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1.
Kazuya Ishikawa Kensaku Maejima Susumu Nagashima Nobuo Sawamura Yusuke Takinami Ken Komatsu Masayoshi Hashimoto Yasuyuki Yamaji Jun Yamamoto Shigetou Namba 《Journal of General Plant Pathology》2012,78(2):136-139
For the first time, fig mosaic virus (FMV) was detected in common fig (Ficus carica) trees in Shimane, Japan. These trees exhibited mosaic, ringspots, or distortion, accompanied by chlorosis on leaves and
yellow spots on fruits. Some of the symptomatic trees were infested with the eriophyid mite Aceria ficus. The virus was detected based on RT-PCR, followed by sequencing. The amplified 300 base-pair fragments shared 83.5–91.5%
identity with the corresponding region of RNA-dependent RNA polymerase gene of FMV isolates previously reported in Turkey,
Iran, and Italy. 相似文献
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Kazuya Nakamura Noriko Yamagishi Masamichi Isogai Sadao Komori Tsutae Ito Nobuyuki Yoshikawa 《Journal of General Plant Pathology》2011,77(1):48-53
To examine whether Apple latent spherical virus (ALSV) has spread among apple trees in an orchard, we surveyed 21 apple trees surrounding two ALSV-infected trees for virus
infection using a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). None of the 21 trees were infected,
indicating that ALSV has not spread from the infected trees to the neighboring apple trees since it was first detected in
1984. We analyzed seed embryos and seedlings derived from infected trees and detected ALSV in 10 of 223 seed embryos (4.5%)
and 10 of 227 seedlings (4.4%). From these results, we conclude that ALSV is seed-transmitted at a rate of ca. 4.5% in apple.
We also analyzed seed embryos and seedlings from uninfected apple trees that were hand-pollinated with pollen from infected
trees. We detected ALSV in only 1 of 260 seed embryos and in none of the 227 apple seedlings. This result indicated that the
seed transmission rate via infected pollen is only 0–0.38%. In situ hybridization analysis of ALSV-infected apple flower buds
showed that ALSV was present inside almost all pollen grains and in all ovary and ovule tissues, including the embryo sac
and inner integument. 相似文献
4.
Silvio Aparecido Lopes Guilherme Fernando Frare Pedro Takao Yamamoto Antonio Juliano Ayres José Carlos Barbosa 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(4):463-468
The huanglongbing (HLB) disease of citrus trees, caused by Candidatus Liberibacter asiaticus and Ca. Liberibacter americanus, was first reported in Brazil in March, 2004. The presence of the disease has caused serious concerns
among growers. Pruning experiments were conducted to determine if removal of symptomatic branches or the entire canopy (decapitation)
would eliminate infected tissues and save HLB-affected trees. Pruning was done in five blocks on a total of 592 3- to 16 year-old
‘Valência’, ‘Hamlin’ or ‘Pêra’ sweet orange trees showing no symptoms or with two levels of symptom severity. Ten decapitated
trees per block were caged and all trees were treated with insecticides to control the psyllid vector, Diaphorina citri. Mottled leaves reappeared on most symptomatic (69.2%) as well on some asymptomatic (7.6%) pruned trees, regardless of age,
variety, and pruning procedure. Presence of the pathogen (Ca. Liberibacter americanus) in all symptomatic trees was confirmed by PCR. In general, the greater the symptom severity before
pruning the lower the percentage of trees that remained asymptomatic after pruning. 相似文献
5.
Apple mosaic virus (ApMV, genus Ilarvirus) was detected in pears, a previously non-reported virus host. No symptoms were visible on the hosts leaves. Seventeen out of 22 randomly selected pear trees in Italy (Lombardy) and in three regions in the Czech Republic were ApMV-infected. All nine newly sequenced ApMV isolates from pears had a 15-nucleotide insertion in the capsid protein gene in identical position of that of apple isolates compared with isolates from hop and prunes. The insertion is the most prominent (but not essential) modification of the capsid protein gene, which results in a phylogenetic separation of ApMV isolates into three clusters. Sequence analysis data of an additional 15 isolates revealed a sequence correlation with kernelled fruit trees (apple and pear). 相似文献
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Carla M. R. Varanda Marta S. M. R. Silva Maria do Rosário F. Félix Maria Ivone E. Clara 《European journal of plant pathology / European Foundation for Plant Pathology》2011,130(2):165-172
Transmission of three strains of OMMV by an Olpidium sp. was evaluated and compared. The three strains were 1) an OMMV wild type (WT) recovered from olive trees, 2) an OMMV variant
(L11) obtained after 15 serial passages of single local lesions induced in Chenopodium murale plants, and 3) a construct OMMV/OMMVL11 in which the coat protein (CP) gene replaced that of the wild type. A single-sporangial
culture derived from Chinese cabbage (Brassica pekinensis) used as a bait plant grown in soil of an olive orchard, was identified as Olpidium brassicae based on the size and sequence of the generated amplicon in PCR specific tests. Each of the three virus strains was soil
transmitted to cabbage roots in the absence of the fungus at similar rates of 30 to 40%. Separate plant inoculation by O. brassicae zoospores incubated with each viral strain resulted in enhanced transmission of OMMV, reaching 86% of infection whereas that
of the other two strains remained practically unaffected at ca. 34%. Binding assays showed that the amount of virus bound to zoospores, estimated spectrophotometrically, was 7% in the
case of OMMV, and practically nil in the case of the other two viral strains. Substitution of the coat protein (CP) gene of
OMMV by that of the OMMV L11 strain, drastically reduced viral transmissibility in the presence of zoospores to the level
of that observed in their absence. Our data shows that OMMV soil transmission is greatly enhanced by O. brassicae zoospores and that the viral CP plays a significant role in this process, most likely by facilitating virus binding and later
entrance into the host plant roots. 相似文献
8.
