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The effect of modified bacterial virulence to host-pathogen relationship (Phaseolus vulgaris L. Pseudomonas savastanoi pv. phaseolicola)
53-56.Views:173The Pseudomonas savastanoi pv. phaseolicola is one of the most expressive biogen stressors of the bean (Phaseolus vulgaris L.) in Hungary. The chemical and agrotechnological defence is inefficient, so breeding is the only workable way. The conventional cultivars are susceptible to PS while most of the new industrial varieties have genetic resistance to the pathogen. The genetic background of resistance is, however, a complex system in the bean. Leaf resistance is a monogenic system, but this gene is not expressed in juvenile stage of the host. The pathogen species can be divided into different races. After inoculation with virulent strains, typical symptoms appeared on the leaves. To understand the details of host-pathogen relationships, there were carried out experiments using bacterial strains with altered virulence. Six transposon mutants of the PS were tested. Our main objective was to test these modified bacterial strains on bean cultivars of known genetic background. First we analysed the symptoms, and then the correlation between the symptoms and the multiplication of mutant bacteria. Three cultivars (Cherokee, Inka and Főnix) were tested.
The infection by the virulent PS isolate produced typical symptoms on the three cultivars tested. Mutant bacteria (except strain 756) did not cause any significant symptoms on the hosts. The mutant 756 induced visible symptoms on the cultivars Cherokee and Inka. On Cherokee there were small watersoaked lesions, and HR (hypersensitivity reaction) was detected on Inka, but this was restricted to some cells only (mikro HR). The rate of multiplication of the wild type strain was much higher than the multiplication of the mutants. Bacteria were detected in the cotyledons and primordial leaf, but there is not any substantial number of bacteria in leaves, except for strains 757, 1212 and 1213. The rate of multiplication of strain 756 was intermediate. These, and other experiments can help to understand the genetic background of resistance and the host-pathogen relationship in the Pseudomonas-bean pathosystem.
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Field trials with non-bactericide products to control fire blight in apple orchards
55-60.Views:132Recently, novel strategies and chemical agents for prophylactic protection against the bacterial (Erwinia amylovora) disease fire blight are being sought. Resistance-inducing compounds, such as prohexadione-Ca represent promising alternatives. Prohexadione-Ca is the active ingredient of the bioregulator Regalis, currently being introduced in several European countries and overseas. Another product used in this study was Biomit Plussz, a leaf fertiliser providing harmonic supply of nutrient elements, the complete supply is assumed to improve the tolerance against diseases.
Treatments' effects of both of these products were compared to the effectiveness of treatments with antibiotics repeated twice, three or four times a season.
In the years of 2001 and 2002, the effectiveness of both Regalis and Biomit Plussz in reduction of incidence of shoot blight was similar, or proved to be superior to the check treatments consisting of repeated sprayings of antibiotics. Last year (2003) treatments of streptomycin resulted — although within the same magnitude — in a somewhat better control of shoot blight than sprayings with the other compounds.
As regards severity of blossom blight, inconsistent results were recorded concerning both Regalis and Biomit Plussz.
In general, prohexadione-Ca is less efficient for controlling flower infection by E. amylovora as compared to shoot infections, since successful prophylactic treatments are difficult to carry out early in the season. The highest effectiveness in fire blight management can, therefore, be achieved by using prohexadione-Ca (as preventive protection) in combination with streptomycin or other suitable antibiotics (as curative protection).
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Mechanical and physical control in apple orchards as preventative fungal disease management
19-21.Views:250In this minreview, mechanical and physical control against apple fungal diseases among non-chemical control approaches were summarized. This overview listed five groups of mechanical and physical control methods: pruning, removal of inoculum sources, shredding of leaf litter, burying of inoculum sources and flaming of leaf litter. These methods were shown to reduce succesfully infection potential of inoculum sources in orchards and these non-chemical control measures are one of the most essential approaches for preventative fungal disease management. However, most of these methods are not widely spread in the apple-growing practice due to relatively low control efficacy, medium to high labour costs and/or time limits during the season.
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General defense system in the plant kingdom
79-84.Views:132The goal of plant breeders is to improve the resistance of crops against virus, bacterium and fungus pathogens was easiest to achieve by selection for phenotypes displaying the hypersensitive reaction. The resistant plant of that type keeps its health by preventing or delaying the systemization of the pathogen by destruction of cells and tissues of variable size or amputation of the contaminated organs. The faster the reaction of the host plant is the more efficient and economical is the defense, since the extent of tissue destruction decreases proportionally with the speed of reaction.
