Electronic Library of Scientific Literature Electronic Library of Scientific Literature
Volume 42 / august 1998 / number 4
H. KEGLER, E. FUCHS, M. GRÜNTZIG, S. SCHWARZ
Bäckerstieg 11, 06449 Aschersleben, Germany;
Martin-Luther-Universität Halle-Wittenberg, Institut für Pflanzenzüchtung
und Pflanzenschutz, Virologie, Halle, Germany
Summary. - Over 300 references on the resistance of stone fruit species to plum pox virus (PPV) have been utilized for the summarization of relevant information in this review. Methods of testing PPV resistance, procedures of evaluation and characterization of PPV resistance as well as breeding of PPV-resistant cultivars are briefly discussed. Altogether 370 cultivars, hybrids and clones of plum, peach, apricot, nectarine and wild Prunus species are tabulated together with the authors who have reported on their immunity, resistance and tolerance.
Key words: plum pox virus; resistance; review
Acta virologica 42: 200 - 215, 1998
H. BAUMGARTNEROVÁ, Ľ. SLOVÁKOVÁ, N. PETRUŠOVÁ
Institute of Experimental Phytopathology and Entomology, Slovak Academy of Sciences, Nádražná 52, 900 28 Ivanka pri Dunaji, Slovak Republic
Summary. - Besides other factors, occurrence of plum pox virus (PPV)-caused spots and mosaic symptoms on leaves of stone fruits are known to influence important physiological functions including production of assimilates. Apricot (Prunus armeniaca L.) seedlings were used as a test material for typical manifestation of symptoms of the disease on the foliage. The relations of the abovementioned visual symptoms to the virus and pigments concentrations in leaves have so far not been known sufficiently. We detected PPV only in symptomatic leaf tissue of the infected apricot. In the green tissue of the same leaves, the double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) of the virus was negative. The content of pigments was changed by PPV infection. In the symptomatic leaf tissues, the content of chlorophylls "a" and "b" was lower, and the content of carotenoids was higher in comparison to the respective controls. We conclude that the PPV infection could cause the change in the content of particular leaf pigments leading to the decreased yield of photosynthesis which in turn could influence the sugar metabolism in the infected trees.
Key words: plum pox virus; apricot; symptomatic leaves; chlorophylls;
carotenoids
Acta virologica 42: 216 - 218, 1998
F. FAGGIOLI, G. PASQUINI, M. BARBA
Istituto Sperimentale per la Patologia Vegetale, Via C.G. Bertero 22, I-00156 Rome, Italy
Summary. - The diagnosis of plum pox virus (PPV) is still considered one of the most important aspects of the "sharka" problem. In fact, different studies demonstrated an uneven distribution of the virus in infected trees due to a high variability in virus concentration. These aspects complicate the PPV diagnosis. To date, biological, serological and molecular assays have been successively developed in order to obtain sensitive and efficient PPV detection techniques. In particular, the polymerase chain reaction (PCR) technique seems to be promising and can be considered the most sensitive and reliable one. Preparation of viral RNA is still a fundamental step in reverse transcription-PCR (RT-PCR) technique, especially when applied to large scale testing, i.e., for certification purposes. In order to find the most rapid and efficient procedure, we have compared three different procedures of extraction of viral RNA to be processed RT-PCR. Their common characteristics is their capacity to extract the RNA from a small amount of plant tissue without organic solvents in the extraction fluid. The procedures were as follows: an immuno-capture (IC) method using a specific antiserum, a silica-capture (SC) method using a non-specific matrix, and a simple and rapid RNA extraction (RE) method. They all were followed by one-tube RT-PCR. The obtained results show that all the three techniques allowed a successful amplification and detection of PPV in tested samples except the SC-PCR method which proved less effective. In fact, the IC-PCR and RE-PCR methods amplified and detected PPV in all isolates tested, while the SC-PCR method was able to reveal the presence of the virus in apricot and infected control samples only.