Joseph Aubert Mouen Bedimo Daniel Bieysse Ibrahim Njiayouom Jean Pierre Deumeni Christian Cilas Jean Loup Nottéghem 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(4):391-400
In the high altitude regions of Africa, coffee berry disease (CBD), caused by Colletotrichum kahawae, is the main constraint for arabica coffee (Coffea arabica) production. However, certain agricultural practices can reduce losses caused by the disease and thereby promote optimum
production. On small family farms in Cameroon, mixed cropping with fruit trees, intercropping with food crops and maintenance
pruning of coffee trees are very widespread agricultural practices that can affect CBD epidemics. Consequently, an epidemiological
study was conducted to assess how cultural practices affected the disease in an arabica coffee smallholding in Cameroon. The
disease was monitored on a weekly basis over four successive years (2002–2005) on coffee trees in diverse cultural situations.
Cultural practices likely to reduce losses due to CBD were identified. The infection rate was significantly lower on coffee
trees grown intensively than on coffee trees grown in the traditional manner. Coffee trees located under the shade of fruit
trees were significantly less attacked than those located in full sunlight. In addition, berries on the leafless parts of
branches, near the main trunk of the coffee tree, were less infected than those on leafy sections. These results show that
maintenance pruning, removal of mummified berries, and mixed cropping with shade plants are cultural practices which create
environmental conditions that limit CBD development. 相似文献
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Prunus stem pitting disease was first described and recognized as a specific, infectious disease in 1967 and is now known to affect a number of Prunus species. Apricot trees affected by stem pitting show stunted terminal growth and chlorotic, drooping leaves that curl upward and lengthwise. The lower trunk may become enlarged at ground level or below with very thick, spongy bark. Removal of the bark from the affected lower trunk reveals pits and grooves on the woody cylinder. Wood pitting begins below ground, then gradually spreads into the roots and the trunk above ground. Stem pitting is caused by certain strains of the tomato ringspot virus. The causal agent is soil-borne and also graft transmissible but is not uniformly distributed through infected trees. Naturally infected apricot trees may show a slow decline, or rapid dieback of the terminal growth. The severity of symptoms is determined by the cultivar and the strain of tomato ringspot virus. Control measures for Prunus stem pitting should include: use of propagation material from healthy trees and rogueing of pitted trees in nurseries and orchards. Repeated use of infested nursery sites for stone fruit nurseries should be avoided 相似文献
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Carla Varanda Joana M. S. Cardoso Maria do Rosário Félix Solange Oliveira Maria Ivone Clara 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(2):161-164
An optimized multiplex RT-PCR assay was developed to discriminate three necrovirus (Olive latent virus 1 (OLV-1), Tobacco necrosis virus D (TNV-D) and Olive mild mosaic virus (OMMV)) that infect olive trees. An olive orchard consisting of 54 trees of cv. “Galega vulgar” in the south of Portugal
was surveyed. dsRNA fraction was used as template and revealed the 3 viruses, singly or in multiple infections, present in
17 out of 54 trees in the orchard. OMMV was the most frequent occurring in 15 trees, followed by OLV-1 in 12 and TNV-D in
4 plants. The results obtained showed that necrovirus- specific dsRNAs do exist in infected tissues in amounts below the resolution
permitted by gel electrophoresis analysis and that the developed multiplex PCR based assay is of much higher sensitivity.
The design of the specific primers described enabled, for the first time, to discriminate between OMMV and TNV-D by means
of RT-PCR assays, an indispensable tool in identification, epidemiology and survey studies. 相似文献
13.