During a breeding program for resistance carried out on several plant species, mainly vegetables over thirty years, also an alternative defense reaction has been experienced, which fundamentally differs from the hypersensitive reaction. In that reaction the cells and tissues of the host plant being exposed to the pathogen do not die, on the contrary they hinder systemization of the pathogen by tissue thickening. An additional significant difference is that on the contrary to hypersensitive reaction this reaction is less host- or pathogen-specific and works excellently even at high temperature (over 40 °C).
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Reactions of different plant organs of pear cultivars to Erwinia amylovora infection
17-21.Views:123Research project has been initiated in 1999 with the aim of evaluating the degree of susceptibility/resistance of pear cultivars grown in Hungary to fire blight disease caused by Erwinia amylovora. The recently selected promising cultivars were also examined. Inoculation experiments were conducted in controlled greenhouse conditions because of quarantine regulations in Hungary. Following the disease process, development of symptoms of plant organs (shoots, flower parts, fruits) was observed. Suspension of two E. amylovora strains (Ea 21, Ea 23) isolated from pear was used in a mixture (5x108 cells x m1-1) for the inoculation. Twenty-six pear cultivars were examined and grouped into four categories: low susceptibility, moderately susceptible, susceptible and very susceptible. Most of the cultivars were susceptible or very susceptible while some promising 'Eldorado', 'Harrow Delight' and `Hosui' showed low susceptibility.
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Farm-scale evaluation of two widely used sanitation practices for reducing primary inoculums of apple scab in organic apple production
15-18.Views:177Effects of two widely used sanitation practices were evaluated at farm-scale level on leaf degradation and primary infection by Venturia inaequalis in an organic apple orchard (Eperjeske) on two apple cultivars (Jonathan and Prima) from 2011 to 2013. The tested sanitation practices were eradication of fallen leaves by collection and disc cultivation. Treatments of eradication of fallen leaves by collection and disc cultivation reduced signifi cantly (P< 0.001) leaf litter density with 70–85 and 40–55%, respectively, compared to untreated plots in both years. Above treatments in the same order reduced spring scab incidence with 40–50, and 10–20%, respectively, compared to untreated plots. Incidence of leaf scab in autumn was not signifi cantly lower (P< 0.05) in the treatments in the years.
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Detection and identification of phytoplasmas in peach based on woody indexing and molecular methods
35-41.Views:137Symptoms resembling phytoplasma disease have been observed on peach trees in a seed-source plantation of stone fruits in south Hungary quite recently. In this publication we report on the results of woody indexing of symptomatic peach trees on GF 305 indicator in the field and under greenhouse conditions as well as on molecular studies. Phytoplasma infection detected on GF 305 indicators in greenhouse and field indexing was confirmed by PCR. Nested PCR was conducted using universal primer pairs followed by group and subgroup specific primers for the second amplification. RFLP analysis of nested PCR products was performed using Rsal restriction enzyme. Based on the results of molecular studies it can be concluded that phytoplasmas, belonging to the European stone fruit yellows subgroup (16SrX-B) were identified in peach trees. Further studies on symptomatic peach trees originating from different parts of Hungary are in progress.
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The comparison of several soil cultivation methods in the Tokaj-wine region
35-37.Views:193Our results show that the different cultivation methods have higher effect on the yield than on the grape quality. In 2007 the weather was extreme dry (from May to August only 195 mm precipitation was recorded) the straw mulch proved to be the best solution regarding the yield and the grape quality. Although no significant differences were observed in the sugar- and titratable acidity content of the must, the ratio of noble rotted berries was higher on the straw mulched plots. Straw mulch could conserve the moisture content of the soil and it seems to be contributed to the conformation of suitable microclimate for Botrytis infection, but for long distance conclusions further examinations need to be investigated. The less yield and ratio of rot was observed in case of barely covered vines and the vegetative growth of the grape was less intensive in case of these vines.
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Research Note virus transmission by grape phylloxera (Daktulosphaira vittfoliae Fitch)
73-74.Views:124Grape phylloxera (Daktulosphaira vitifoliae FITCH) infests immature roots of both Vitis vinifera L. and phylloxera resistant rootstocks. A capability to transmit viticultural viruses would make grape phylloxera a phytosanitary threat even under conditions where direct damage by the insect is not likely. We tested the hypothesis that phylloxera could transmit grapevine fanleaf virus (GFLV) by planting infected and non-infected vines in common 10 liter pots and infecting roots of the infected vine with grape phylloxera. In this test infection of a previously non-infected plant in the absence of nematode population suggests that grape phylloxera is a vector of GFLV.