Key words: plum pox virus; diagnosis; reverse transcription-polymerase
chain reaction
Acta virologica 42: 219 - 221, 1998
E. FUCHS, M. GRÜNTZIG, H. KEGLER
Martin-Luther-University Halle-Wittenberg, Institute of Plant Breeding
and Plant Protection, Emil-Abderhalden-Str. 27, 06108 Halle (Saale), Germany;
Bäckerstieg 11, 06449 Aschersleben, Germany
Summary. - In our three-year investigation, 164 apricot trees of different old German varieties cultivated in the Mansfelder Land region were tested for the plum pox virus (PPV) resistance by double grafting in greenhouse conditions using an isolate of PPV D strain from our region. We selected 25 genotypes with quantitative resistance and two with immunity. The first results of field trials are comparable with those from greenhouse. With cvs. Virosia and Brevira, two local quantitatively resistant varieties will be available from autumn 1998. The origin of both trees, which were found to be immune, is still unclear. They will be used for propagation only after the variety identification.
Key words: plum pox virus; apricot; German cultivars; Virosia;
Brevira; Mansfelder Land region; quantitative resistance; immunity
Acta virologica 42: 222 - 225, 1998
M. GLASA, J. MATISOVÁ, O. KÚDELA
Institute of Virology, Slovak Academy of Sciences, Dúbravská cesta 9, 842 46 Bratislava, Slovak Republic
Summary. - Plum pox virus (PPV) isolates from stone-fruit trees (plums, myrobalans, apricots and peaches) from orchards and gardens were characterized. To characterize their biological properties, several PPV isolates were transmitted by chip budding to GF 305 seedlings and mechanically to selected herbaceous test plants. The isolates differed in severity of infection, host range and symptomatology. A subgroup differentiation of 43 isolates from 22 localities of western and middle Slovakia was accomplished using reverse transcription-polymerase chain reaction (RT-PCR), immunocapture RT-PCR (IC-RT-PCR) and restriction analysis. These assays confirmed the presence of isolates belonging to PPV-M and PPV-D subgroups. PPV-M and PPV-D isolates were almost equally represented in tested samples. Tests of subgroup variability of PPV isolates from infected tolerant plum cultivars showed great predominance of PPV-M isolates.
Key words: plum pox virus isolates; enzyme-linked immunosorbent
assay; polymerase chain reaction; restriction analysis; tolerant plum cultivars
Acta virologica 42: 226 - 229, 1998
W. HARTMANN
Institut für Obst-, Gemüse- und Weinbau (370), Universität Hohenheim, 70593 Stuttgart, Germany
Summary. - At Hohenheim we started a plum breeding programme to get new sharka-resistant cultivars with better fruit quality. In the last years we have recognized that the resistance of all cultivated plums is based on quantitative criteria and therefore relative. For this reason we changed our strategy for the resistance breeding. For the first breeding cycle we used special donors with quantitative resistance. Today, the qualitative resistance is more integrated. We intend to combine both types of resistance in the hexaploid genome of Prunus domestica to obtain an absolute and durable resistance. To achieve this aim, we have to consider the evaluation of resistance, the genetic resources, the inheritance of the resistance and also the breeding methods. The results of our resistance breeding study are presented.