Molecular and biological characterization of Potato mop‐top virus (PMTV,Pomovirus) isolates from the potato‐growing regions of Colombia
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Potato mop‐top virus (PMTV) causes necrotic flecks inside and on tubers in temperate countries. In South America, these symptoms have not been observed, although the presence of the virus has been confirmed in the Andes and in Central America. To characterize PMTV isolates from the Andes, soil samples were taken from the main potato‐producing regions in Colombia and virus was recovered by planting Nicotiana benthamiana as bait plants. The complete genomes of five isolates were sequenced and three of the isolates were inoculated to four different indicator plants. Based on sequence comparisons, three types of RNA‐CP (RNA2) and RNA‐TGB (RNA3) were found. The isolates from the centre of the country (CO3 and CO4) were similar to isolates from Europe. The genomes of CO1, CO2 and CO5 differ from other PMTV isolates, placing them in a separate clade in phylogenetic trees. The three Colombian isolates (CO1, CO2 and CO5) only induced slightly different symptoms in the indicator plants. However, the isolate from the northwest of the country (CO1) induced stronger symptoms in N. benthamiana including severe stunting. A correlation between the genotype of the isolates and the symptoms they induced on indicator plants was not found. 相似文献
14.
Naoki Eguchi Hirofumi Tokutake Naho Yamagishi 《Journal of General Plant Pathology》2008,74(5):382-389
Hot water was dripped into the rhizosphere of Japanese pear trees (Pyrus serotina Rehd. grafted on P. betulifolia Bunge.) infested with the white root rot fungus Rosellinia necatrix Prillieux, to destroy the fungus. Isolates of R. necatrix from diseased roots of Japanese pear were vulnerable to water at temperatures above 35°C, and the fungus was eradicated from
the colonized substrate when water at 35°C was provided for 3 days. The time required to eradicate R. necatrix decreased exponentially with increasing temperature. Japanese pear trees tolerated a temperature of 45°C without reduction
in vigor. Field experiments demonstrated the practical use of hot water drip irrigation (HWD). HWD at 50°C completely destroyed
white root rot mycelia on diseased roots, and many rootlets grew after the treatment. HWD at this temperature caused no injury
to the trees. HWD of diseased orchard trees was assessed in Takamori and Iida in southern Nagano, Japan. The fungus recurred
in two of four trees 28 months after treatment in Takamori and in two of ten trees 16 months after treatment in Iida. The
new mycelia emerged on thick roots deep within the soil. Although there is a possibility of recurrence, HWD treatment is a
practical control measure for white root rot. 相似文献
15.
Natural recovery from wilt disease symptoms was evaluated in young olive trees root dip inoculated with Verticillium dahliae in a growth chamber over a 12 week period and, later on, when the trees were transplanted in a V. dahliae-free soil in a lathhouse during a period of 127 weeks. Recovery in an individual tree was considered when a plant showed
symptom remission after having reached a maximum value of symptom severity. Recovery accounted for 53% of 464 trees that showed
wilt symptoms during observations in the two environments. The remaining trees died. Recurrent wilt symptoms were not observed
in recovered trees, and recovery was usually accompanied by the production of new green tissues. Recovery was clearly higher
in trees inoculated with a non-defoliating (ND) isolate (86.4%) of the pathogen than in those inoculated with a defoliating
(D) isolate (23.9%). The percentage of recovery and the level of resistance were significantly correlated. Recovery accounted
for 92.1% of the cases in resistant and moderately susceptible cultivars, reaching 100% in plants inoculated with the ND isolate
(Table 2); meanwhile it was three times lower (30.1% of the plants) in susceptible and extremely susceptible diseased trees.
In the lathhouse, periodical tissue isolations for monitoring the progress of infections over a period of 127 weeks in recovered
trees, showed that the pathogen could only be isolated from trees 19 weeks after inoculation. Pathogen isolation was significantly
higher from susceptible and extremely susceptible cultivars (84.6%) than from resistant and moderately susceptible ones (33.3%).
Results showed that if a tree overcomes infection by pathogen from a single inoculation, and it is able to begin a recovery
process, it will not express wilt symptoms again in a pathogen-free environment. The pathogen remained inactive or dead over
time in recovered trees. Thus, new infections from rootlets would be necessary for new symptom expression. Recovery from Verticillium wilt is an important natural mechanism that occurs in a high percentage of infected olive trees, and can complement the resistance
of the cultivar, particularly in conditions of low inoculum densities of low virulence isolates of the pathogen in the soil. 相似文献
16.
