共查询到20条相似文献,搜索用时 15 毫秒
1.
Lin Huang Xu-ling Xu Xiao-qin Wu Feng-mao Chen Chao Li Jian-ren Ye 《Phytoparasitica》2010,38(4):369-377
The pine wood nematode (PWN), Bursaphelenchus xylophilus, is a disastrous pathogen of the pine forests in East Asia and Europe. Plant quarantine is one of the most important ways
to prevent its infection in current situation. A nested polymerase chain reaction (PCR) assay targeting the topoisomerse I
gene has been developed to detect PWN in this study. To assess the specificity of the assay, 44 morphologically characterized
nematode isolates including B. xylophilus, B. mucronatus, B. hofmanni, Seinura wuae, S. lii and Aphelenchoides macronucleatus were tested. Positive reactions characterized by amplification product of 509 bp were shown from all isolates of PWN. The
nested PCR assay can detect 50 femtogram (fg) of template DNA or one individual nematode, as small as an egg. The validity
was evaluated by analyzing the nematode samples extracted from the nematode-infested wood in the field. These results show
that the assay is a specific, sensitive method for detection of PWN with the potential in relation to the pest risk assessment
and quarantine regulations. 相似文献
2.
María Menéndez-Gutiérrez Margarita Alonso Enrique Jiménez Gabriel Toval Pedro Mansilla Adela Abelleira Andrea Abelleira-Sanmartín Raquel Díaz 《European journal of plant pathology / European Foundation for Plant Pathology》2018,150(4):939-953
Pinewood nematode (PWN), Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD), was detected in Spain in 2008. This gives rise to serious concern, as the disease has caused severe environmental and economic losses in Portugal and in Asian countries. We studied interspecific variation in susceptibility to pine wilt disease and differences in constitutive chemical compounds in the xylem tissue of the seven pine species -P. canariensis, P. halepensis, P. pinaster, P. pinea, P. sylvestris, P. radiata and P. taeda. Two-year-old trees were inoculated with B. xylophilus. Water potential and nematode densities were measured for each species on specific dates; whereas, wilting symptoms were recorded weekly until the end of the assay. Chemical compounds in the xylem were determined prior to inoculation. Three different resistance groups can be established in terms of the pine species susceptibility to PWN: non- to slightly-susceptible (P. canariensis, P. halepensis, P. taeda and P. pinea), susceptible (P. pinaster and P. radiata), and highly-susceptible (P. sylvestris). Nematodes migrated downward to the roots in all seven species. Constitutive xylem nitrogen, total polyphenols, and marginally phosphorus were negatively correlated with mortality caused by PWN. The most susceptible species, Pinus sylvestris, presented high levels of constitutive lipid-soluble substances and low levels of manganese, pointing to a possible relation between these components and PWN susceptibility. The results suggest P. sylvestris, P. pinaster and P. radiata forests could be severely damaged by PWN in Spain and highlight how constitutive chemical compounds such as nitrogen might play a role in resistance mechanisms against PWN. 相似文献
3.
The pinewood nematode Bursaphelenchus xylophilus is a severe pest of coniferous trees, and has been designated as a quarantine organism in the European Union. From the sequence of a satellite DNA family characterized in the genome of this nematode, we developed a PCR procedure that allowed the specific discrimination of this species from closely related Bursaphelenchus species found on coniferous trees. Moreover, because of the repetitive nature of satellite DNA, positive amplification was achieved from B. xylophilus single individuals, which should contribute to an easy diagnostic procedure for assisting in the management of this major pest of conifer forests. 相似文献
4.
5.
Irena Mavrič Pleško Mojca Viršček Marn Saša Širca Gregor Urek 《European journal of plant pathology / European Foundation for Plant Pathology》2009,123(3):261-268
In 2003, Raspberry bushy dwarf virus was found for the first time in grapevine. Since this was the first report of a non-Rubus natural host, information about it is sparse. During this study the grapevine isolates were characterised biologically, serologically
and genetically and compared with known information about Rubus isolates. Infected plant material was used for mechanical inoculation of test plants, and for serological characterisation
with monoclonal antibodies. Most of RNA 2 was sequenced and compared with other sequences from the database. Grapevine isolates
infected Chenopodium murale systemically, which is not known for raspberry isolates. They were differentiated from Slovenian raspberry isolates with
three monoclonal antibodies using TAS-ELISA. Phylogenetic analyses clustered grapevine isolates separately from raspberry
isolates. Additionally, the virus was detected using nested RT-PCR in Longidorus juvenilis nematodes collected in an infected vineyard. Grapevine isolates of RBDV are distinct from raspberry isolates. 相似文献
6.