Key words: plum; breeding; sharka; quantitative and qualitative
resistance
Acta virologica 42: 230 - 232, 1998
M. ISAC, S. PREDA, M. MARCU
Research Institute for Pomology, Pitesti-Maracineni, Romania;
Research Station for Pomology, Valcea, Romania;
Research Station for Pomology, Geoagiu, Romania
Summary. - Plum pox virus (PPV) is widely spread by natural vectors present in plum orchards. The efficiency of transmission is dependent on the frequency of the occurrence of vectors and the cultivar susceptibility to this pathogen. Having in view that PPV has a wide range of annual and multiannual host plants and vectors, there is great concern for obtaining PPV-resistant cultivars. This report deals with the following vectors: Hyalopterus pruni, Brachycaudus cardui, Brachycaudus helichrysi, Myzus persicae and Phorodon humuli aphids, and Aculus fockeni mite. Seven different cultivars of Prunus domestica were utilized. To assess the virus transmission rate, 50 - 100 individual vectors per tree were used. The treatment of the trees was performed every four weeks and then the disease symptoms were observed. PPV was transmitted by all vectors studied, the rate ranging in dependence on the susceptibility of cultivars used. Thus, in cvs. Centenar, Pescarus, d'Agen, Stanley and Tuleu Gras, the transmission rate ranged from 20% to 60%, while in susceptible cvs. Vanat romanesc and Vanat de Italia - from 40% to 80%
Key words: plum pox virus; plum cultivars; vectors
Acta virologica 42: 233 - 234, 1998
C. JACQUET, M. RAVELONANDRO, J. DUNEZ
Station de Pathologie Vegetale, INRA Bordeaux, BP 81, 33883 Villenave d'Ornon, France
Summary. - Transgenic plums transformed with the plum pox virus coat protein (PPV CP) gene displayed a resistance to the sharka disease (Ravelonandro et al., 1997). However, the expression of PPV CP in transgenic plants may lead to complementation of deficient characteristic of an incoming potyvirus. Indeed, an aphid-intransmissible strain of zucchini yellow mosaic virus (ZYMV-NAT) could be transmitted when encapsidated by the engineered PPV CP (Lecoq et al., 1993). To control such a risk, new PPV CP constructs were designed and introduced into Nicotiana benthamiana genome. In the first construct, the DAG amino acid triplet involved in the potyvirus aphid-transmission was deleted. The second construct encoded a truncated PPV CP lacking its first 140 amino acids. In the last construct, the nucleotides encoding the charged amino-acids R220, Q221 and D264 localized in the core of the PPV CP were removed. A bacterial expression system was developed to show that these deletions prevent the assembly of the PPV CP subunits. For each construct, several transgenic lines were produced and first challenged with several strains of PPV. Two phenotypes of resistance were observed: recovery and immunity. Their biochemical characterization showed that the resistance was RNA-mediated and therefore can be classified as homology-dependent (Jacquet et al., 1998a). Resistant lines producing high level of wild type or modified PPV CP were then inoculated with ZYMV-NAT to perform an aphid-transmission assay. Results of these experiments demonstrated that the use of modified forms of PPV CP genes in transgenic plants provide a good way to control the biological risks associated with heteroencapsidation (Jacquet et al., 1998b).
Key words: plum pox virus; coat protein; transgenic plants; biological
risks
Acta virologica 42: 235 - 237, 1998
J. KRÁĽOVIČ, V. KRÁLOVÁ
Institute of Experimental Phytopathology and Entomology, Slovak Academy of Siences, Nádražná 52, 900 28 Ivanka pri Dunaji, Slovak Republic
Summary. - The experimental results obtained from a fruit garden at Krajné pointed out a different content of macrobiogenic elements in the leaves of plum trees infected with plum pox virus (PPV) as compared to healthy ones. Mineral nutrition of diseased trees was characteristic by lower relational values of topical levels of macrobiogenic elements especially those of N/P, N/K, (Ca + Mg)/K, and (N/P)/(N/K).
Key words: plum tree; plum pox virus disease; nitrogen; phosphorus;
potassium; calcium; magnesium
Acta virologica 42: 238 - 240, 1998
T. MALINOWSKI, B. ZAWADZKA, M. RAVELONANDRO, R. SCORZA
Research Institute of Pomology and Floriculture, Pomologiczna 18, 96-100 Skierniewice, Poland; Station de Pathologie Vegetale, INRA Bordeaux, Villenave d'Ornon, France; USDA-ARS Appalachian Fruit Research Station, Kearneysville, WV, USA
Summary. - Five transgenic clones of Prunus domestica L. containing plum pox virus (PPV) coat protein (CP) gene and one non-transformed control clone were challenged with PPV-S in the field. Symptoms developed on C2, C3, C4, C6 and B70146 but not C5 trees inoculated by chip budding (CBI) (2/2, 2/2, 1/1, 2/2 and 2/2, positive/inoculated) in the first summer after inoculation. However, in the second year, symptoms appeared on CBI C5 trees. The presence of the virus in the plants was confirmed by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) amplification of a fragment of viral polymerase gene. During two years, symptoms of infection developed on 3 to 4 of 8 non-inoculated trees of clones C2, C3, C4, C6 and B70146. Eight non-inoculated C5 trees remained symptomless and ELISA-negative as of spring 1998, in spite of the presence of aphid vectors and inoculum sources.
