + treatments, IP was longer by 24 and 17 h, IE declined by 53.5 and 65.5%, LS (at 264 h after inoculation) by 4.6 mm (from 9.5 to 4.9 mm) and 5.9 mm (from 8.2 to 2.3 mm), and SEV by 53% (from 54.4 to 18.8%) and 88% (from 47.7 to 5.5%) respectively, for the Fundacep Horizonte and Quartzo cultivars. The Si x cultivar interaction was not significant for AULSC and AUSC, and these variables were reduced by 55.8 and 80.8%, respectively, in plants supplied with Si. In conclusion, Si enhanced the resistance of wheat plants to tan spot development by affecting several resistance components, regardless of the resistance level of the cultivar. However, the greatest reduction in tan spot development by Si supply was observed when using a moderately resistant cultivar.  相似文献   

12.
Yield losses due to rust and angular leaf spot (ALS) of snap beans may reach 100% in Eastern Africa. Where susceptible varieties are grown, farmers control these diseases with routine fungicide applications. To determine an optimum application rate and spray schedule for Orius® (tebuconazole 250 g/L), we sprayed 10 mL and 20 mL Orius® per 15 L spray water twice at two trifoliate leaf stage and 50% flowering, and three times at the same stages, with an additional application at pod initiation. In farmers’ fields, we tested the effect of fungicide sprays, use of resistant variety, intercropping, increased plant spacing and farmyard manure on rust and ALS diseases. Application three times of 20 mL Orius® per 15 L spray water reduced rust severity scores by 5.7 and 2.4 in 2010 and 2011, respectively. Lowest rust and ALS severities were observed when a resistant variety, fungicide or farmyard manure was used. Pod yield increments due to disease management ranged between 13% and 242%. Prophylactic fungicide application, use of resistant varieties and farmyard manure can be used to reduce disease severity and improve snap bean quality on smallholder farms.  相似文献   

13.
A study on biochemical factors involved in black pepper defense response against Phytophthora capsici, was carried out in P. capsici susceptible (Sreekara) and resistant (04-P24, shows root resistance to the pathogen) black pepper lines. Seven important factors – change in membrane conductance, total phenols, orthodihydroxy (OD) phenols, lignin and defense related enzymes (peroxidase, β-1,3 glucanase and β-1,4 glucanase) – were studied under uninoculated and pathogen (P. capsici, isolate 06-04) inoculated condition to know the preformed and induced responses. The pathogen was inoculated (soil inoculation) and plants were observed for changes, at 24 h intervals for 10 days. On 8th day after inoculation symptoms started appearing on Sreekara and increased the severity till 10th day. Both root and stem samples were subjected for biochemical analysis. Of the factors analyzed, it was found that membrane conductance, OD phenol, lignin and peroxidase activity play significant role in root resistance to P. capsici in 04-P24. Light microscopy of the portion of root – where pathogen found attached – was also done.  相似文献   

14.
小麦旗叶和穗部吲哚生物碱含量与抗麦长管蚜关系研究   总被引：10，自引：1，他引：10  
采用蚜量比值法评价了 8个小麦品种 (系)对麦长管蚜的抗性 ,结果显示 ,高抗、抗、中抗、感虫品种 (系 )分别有 1、1、3、3个。进而研究了不同抗蚜品种 (系 )小麦旗叶和穗部的吲哚生物碱含量及其与抗蚜性的关系。结果表明 ,大多数抗蚜品种 (系 )的旗叶和穗部吲哚生物碱含量均高于感蚜品种 (系 ) ,尤其穗部。不同抗性级别的小麦品种 (系 )吲哚生物碱含量与蚜量比值的相关分析显示 ,穗部吲哚生物碱含量与蚜量比值的相关系数为-0.8633,而旗叶的相关系数为-0.3983,表明小麦旗叶吲哚生物碱含量与抗麦长管蚜具有一定的相关性 ,而穗部则呈显著的相关性  相似文献   

15.
Gal-On A  Wolf D  Wang Y  Faure JE  Pilowsky M  Zelcer A 《Phytopathology》1998,88(10):1101-1107
ABSTRACT Tomato breeding lines were transformed with a defective replicase gene from RNA 2 of cucumber mosaic virus (CMV). A total of 63 transformants from five tomato genotypes were evaluated for resistance to CMV strains. The responses of R1 transgenic offspring fit into three categories: fully susceptible lines (44%), fully resistant lines (8%), and an intermediate-type mixture of susceptible and resistant seedlings in variable proportions (48%). Further characterization of the response of two highly resistant lines was performed by mechanical inoculation, aphid transmission, or grafting experiments. No virus was detected in noninoculated leaves from these lines, although a low level of virus accumulated initially in the inoculated leaf. The homozygous R2 plants and further generations that were evaluated (up to R5) showed resistance to the Fny-CMV strain, two Israeli isolates tentatively classified as subgroup IA, and K-CMV (a representative of subgroup IB). These lines were partially resistant to LS-CMV (a representative of subgroup II) when a high-virus-titer inoculum was used. Expression of the viral transgene was verified in these lines; however, the expected translation product was not detectable. In grafting experiments, we demonstrated that CMV virions were blocked in their ability to move from infected rootstocks of nontransformed tomato or tobacco into the transgenic scions. Interestingly, virions could not move through a transgenic intersection into the upper scion. These results provide an additional indication that replicase-mediated resistance affects long-distance movement.  相似文献   