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Resistance gene Sw-5 of tomato confers resistance to TCSV in Solanum melongena
41-47.Views:137Eggplants transformed with Sw-5 gene, regenerated by organogenesis and somatic embryogenesis, were resistant to the Tomato chlorotic spot virus, while wild plants did present systemic infection. TO plants were selfed and the segregation analysis of T1 and T2 generation indicated the existence of one or more insertion sites. Southern blot analysis confirmed one or two independent insertions in T2 plants. Different lesions associated with the insertion number were observed in TI and T2 plants. T2 plants with two copies displayed faster hypersensitive reactions and characteristic necrotic lesions that contrasted with slower responses and necrotic ring lesions in plants with one copy. These results suggest that the Sw-5 confers resistance to tospovirus in transgenic eggplants and that the resistant phenotype depends on the number of transgene copies.
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Induce the plant resistance to pathogen infection
89-93.Views:360Systemic acquired resistance (SAR) is a mechanism of induced defense that confers long-lasting protection against a broad spectrum of microorganisms. Salicylic acid (SA) is the signal molecule which is required for induce SAR and is associated with accumulation of pathogenesis-related proteins, which are thought to contribute to resistance. SA paly vital role in some related resistance gene expression in plant cell which have direct or indirect effect on pathogen growth as SA has direct toxicity for pathogen and in the same time has stimulation effect for some enzyme related to reduce the oxidative burst.
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Virus susceptibility and resistance of Hungarian pepper varieties
68-73.Views:157The aim of our study was to examine susceptibility or resistance of 18 pepper varieties to four viruses [tobacco mosaic
tobamovirus (TMV), sowbane mosaic sobemovirus (SoMV), NTN strain of potato Y potyvirus (PVYNTN) and cucumber mosaic cucumovirus (CMV). Out of the 18 varieties, 13 were resistant to CMV infection. Thirteen varieties were susceptible to TMV, while five ones (Dabora Fl, Brill Fl, Feherozon Synthetic, Ciklon Fl, Cecil Fl) showed only local hypersensitive reaction. All of the tested pepper varieties showed resistance to SoMV. Eight varieties (Tuba, Fehérözön Synthetic, Boni, Alba Regia, Korona, Édesalma, Cecil Fl, Star) were found to be resistant to PVYNTN. Out of the examined varieties five (Boni, Alba Regia, Korona, Édesalma, Star) were resistant to three viruses (SoMV, CMV and PVYNTN). Only one (Cecil F1) displayed complex, extreme resistance to SoMV, PVYNTN, CMV and hypersensitive reaction to TMV, therefore this hybrid is very important in pepper breeding and growing for virus resistance.
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Role of organosilicone surfactant in apple scab control under scab conducive weather conditions
23-25.Views:174Fungicides of integrated fruit production (dithianon, captan, and diclofluanid) and an organosilicone surfactant were compared in spray schedules from green tip until summer in order to control apple scab caused by Venturia inaequalis and to evaluate their phytotoxicity on fruit. Sixteen sprays of 1.8 kg ha-1captan, 0.41 ha-1 dithianon, and 1.8 kg ha-1 diclolfluanid significantly (P=0.05) reduced the incidence of leaf or fruit scab compared to unsprayed products. All fungicides applied with organosilicone at 0.1% resulted in lower incidence of scab on young and older leaves as well as on harvested fruit, but these were not statistically always better than fungicides applied alone. In case of diclofluanid, the fungicide applied with organosilicone at 0.1% resulted in significantly lower (P = 0.001) incidence of scab on young and older leaves. Diclofluanid applied with organosilicone at 0.1% gave the best scab control on leaf and fruit. Treatments applied with fungicides alone had no significant effect on plant phytotoxicity compared to untreated control. All fungicides applied with organosilicone at 0.1% increased (P = 0.05) fruit damage compared to untreated control or fungicide applied alone, though these were not always significantly different. In case of percentage of fruit russet, treatment of dithianon 0.4 1/ha + 0.1% organosilicone significantly increased fruit russet, while fruit russet index significantly increased in the treatment of diclofluanid 1.8 kg/ha + 0.1% organosilicone compared to untreated control. In sum, application of surfactants can help to increase efficacy of scab fungicides; and consequently, to reduce the risk of fungus infection under high scab disease pressure. This fact may also be helpful in fungicide resistance management and reduced-spray programs with accurate scab warning systems.