Key words: plum pox virus; transgenic plum; resistance
Acta virologica 42: 241 - 243, 1998
N. MINOIU, A. MAXIM, D. VLADIANU, I. PLATON, R. BALACI
Fruit Research Station, 4400 Bistrita, Romania
Summary. - Our recent results on the plum pox virus (PPV) epidemiology show that PPV spreads very rapidly in plum tree plantations in the contaminated areas. A clearing of the PPV-infected trees reduces significantly the spread of the virus but does not eliminate the disease. Some plum tree cultivars, hybrids and rootstocks (Scoldus, Alina, Cristi, BN 1/8Fl, BN 2Gr. etc) showing field resistance could not be infected with PPV by natural way. However, they could be infected with PPV by artificial inoculation except for the plum tree cv. Local of Dragasani and the BN 4Kr myrobalan, which proved to be immune to PPV. PPV was not transmitted through seeds in plum tree and myrobalan in the nursery. The Hyalopterus pruni aphids were found PPV-positive by an enzyme-linked immunosorbent assay (ELISA).
Key words: plum pox virus; enzyme-linked immunosorbent assay;
epidemiology
Acta virologica 42: 244 - 247, 1998
A. MYRTA, O. POTERE, D. BOSCIA, T. CANDRESSE, M. CAMBRA, V. SAVINO
Dipartimento di Protezione delle Piante dalle Malattie, Universita
degli Studi and Centro di Studio del CNR sui Virus e le Virosi delle Colture
Mediterranee, Bari, Via Amendola 165/A, I-70126, Italy;
Station de Pathologie Végétale, INRA, Villenave d'Ornon, France;
Instituto Valenciano de Investigaciones Agrarias Moncada, Valencia, Spain
Summary. - Plum pox virus (PPV) isolates are grouped into three clusters differentiated by biological, serological, molecular and epidemiological characteristics: Marcus (M), Dideron (D) and Cherry (C). The El Amar (EA) isolate that does not fit any of the above groups is also known. Monoclonal antibodies (MAbs) that specifically recognize M, D, and C strains of PPV are already available. To complete the set of PPV strain-specific serological reagents, MAbs against the EA isolate were raised by immunizing BALB/c mice and fusing their spleen cells with NS0/1 myeloma cells. After a preliminary characterization by double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), 1 of 13 selected MAbs proved to be EA strain-specific. This MAb (EA24) reacted equally well with a homologous antigen and several PPV isolates from Egyptian apricot trees, supporting the hypothesis of an additional specific PPV group. MAb EA24 did not react either with about a hundred PPV isolates belonging to the D and M groups or with PPV-SwC and PPV-SoC isolates belonging to the C group. The strain specificity of MAb EA24 was confirmed by Western blot analysis and immunoelectron microscopy. We conclude that there is now available a set of MAbs which are highly specific to the four currently known groups of PPV strains.