Anil Kumar Atul Kakrana Anil Sirohi K. Subramaniam R. Srinivasan M. Z. Abdin Pradeep K. Jain 《Journal of General Plant Pathology》2017,83(2):91-97
Root-knot nematodes (RKNs) are one of the most important biotic factors limiting crop productivity in many crop plants. The major RKN control strategies include development of resistant cultivars, application of nematicides and crop rotation, but each has its own limitations. In recent years, RNA interference (RNAi) has become a powerful approach for developing nematode resistance. The two housekeeping genes, splicing factor and integrase, of Meloidogyne incognita were targeted for engineering nematode resistance using a host-delivered RNAi (HD-RNAi) approach. Splicing factor and integrase genes are essential for nematode development as they are involved in RNA metabolism. Stable homozygous transgenic Arabidopsis lines expressing dsRNA for both genes were generated. In RNAi lines of splicing factor gene, the number of galls, females and egg masses was reduced by 71.4, 74.5 and 86.6%, respectively, as compared with the empty vector controls. Similarly, in RNAi lines of the integrase gene, the number of galls, females and egg masses was reduced up to 59.5, 66.8 and 63.4%, respectively, compared with the empty vector controls. Expression analysis revealed a reduction in mRNA abundance of both targeted genes in female nematodes feeding on transgenic plants expressing dsRNA constructs. The silencing of housekeeping genes in the nematodes through HD-RNAi significantly reduced root-knot nematode infectivity and suggests that they will be useful in developing RKN resistance in crop plants. 相似文献
7.
Masamichi Isogai Koji Ishii Seisaku Umemoto Manabu Watanabe Nobuyuki Yoshikawa 《Journal of General Plant Pathology》2009,75(2):140-143
Virus-like symptoms—red ringspots on stems and leaves, circular blotches or pale spots on fruit—were found on commercial highbush
blueberry (Vaccinium
corymbosum) cultivars Blueray, Weymouth, Duke and Sierra in Japan. In PCR testing, single DNA fragments were amplified from total nucleic
acid samples of the diseased blueberry bushes using primers specific to Blueberry red ringspot virus (BRRV). Sequencing analysis of the amplified products revealed 95.7–97.7% nucleotide sequence identity with the BRRV genome.
This paper is the first report of blueberry red ringspot disease caused by BRRV in Japan.
The nucleotide sequence data reported in this paper are available in the GenBank/EMBL/DDBJ database as accessions AB469884
to AB469893 for BRRV isolates from Japan. 相似文献
8.
Khalid Pervaiz Akhtar Muhmmad Yussouf Saleem Muhammad Asghar Mushtaq Ahmad Nighat Sarwar 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(4):435-450
Sixty-nine tomato genotypes representing nine Solanum species were evaluated for resistance to Cucumber mosaic virus (CMV) subgroup IA and its aphid vector Myzus persicae. Resistance was assessed by visual scoring of symptoms in the field under natural conditions, and in the greenhouse by artificial
inoculations through aphid M. persicae and mechanical transmissions in the year 2007 and 2009. Considerable variation in responses was observed among the evaluation
methods used. Field evaluations were found liable to errors as different levels were observed for the same genotypes in the
different years, however mechanical inoculation was found to be the most useful in identifying CMV subgroup IA resistance,
in contrast aphid transmission was most useful in identifying insect transmission resistance. All genotypes observed as highly
resistant to CMV subgroup IA in the field or through vector transmission became systemically infected through mechanical inoculations.
Using mechanical inoculation, six genotypes (TMS-1 of S. lycopersicum, LA1963 and L06049 of S. chilense, LA1353, L06145 and L06223 of S. habrochaites) were found resistant and another six (L06188 and L06238 of S. neorickii, L06219 of S. habrochaites, L05763, L05776 and L06240 of S. pennellii) were found tolerant showing mild symptoms with severity index (SI) ranging 1-2 and with delayed disease development after
a latent period (LP) of 18–30 days. However, these genotypes were found to be resistant to highly resistant in the field and
through inoculation by M. persicae; and they also supported low population levels of M. persicae except TMS-1. Another nine genotypes (LA2184 of S. pimpinellifolium L., LA2727 of S. neorickii, LA0111, L06221, L06127 and L06231 of S. peruvianum L., LA1306, L06057 and L06208 of S. chmielewskii) showing a susceptible response after mechanical inoculation were highly resistant, resistant and tolerant after M. persicae transmission. The resistant genotypes, identified in the present study can be exploited in the breeding programmes aimed
at developing tomato varieties resistant to CMV subgroup IA and broadening the genetic base of CMV-resistant germplasm. The
differences observed between mechanical and aphid transmission suggests that one should consider both evaluation methods for
tomato germplasm screening against CMV subgroup IA. 相似文献
9.