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Disease warning models for brown rot fungi of fruit crops
19-22.Views:219In this review, disease warning models for brown rot fungi, including Monilinia fructigena, M. laxa and M. fructicola, were summarized. Few studies have been made to relate epidemiology and disease warning in brown rot infection caused by M. fructicola and M. laxa in order to predict infections or develop decision support models for fungicide applications during the growing season. More recently a disease warning model and a decision support system were also performed for M. fructigena for organic apple orchards. This review gives an overview on some details of the above disease warning models and decision support system.
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Comparative study of different fertile groups in plums
71-76.Views:166The plum traditional fruit species in Hungary, several local cultivars was born in the different grower's districts. The author that investigated, that are morphological differences between an odds find self-fertile, self sterile (with functional stamens) and male sterile plum cultivars. For it thought about main questions of a scientific debate sown up and the study this way gave reactions totalize. There were in three fertile groups 8-8 type of feature plum cultivars in periods of 1992-2001, respectively 1993-1999. It was founded by author big odds found the troops on the basis of 9 traits between. Pistil length of self sterile cultivars very typical, such as sesquipedalian flower peduncle of the self-fertile plums and the hypoandry of male sterile cultivars. The relative stamen number and the pollen viability as well significant odds gave.
The average fruit mass and sharka infection of self-fertile plums this troops extreme work. According to cultivar's averages the shark symptoms standard the right correlation the singular traits, but those one part of her with each other not shown connection.
The annuity potencies underdeveloped the troops behind and the troops within cultivar's differences had case significance. The results usable the male sterile cultivars and progeny further its investments.
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Floral biological investigations of apple cultivars in relation to fire blight
9-14.Views:148Floral activity was studied in two apple cultivars: an Erwinia-tolerant (Treedorn') and a sensitive one (`Sampion'). Since more types of protogyny occur in apples, the period of stigma activity is different. Papillae of the exposed stigma in flowers of 'Freedom' function longer (usually more than a week) than in the delayed homogamous `Sampion'. Despite of this, cv. 'Freedom' is tolerant to Erwinia amylovora (Burr.) Winslow et al., suggesting no relationship between the floral biological type (including the exposure and longevity of stigma) and the infection by E. amylovora. According to SEM micrographs, nectary stomata in `Freedom' are already open in the flower bud, where nectar secretion starts and continues until the senescence of the stigma. However, the long period of nectar secretion does not create optimal conditions for bacterial growth, since nectar production is scant in the flowers of 'Freedom'. The surface of the nectary, its nectar-retaining capacity, and the amount and concentration of nectar may influence the susceptibility of apple cultivars. It is manifested well by the smooth nectary surface with nectary stomata rising slightly above the epidermis in flowers of cv. 'Freedom', contrasting the wrinkled, striate nectary surface with slightly sunken stomata in the flowers of 'Sampion'.
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Ascospore dispersal of Venturia inaequalis and subsequent development of scab symptoms in a Hungarian organic apple orchard
35-37.Views:220In this study, we aimed to study ascospore dispersal of Venturia inaequalis and subsequent disease development in an organic apple orchard (Eperjeske) in 2012 and 2013 on apple cultiva ’Mutsu). Burkard spore trap in March and April were used to monitior ascospore concentration and number of scab symptoms were assesed 20 May in both years. Three peaks were detected in ascospore dispersal in the period of examination which was clearly related to the Mills infection periods. On the basis of the incubation period’s length in April (15–18 days), the appearance of first symptoms had direct connection with the peak of the ascospore discharge. The largest number of symptoms were observed on those parts of the orchards where where the inoculum sources were accumulated.
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Susceptibility of sour cherry cultivars to isolates of Monilia laxa (Ehrenbergh) Saccardo et Voglino
83-87.Views:283In this study, the susceptibility of 7 commercially important sour cherry cultivars to Monilinia laxa was studied. Artificial inoculation was made with M. laxa isolates, which were isolated from different woody plants. Artificial inoculation was prepared in the laboratory and in the field. In laboratory, flowers of sour cherries while in the field, the two-year old twigs were inoculated in 2006 and 2007. According to results of stigmata inoculation, there were infection ability differences among the isolates originated from five different stone fruit host. Cultivars could be sorted into two susceptibility groups. In the field, twig inoculation in 2007 was made at blossom period and in 2007 at harvest. Seven sour cherry cultivars were inoculated with 8-day-old mycelial culture of M. laxa originated from sour cherry and almond. The agressivity and pathogenicity of the two isolates were measured by the degree of floem death: Results showed that year and phenological stage considerably influenced the degree of symptoms caused by the fungus. After artificial inoculation, tissue death progression was studied by fluorescent microscope. According to results, sour cherry cultivars were sorted into disease susceptibility groups. Susceptibility orders were identical to results on stigmata inoculation.