Key words: plum pox virus; El Amar strain; monoclonal antibodies;
Western blot analysis
Acta virologica 42: 248 - 250, 1998
A. MYRTA, B. DI TERLIZZI, D. BOSCIA, K. ÇAGLAYAN, I. GAVRIEL, G. GHANEM, C. VARVERI, V. SAVINO
Ministry of Agriculture and Food, Tirana, Albania;
Istituto Agronomico Mediterraneo, Via Ceglie 9, 700 10 Valenzano, (BA),
Italy;
Dipartimento di Protezione delle Piante dalle Malattie, Universitá Centro
di Studio del CNR sui Virus e le Virosi delle Colture Mediterranee, Bari,
Italy;
Plant Protection Department, Mustafa Kemal University, Antakya, Turkey;
Department of Agriculture, Plant Protection Section, Nicosia, Cyprus;
Plant Pathology Department, Cairo University, Giza, Egypt;
Benaki Phytopathological Institute, Athens, Greece
Summary. - Plum pox virus (PPV) is a major threat to the expanding Mediterranean stone fruit industry. In order to control the plum pox disease it is of utmost importance to detect early PPV foci and to identify the PPV isolates involved. A survey was therefore carried out in Albania, Cyprus, Egypt, Greece, Italy and Turkey by a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with the following monoclonal antibodies (MAbs): 5B (universal), 4DG5 (PPV-D-specific), AL (PPV-M-specific), TUV and AC (PPV-C-specific), and EA24 (PPV-El Amar-specific). A hundred and seventy Mediterranean PPV isolates were tested for strain type. PPV-M was detected in Albania, Cyprus, Greece, Italy, and Turkey; PPV-D was detected in Albania and Italy, whereas samples with natural mixtures of both strains were found in a couple of orchards in Albania. Seven PPV isolates from apricots in two Egyptian localities were recognized only by MAb EA24. In conclusion, DAS-ELISA with a combination of the universal MAb5B and the MAbs specific to the four PPV serotypes currently known (M, D, C and El Amar) is an efficient tool for a simple, sensitive and routine detection of PPV and discrimination of its serotypes.
Key words: plum pox virus; Mediterranean isolates; monoclonal
antibodies; enzyme-linked immunosorbent assay
Acta virologica 42: 251 - 253, 1998
M. NAVRÁTIL, V. ŠIMONOVÁ, R. FIALOVÁ, P. VÁLOVÁ
Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Šlachtitelů 11, 783 71 Olomouc, Czech Republic
Summary. - Seventy-two Czech plum pox virus (PPV) isolates from different hosts were tested by double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). In addition, the coat protein mobility and the RsaI restriction fragment length polymorphism (RFLP) pattern of reverse transcription-polymerase chain reaction- (RT-PCR) amplified coat protein (CP) gene fragment of the isolates were analysed. Both PPV-D and PPV-M serotypes were found in the Czech Republic. The results obtained by these different methods were in accord with exception of a few cases probably caused by mutation or recombination.
Key words: plum pox virus; coat protein; enzyme-linked immunosorbent
assay; Western blot analysis; reverse transcription; polymerase chain reaction;
restriction fragment length polymorphism
Acta virologica 42: 254 - 256, 1998
F. PAPRŠTEIN, R. KAREŠOVÁ
Research and Breeding Institute of Pomology, 507 51 Holovousy, Czech Republic
Summary. - A long-term orchard experiment with a broad assortment of plum cultivars aimed to screen their sensitivity to plum pox virus (PPV) was established in 1991. For this purpose, 207 cultivars to be artificially infected with PPV at a permanent site were chosen. The serotype M of PPV from a tree of cv. Domestic Prune, which had not been contaminated by other viruses, was used as a source of the infection. Three buds infected with PPV were budded on 1-year-old trees. In the course of the experiment the following results were obtained. The highest transmission of PPV was recorded in the first year after infection, when 69.5% of positive trees were detected by enzyme-linked immunosorbent assay (ELISA). After 4 years, the absence of PPV was still detected in 11.2% of the cultivars. These were reinfected with the same source of PPV in 1996. In 1998, there were 92.9% of trees contaminated by sharka. Seven years after infection with PPV, a dieback of 41 trees took place. In the most cases a presence of an ilarvirus in the plant was detected. The PPV infection was not transferred further on cvs Bila trnecka, Francia Naranes, Large Sugar Prune, Reine Claude Diaphane, Renkloda Jandacek, Scoldus, Tarnina x Kirke, Valasska trnecka and K-4. There were 75% of trees fruited in 1997. Only 28 cultivars had no symptoms of PPV on fruits. A statistically significant relationship between the incidence of PPV after the artificial infection and a the presence of prunus necrotic ring spot virus (PNRSV). The presence of PNRSV reduced the transmission of PPV. Relationships between PPV and prune dwarf virus (PDV), and between PPV and (PDV + PNRSV) were not statistically significant.