Alejandro Solla Lorena García Andrea Pérez Ana Cordero Elena Cubera Gerardo Moreno 《Phytoparasitica》2009,37(4):303-316
The Iberian forests are suffering severe disease and mortality as a result of decline, with Quercus ilex the major species at risk. Trunk injections with potassium phosphonate, which have been used successfully to control Phytophthora cinnamomi, were tested against decline. In an area in which P. cinnamomi was isolated, Q. ilex trees showing different degrees of decline were trunk-injected. Soil properties, and measurements of soil water content (θ)
and depth to soil water table were assessed at three sites with markedly different decline incidences. Over the 5 years following
the initiation of the experiment, mean symptoms among spring-treated trees and autumn-treated trees, or among trees injected
twice a year (spring and autumn), once a year, and non-injected, were not significantly different. No effects of the treatments
on shoot growth and acorn production were observed. However, θ values under trees which recovered from decline were higher
than θ values under trees which did not recover from decline. At the site with the highest incidence of decline and tree mortality,
P. cinnamomi was rarely isolated, and the presence of gravel, soil infiltration capacities and water table depth values were significantly
higher than at the other sites, water stress being more likely to contribute to decline than P. cinnamomi. In areas in which θ is low, the distribution of phosphonate on the tree would be limited. Since the thresholds for phytotoxicity
of potassium phosphonate in Q. ilex trees at the site studied would be higher than the amounts used, rates of the chemical slightly less than those that cause
phytotoxicity should be tested. 相似文献
17.
Erich Seemüller Eckard Moll Bernd Schneider 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(2):109-119
In three trials carried out over a period of 24 years, open-pollinated seedlings of Malus sieboldii and M. sargentii and 22 apomictic rootstock selections with either M. sieboldii, M. sargentii or M. hupehensis in their parentage were examined for apple proliferation (AP) resistance in comparison to clonal M. x domestica-based rootstocks M 9, M 11, M 13, stocks of the B (Budagovski) and the Polish P series and M. robusta seedlings. Following experimental inoculation or natural infection the Golden Delicious-grafted trees on most of the M. sieboldii-derived progenies showed a high level of AP resistance expressed by low cumulative disease indices, a high percentage of
non or little affected trees, low incidence of the small fruit symptom and non or little effect on vigour. Trees on M 9 and
M 11, B 118 and M. robusta seedlings were moderately susceptible while trees on progenies with M. sargentii and M. hupehensis parentage, rootstocks of the P series, B 9, B 490 and M 13 proved highly susceptible. The screening also showed that rootstocks
with M. sieboldii and M. sargentii parentage are often highly susceptible to latent apple viruses. Trees on most of the M. sieboldii-based progenies were more vigorous than trees on standard stock M 9, whereas the vigour of some progenies from selections
with M. sargentii parentage was in the range of M 9 or even lower. Productivity was often correlated with the vigour. 相似文献
18.
Citrus psorosis virus (CPsV) was detected from citrus trees for the first time in Japan. The diagnosis was confirmed by molecular, serological,
and biological indexing. RT-PCR detected CPsV from two citrus trees among ca. 200 tested. Both trees were variety Shiranui
of [Citrus unshiu Marc. × C. sinensis (L.) Osb.] × C. reticulata Blanco, and neither had the bark scaling symptom typical of CPsV. The CPsV isolate could be genetically related to those
from Spain, Italy, Florida, and California. 相似文献
19.
E. Donaubauer 《EPPO Bulletin》1973,3(3):105-109
In 1972 several experiments were carried out in Lower Austria to study the effect a very early application of a polyhedral virus suspension may have on Neodiprion sertifer Geoffr., feeding on the needles of Finns nigra austriaca and P. silvestris. The results show that spraying in the Li-stage prevents a major loss of needles, thus confirming the outcome of the 1971 experiments. Especially for young trees or trees that were already partially defoliated the previous year, an early application is of great importance. The effect equalled the result obtained with a malathion-containing insecticide. With older trees spraying in the L2-L3 stage still gave good results. 相似文献
20.
Hiroyuki UGA Yuki O. KOBAYASHI Kyoji HAGIWARA Yohachiro HONDA Toshihiro OMURA Takahide SASAYA 《Journal of General Plant Pathology》2002,68(4):378-381
The causative virus (isolate No. 4) of gentian (Gentiana spp.) mosaic, which had been identified previously as Clover yellow vein virus (C1YVV) on the basis of host range and serological reactions, was re-identified as Bean yellow mosaic virus (BYMV) on the basis of the nucleotide sequences of the gene for the coat protein (CP) and the 3′-noncoding region, as well
as the predicted amino acid sequence of CP.
Received 16 April 2002/ Accepted in revised form 19 June 2002 相似文献