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Susceptibility of some traditional pear cultivars of Hungarian and foreign origin to the pathogenic bacterium Erwinia amylovora
41-45.Views:138Fire blight, a disease caused by the bacterium Erwinia amylovora (Burrill) Winslow et al., has been causing serious damage in Hungarian pear plantations since 1996. A prospective control measure could be the use of resistant cultivars. For that purpose ten pear cultivars have been tested under laboratory and greenhouse conditions for resistance to Erwinia amylovora strains collected in Hungary. Six of these cultivars are Hungarian ones of unknown origin, while four are traditional old varieties. Resistant cultivars should serve as germplasm for future breeding. Inoculations were made with a mixture of different pear isolates of the bacteria collected from various growing regions of Hungary (Ea 21, 23), at a density of 5x108 cells/ml. Susceptibility/resistance has been assessed on the basis of intensity of blight symptoms observed on shoots, flower parts and fruits. Cultivars were assigned to three susceptibility groups (low, moderate and high). Complete resistance was not found among the cultivars tested. The highest level of resistance was found in cultivar 'Kieffer', while the other cultivars displayed either moderate or high susceptibility to infection.
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General defense system in the plant kingdom III.
45-54.Views:155Our observations regarding the symptoms not fitting into, significantly differing from the hypersensitive defense system, which we noticed during the judgment of several plant species, symptoms provoked on several million plants have constituted a unified entity. They have provided evidence for the existence of a different plant defense system. We called this so far unknown basic response of plants to biotic effects as general defense system. This system defends them from the attack of numerous microbe species in the environment.
The evolutionary intermediate phase between the general and the specific, the two defense systems is the susceptible host—pathogen relation. The vertical resistance system of plants escaping from the susceptible host—pathogen relation, based on specific hypersensitive reaction also suggested the existence of a more original, general defense system and the susceptible host—pathogen relation developed as a result of the collapse of that system.
The evolutionary relation of the two defense systems is proved by the only recessive inheritance of the older general defense system and in the majority of cases dominant hereditary course of the specific defense system. In our experiences, the modifying genes of the recessive general defense system, in most cases, are behind the specific defense systems, which are known to have monogenic dominant hereditary course and react with hypersensitive tissue destruction. This seemingly striking genetic fact is explained by the following: the general defense system less dependent on environmental effects regulates much faster pathophysiological reaction than the specific resistance genes strongly dependant on environmental effects coding dominant hypersensitive reaction.
The general and specific defense reactions, the processes excluding the microbes attacking plants with compacting of cell growth and tissue destruction, which mean two opposite strategies, building on and regulating each other constitute the entity of resistance to plant disease.
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Analyses of the pathogen and weather components of disease progress for modeling apple scab epidemics in integrated and organic production systems
101-106.Views:164The pathogen and weather components of apple scab disease progress were analysed in a three-year study, in two environmental-friendly production systems (organic and integrated) on cvs. `Idared', `Jonica' and 'Mutsu'. Linear regression analyses of transformed disease incidence and severity data and "area under the disease progress curves" (AUDPC) were used for the analysis of the pathogen component. To evaluate the role of the weather component in apple scab epidemic, first, the weekly disease increase was determined at a certain week (n). Weekly disease increase was related to rainfall, relative humidity, Mills' wetness period, temperature and interaction between temperature and relative humidity. Five different periods were used in the analyses: i) week (n-1), ii) week n(n-1), iii) week (n-2), iv) week (n-1)(n-2) and v) week n(n-1)(n-2). In the analyses of the pathogen component, the best transformation function was the logistic one. Regression analyses showed that disease growth rates were higher for disease incidence and for the organic production system than for disease severity and for the integrated production system, respectively. Disease growth rates for leaf incidence were higher than fruit incidence on all the three cultivars. AUDPC values showed great differences in both leaf and fruit incidences among cultivars and between the two production systems. The results the of analyses of the weather component showed that the best relationships between disease increase and weather parameters were found for fruit incidence and leaf incidence in week (n-2) in the organic and integrated production systems, respectively. Results also demonstrated that in week n(n-1) temperature played a more important role in the fungus development than the water parameters (relative humidity, rainfall and leaf wetness). Consequently, infection process is significantly dependent on almost all weather parameters, but during the incubation period the most important weather parameter is the temperature. Results were compared with similar studies and biological interpretations of the analyses are discussed.