Key words: plum pox virus; plum cultivars; germplasm; tolerance
Acta virologica 42: 257 - 259, 1998
G. PASQUINI, A.M. SIMEONE, L. CONTE, M. BARBA
Istituto Sperimentale per la Patologia Vegetale, Via C.G. Bertero 22,
001 56 Rome, Italy;
Istituto Sperimentale per la Frutticoltura, Rome, Italy
Summary. - Twelve different apricot selection trees from a germplasm collection naturally infected with plum pox virus (PPV) were chosen to investigate the role of seeds in the epidemiology of this dangerous pathogen. All the considered plants showed typical symptoms on leaves and fruits and were positive in enzyme-linked immunosorbent assay (ELISA). The virus was characterized by immunocapture reverse transcription-polymerase chain reaction (IC-RT-PCR) followed by restriction fragment length polymorphism (RFLP) analysis with RsaI enzyme as a PPV-D isolate. The presence of PPV was checked on fully ripe seeds and seedlings. One half of the seed stock was analysed immediately by ELISA and IC-RT-PCR tests: the cotyledons containing also the embryo were separated from the teguments. The other half of the seed stock was germinated and maintained in an insect-proof screenhouse over a 2-year period. PPV was detected by ELISA only in the seed coat while by IC-RT-PCR also in cotyledons. Seedlings from infected seeds did not show any typical symptoms and were PPV-negative in serological and molecular assays. So far, the presence of PPV in seeds seems to play no role in its epidemiology.
Key words: plum pox virus; seed transmission; enzyme-linked immunosorbent
assay; reverse transcription; polymerase chain reaction
Acta virologica 42: 260 - 263, 1998
J. POLÁK
Research Institute of Crop Production, Division of Phytomedicine, Drnovská 507, 161 06 Prague, Czech Republic
Summary. - The relative concentration of plum pox virus (PPV) in leaves and flowers of plum, damson, myrobalan, blackthorn, apricot and peach trees was determined by enzyme-linked immunosorbent assay (ELISA) and expressed as the lowest dilution with positive reaction. Significant differences in relative PPV concentration were found in leaves among individual Prunus species naturally or artificially infected with the virus. The highest relative PPV concentration was found in blackthorns (7.81 x 10-4), common plum and apricot (1.56 x 10-3 for the both latters). Wild growing PPV-infected plums and blackthorns can be considered equally important source of sharka infection as PPV-susceptible cultivars of plums, apricots and peaches. High PPV concentration in flowers is of diagnostical value. High variability of relative PPV concentration was observed inside the species among individual cultivars. Susceptible cultivars were characteristic by high relative PPV concentration, e.g. apricot cvs. Vegama (9.8 x 10-5) and Velkopavlovická (1.95 x 10-4), and peach cvs. Maria Emilia (7.81 x 10-4) and Harbinger (1.56 x 10-3). On the other hand, cultivars resistant to PPV were characteristic by very low relative PPV concentration, e.g. apricot cv. Stark Early Orange (5 x 10-2) and peach cvs. Envoy (5 x 10-2) and Favorita Morettini (2.5 x 10-2). The highest relative PPV concentration was found in young trees newly infected with PPV.
Key words: plum pox virus; common plum; damson; myrobalan; blackthorn;
apricot; peach; enzyme-linked immunosorbent assay; relative virus concentration;
leaves; flowers
Acta virologica 42: 264 - 267, 1998
Z. PONCAROVÁ, P. KOMÍNEK
Research Institute of Crop Production, Drnovská 507, 161 06 Prague, Czech Republic
Summary. - Reverse transcription-polymerase chain reaction (RT-PCR) technique and restriction fragment length polymorphism (RFLP) analysis were used to analyse six isolates of plum pox virus (PPV). Whole coat protein (CP) gene was amplified in four isolates using the unipoty-polyT primer pair. PPV-D was identified by RFLP analysis using SfuI and DraI enzymes in two of the isolates. Two isolates of PPV-M strain yielded RT-PCR products which could not be digested by the two enzymes. Other isolates were subjected to RT-PCR using P1-P2 primers. The specificity of the RT-PCR products was confirmed by AluI digestion, while RsaI digestion enabled strain differentiation. No mixed infection was found.