16.
 本文论述了不同抗性番茄品种在接种了TMV之后体内过氧化物酶及其同工酶的变化趋势。不同品种番茄幼苗接种TMV之后30天内病毒含量、过氧化物酶活性及其同工酶的测定结果表明:所有接种的番茄幼苗与健株对照相比均表现酶活性的增强及酶带数目的增多;但不同抗性品种,酶活性交化曲线及同工酶谱带的变化趋势有所不同:感性品种北京早红(+/+)及耐病品种强力米寿接种TMV之后,病毒含量迅速上升,在第15天达到最高峰,同时植株开始显症,其酶活性曲线呈现出1个增值高峰,即酶活性只在显症之后迅速上升于第24天达到最高峰,病株在症状发展过程中产生2条健株所没有的具高迁移率的同工酶谱带A与B。抗性品种Tm-2(Tm-2/+)抑制TMV在体内的增殖,在接种之后30天内植株不表现典型外部症状,其酶活性曲线具有2个增酶高峰,即在接种后第12天达到最高峰,并在第21天有1个新的高峰;在酶活性高峰期,接种植株也产生同工酶谱A与B,与感性品种不同的是谱带A与B形成较早,同时,抗性品种还产生感病品种所没有的1条同工酶谱带F。上述过氧化物酶活性及同工酶的变化趋势可以成为鉴定品种抗性一个有价值的生化指标。  相似文献   

17.
The bioherbicidal efficacy of different alginate formulations of Alternaria eichhorniae 5 (isolate Ae5), a virulent Egyptian isolate, was compared on waterhyacinth (Eichhornia crassipes). The fungus was formulated as alginate pellets containing mycelium alone, mycelium plus culture filtrate or culture filtrate alone. Each formulation was applied with and without a hydrophilic humectant (Evergreen 500). These formulations were evaluated for disease incidence (DI), and disease severity (DS). Maximum DS, but not DI, was obtained with the alginate pellets of mycelium plus culture filtrate. Alginate formulations supplemented with the hydrophilic polymer were more effective in promoting disease. Physiological changes associated with the treated waterhyacinth plants were determined 3, 6 and 9 days after treatment. Waterhyacinth plants treated with alginate pellets of mycelium plus culture filtrate of Ae5 had the lowest levels of pigments, carbohydrates and relative water content. Infection of waterhyacinth with Ae5 led to a significant increase in total phenols of leaves as compared to control. Penetration of waterhyacinth leaves by the fungus occurred only through the stomata, and the invading hyphae were located in the intercellular spaces of leaf tissues. Cytological changes noted in infected cells included changes in chloroplast, nucleus and mitochondria. Invagination of the plasma membrane, particularly at plasmodesmata was also noticed in infected cells. The associations between the infection process, the physiological disorder and the ultrastructure of infected leaves are discussed.  相似文献   

18.
MDMV HC-Pro在玉米叶片中的积累及免疫定位   总被引：3，自引：0，他引：3  
 本文以感病自交系Mo17、掖107和抗病自交系黄早四为材料,研究了玉米矮花叶病毒(MDMV)和MDMV辅助成份-蛋白酶(HC-Pro)在叶片中的积累动态和细胞内定位。结果表明,在接种后3 d,MDMV就在掖107和Mo17接种叶的上位叶积累到了相当高的程度,6 d后达到高峰;而MDMV在黄早四中的浓度一直低于在掖107和Mo17中的浓度。在接种掖107和Mo176 d后,MDMV HC-Pro在上位叶中的积累到达高峰,而在黄早四植株中MDMV HC-Pro直到第9 d才到最高,而且浓度一直低于感病自交系掖107和Mo17。麦二叉蚜从发病植株上获毒后的传毒效率变化与MDMV、MDMV HC-Pro在叶片中的积累动态一致。通过胶体金标记对MDMV HC-Pro进行免疫定位,发现在细胞质中、与质膜相联系的风轮状内含体、片层凝集状内含体、细胞质高密度物质和病毒粒子周围有金标记,说明在这些部位有MDMV HC-Pro的存在。  相似文献   

19.
Two-week-old seedlings of two rice varieties, resistant CH13 and susceptible Benibhog, were inoculated with a conidial suspension ofHelminthosporium oryzae. The resistant host exhibited greater peroxidase activity than the susceptible one when infected with the pathogen. Enzyme activities were measured 0, 24, 48, 72, 96 and 120 h after infection. Peroxidase activity in diseased leaves bearing young lesions,i.e., 24 h after inoculation, was not appreciably different from that in non-infected leaves. At the intermediate and mature stages of lesion development,ri.e., 72 and 120 h after inoculation, a marked increase in peroxidase activity was observed. The pattern of increased enzyme activity was similar in both varieties but the whole event proceeded faster in the resistant variety. No marked change in peroxidase activity in healthy leaves of both the varieties was noticed with increase of seedling age.  相似文献   

20.
This study aimed to develop and validate a standard area diagram set (SADS) to quantify the severity of blast, caused by Pyricularia oryzae, on wheat leaves. The SADs has ten levels: 0.1, 1, 5, 10, 22, 32, 42, 52, 62 and 72 % blast severity. To validate the SADs, 12 inexperienced raters estimated disease severity on 50 images of leaves from cultivars BR-18 (susceptible) and BRS-229 (partially resistant). Blast severity was first estimated without the use of the SADs on 50 leaves with a range of blast severity. The same raters evaluated the same 50 leaves using the SADs as an aid. The SADs improved accuracy (coefficient of bias, C b ?=?0.88 and 0.99, without and with SADs, respectively) and agreement (Lin’s concordance correlation coefficient, ρ c ?=?0.84 and 0.96 without and with SADs, respectively) of the estimates of severity. The absolute error was (-) 52 % without the SADs and (-) 24 % when using SADs as an aid. Severity estimates were more reliable when using SADs (R2?=?0.87 unaided and R2?=?0.92 with SAD). The SADs proposed in this study will improve accuracy and reliability of estimates of blast severity on wheat leaves.  相似文献   

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