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Industrial-scale plantlet production by seed priming and nursery tray seeding method in Sida hermaphrodita L. Rushby
71-74.Views:198Virginia mallow (Sida hermephrodita Rushby), Malvaceae family, is a perspective perennial herb able to yield a biomass crop through the last two decades. In our previous studies, we examined two factors relating to seed germination percent and seed germination power during our research: the influence of hot water treatment and the effect of exogenous or endogenous infection of seed. Following these recognition we modifi ed our technique, in such a way that we fractionated the seeds based on their fresh weight / or relative density before we carried out the treatment. When we fi ltered the fl oating seeds on the surface of water, the hot water treatment was performed considerably better on the sink seeds after separation. Therefore, by this special priming process we were able to reach 80% germination capacity of Virgina mallow seeds under laboratory conditions (26 oC without illumination). From all nurseries tray methods preliminary results, it is clear that, Sida seeds, which were treated with these methods, gave the best growing rate for industrial uses.
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Investigation on the transmission of some Tobamoviruses by pollen and seed in pepper (Capsicum annuum L.)
127-131.Views:228Five pepper cultivars were mechanically inoculated with isolates of three Tobamovirus species, viz. the "Gelb" strain of tobacco mosaic virus (TMV-G), the XM-isolate of dulcamara yellow fleck virus (DYFV-XM) and the Nov/H isolate of pepper mild mottle virus (PMMV-Nov/H), respectively. Symptoms caused by the viruses were characterised. The viruses were sucessfully re-isolated from different organs (roots, leaves, fruit parts) of susceptible peppers to test plants. It was estabilished, that the pollen of diseased peppers carried infective virions at least on their surface. Washes of seeds were highly infective, but no infectivity was found after treatment of the seeds with 2% NaOH or 10% Na3PO4. No infectivity of inocula prepared from seed-coats of alkaline treated seeds was established. Infection of young seedlings grown from untreated seeds was demonstrated, while the seedlings came from alkaline treated seeds remained free of infective virus. The possible role of pollen and seed in the epidemiology of Tobamoviruses pathogenic to pepper as well as the importance of seed treatment is discussed.
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Effect of Erwinia amylovora infection on peroxidase enzyme activity in resistant apple cultivars
37-39.Views:140Two apple cultivars that display enhanced resistance to fire blight (causal agent: Erwinia amylovora) were selected. The aim of the present study was to characterize the peroxidase (POD) enzyme activity of `Szemes alma' (a historical cultivar) and MR-03, (a Hungarian multiresistant hybrid of 'Prima') and compare them to susceptible 'Jonathan M 40' and resistant 'Remo' controls. Peroxides enzyme activity during E. amylovora infections was investigated in artificially infected apple shoots. Increases in enzyme activities were observed in a `Jonathan M40' and in 'Remo', MR-03, `Szemes alma' cultivars. There was a consistent relationship between total enzyme activity and fire blight disease severity. High activity of the peroxidase was positively correlated with the degree of resistance to fire blight. A general hypothesis that POD activity is related to fire blight susceptibility/resistance is supported by our results.
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Detection of natural infection of Quercus spp. by the chestnut blight fungus (Cryphonectria parasitica) in Hungary
54-56.Views:178The chestnut blight fungus Cryphonectria parasitica (Murrill) Barr [syn.: Endothia parasitica (Murr) Anderson] caused almost total destruction of the American chestnut (Castanea dentata) and widely spread on European chestnut (Castanea saliva) in many European countries. In Hungary, because this fungus threatens most of the Hungarian chestnut stands, great efforts have been made to delay its spread. Biological control with Hungarian hypovirulent strains of the pathogen seems to be an effective method for saving the affected chestnut trees. Until 1998 the fungus was detected on Castanea saliva only, then on some trees of young Quercus petrea in mixed chestnut forests, which also showed the typical symptoms of blight (Kőszeg and Zengővárkony). Although blight symptoms are not so serious in Quercus spp. than in Castanea spp., it seems that C. parasitica threatens the young Quercus spp. in Hungary, mainly in heavily infected chestnut forests. This is the first report of C. parasitica cankers on oak in Hungary.