Key words: plum pox virus; PPV-D strain; PPV-M strain; coat protein;
restriction fragment length polymorphism; reverse transcription; polymerase
chain reaction
Acta virologica 42: 268 - 269, 1998
M. RAVELONANDRO, R. SCORZA, J. DUNEZ
Station de Pathologie Vegetale, INRA Bordeaux, BP 81, 33883 Villenave
d'Ornon, France;
USDA-ARS Appallachian Fruit Research Station, Kearnsville, WV, USA
Summary. - Resistance to plum pox virus (PPV) infection can be obtained in transgenic plants that express the virus capsid gene. An Agrobacterium-mediated transformation was used to introduce the PPV capsid gene into Prunus domestica plants. Over 11 regenerated plants (clones) were observed for the development of the disease symptoms and analysed for the presence of PPV by enzyme-linked immunosorbent assay (ELISA), Western blot analysis, and reverse transcription-polymerase chain reaction (RT-PCR) through 4 dormancy cycles. The level of protection against PPV was determined in the transformed plants, non-transformed plants, and a control transgenic plant "transformed" with the plasmid vector alone. One clone, C-5, appeared fully protected, while PT-6 and C-4 clones accumulated a low concentration of virus and the rest of the clones was entirely susceptible. Little is known about the mechanisms of resistance to virus infection in transgenic woody plants. To investigate this aspect, comparative studies based on the characteristics of resistant and susceptible clones have been started. A question, whether the phenotype resistance of clone C-5 is similar to that observed in transgenic herbaceous plants or not, has been addressed. Recent progress in this investigation is presented.
Key words: plum pox virus; capsid gene; expression; phenotype
resistance
Acta virologica 42: 270 - 272, 1998
F. ŠPÁNIK, I. HRIČOVSKÝ, B. ŠIŠKA
Department of Biometeorology and Hydrology, Slovak Agricultural University, Mariánska 10, 949 01 Nitra, Slovak Republic
Summary. - In this report, the plum pox virus (PPV) spread from the point of view of agroclimatical conditions on the territory of Slovakia is analysed. The worst condition for the PPV spread was found in a warm macroregion. The air temperature sum in this macroregion during vegetative period ranged from 2400 to 3100°C. The worst condition for the PPV spread was found in dry subregions of the macroregion. These were defined by differences between potential evapotranspiration and rainfall sums which ranged from 50 to 150 mm during summer months (from June to August). The decrease in air temperature sums and the increase of moisture in the environment as well as the severity of winter period was found to support the occurrence and spread of PPV.
Key words: plum pox virus; spread; climatical conditions
Acta virologica 42: 273 - 275, 1998
S. TOMA, M. ISAC, V. BALAN, A. IVASCU
Research Station for Fruit Tree Growing Baneasa, Bucharest, Romania;
Research Institute for Fruit Growing, Pitesti-Maracineni 0300, Romania
Summary. - Plum pox virus (PPV) is a potyvirus widely spread in many species of the Prunus genus such as plum, apricot, peach, sweet cherry and others.This potyvirus causes great damage to stone fruit trees in Romania and other European countries as Hungary, Italy, Czech Republic, France, Spain, Greece, Turkey, and Slovak Republic. The Research Station for Fruit Tree Growing Baneasa in Bucharest has realized many studies on the epidemiology and spread of PPV and also on the disease symptomatology and detection possibilities. The control of sharka disease by sanitary selection measures requires corresponding detection techniques. The aim of this study was to determine the presence or absence of PPV in some apricot and peach varieties and hybrids in 1995-1997 by the enzyme-linked immunosorbent assay (ELISA) and to verify if some of our biological materials evaluated as symptom-free under field conditions for many years are also virus-free and can be considered healthy.
Key words: plum pox virus; enzyme-linked immunosorbent assay;
apricot; peach; nectarine
Acta virologica 42: 276 - 277, 1998