Alireza Akhavan T. Kelly Turkington Berisso Kebede Kequan Xi Krishan Kumar Andy Tekauz H. Randy Kutcher James R. Tucker Stephen E. Strelkov 《European journal of plant pathology / European Foundation for Plant Pathology》2016,144(2):325-336
Infection by Pyrenophora teres f. teres (Ptt) or P. teres f. maculata (Ptm), the causal agents of the net and spot forms of net blotch of barley, respectively, can result in significant yield losses. The genetic structure of a collection of 128 Ptt and 92 Ptm isolates from the western Canadian provinces of Alberta (55 Ptt, 27 Ptm), Saskatchewan (58 Ptt, 46 Ptm) and Manitoba (15 Ptt, 19 Ptm) were analyzed by simple sequence repeat (SSR) marker analysis. Thirteen SSR loci were examined and found to be polymorphic within both Ptt and Ptm populations. In total, 110 distinct alleles were identified, with 19 of these shared between Ptt and Ptm, 75 specific to Ptt, and 16 specific to Ptm. Genotypic diversity was relatively high, with a clonal fraction of approximately 10 % within Ptt and Ptm populations. Significant genetic differentiation (PhiPT = 0.230, P = 0.001) was found among all populations; 77 % of genetic variation occurred within populations and 23 % between populations. Lower, but still significant genetic differentiation (PhiPT = 0.038, P = 0.001) was detected in Ptt, with 96 % of genetic variation occurring within populations. No significant genetic differentiation (PhiPT = 0.010, P = 0.177) was observed among Ptm populations. Isolates clustered in two distinct groups conforming to Ptt or Ptm, with no intermediate cluster. The high number of haplotypes observed, combined with an equal mating type ratio for both forms of the fungus, suggests that P. teres goes through regular cycles of sexual recombination in western Canada. 相似文献
10.
From the genome of a Japanese field isolate of the rice blast fungus, Magnaporthe oryzae, we newly identified Inago1 and Inago2 LTR retrotransposons. Both elements were found to be Ty3/gypsy-like elements whose copies were dispersed within the genome of Magnaporthe spp. isolates infecting rice and other monocot plants. Southern hybridization patterns of nine re-isolates derived from conidia
of the strain Ina168 produced after a methyl viologen treatment were not changed, indicating that the insertion pattern of
Inago elements is relatively stable. 相似文献
11.
Khalid A. Hussein Mohamed A. A. Abdel-Rahman Ahmed Y. Abdel-Mallek Saad S. El-Maraghy Jin Ho Joo 《Phytoparasitica》2012,40(2):117-126
The greater wax moth Galleria mellonella L. (Lepidoptera: Pyralidae) is occasionally found in beehives and is a major pest of stored wax. Entomopathogenic fungi have
recently received attention as possible biocontrol elements for certain insect pests. In this study, 90 isolates of Beauveria bassiana and 15 isolates of Metarhizium anisopliae were screened for proteases and lipases production. The results showed significant variations in the enzymatic action between
the isolates. In the bioassay, the selected isolates evinced high virulence against the 4th instar of the G. mellonella larvae. The isolates BbaAUMC3076, BbaAUMC3263 and ManAUMC3085 realized 100% mortality at concentrations of 5.5 × 106 conidia ml−1, 5.86 × 105 conidia ml−1, and 4.8 × 106 conidia ml−1, respectively. Strong enzymatic activities in vitro did not necessarily indicate high virulence against the tested insect pest. The cuticle of the infected larvae became dark
and black-spotted, indicating direct attack of fungus on the defense system of the insects. The LC50 values were 1.43 × 103, 1.04 × 105 and 5.06 × 104 for Bba3263AUMC, Bba3076AUMC and Man3085AUMC, respectively, and their slopes were determined by computerized probit analysis
program as 0.738 ± 0.008, 0.635 ± 0.007 and 1.120 ± 0.024, respectively. 相似文献
12.
Shigemitsu Kimura Susumu Tokumaru Kazuhiko Kuge 《Journal of General Plant Pathology》2009,75(4):322-324
Yeast-like fungi were isolated from lesions on azuki bean (cv. Shin-Kyotodainagon) seeds that had been sucked by bean bugs
in Kyoto Prefecture, Japan. On the basis of morphological and physiological characteristics and sequence data of the internal
transcribed spacer (ITS) regions including the 5.8S rDNA, these yeasts were identified as Eremothecium coryli and E. ashbyi. Pathogenicity of those yeasts was confirmed by a reinoculation test. To our knowledge, this is the first report of the occurrence
of yeast spot in azuki bean in Japan.
The nucleotide sequence data reported are available in the GeneBank/EMBL/DDBJ database as accessions AB478291–AB478309 for
E. coryli AZC1–19 and AB478310–AB478317 for E. ashbyi AZA1–8. 相似文献
13.
Ahmed A. Kheder Yasunori Akagi Hajime Akamatsu Konomi Yanaga Nitaro Maekawa Hiroshi Otani Takashi Tsuge Motoichiro Kodama 《Journal of General Plant Pathology》2012,78(1):30-38
The tomato pathotype of Alternaria alternata (A. arborescens) produces the dark brown to black pigment melanin, which accumulates in the cell walls of hyphae and conidia. Melanin has
been implicated as a pathogenicity factor in some phytopathogenic fungi. Here, two genes of the tomato pathotype for melanin
biosynthesis, ALM1 and BRM2-1, which encode a polyketide synthetase and a 1,3,8-trihydroxynaphthalene (THN) reductase, respectively, have been cloned and
disrupted in the pathogen. The gene-disrupted mutants, alm1 and brm2-1, had albino and brown phenotypes, respectively. The wild-type and the mutants caused the same necrotic lesions on the leaves
after inoculation with spores. These results suggest that melanin is unlikely to play a direct role in pathogenicity in the
tomato pathotype A. alternata. Scanning electron microscopy revealed that the conidia of both mutants have much smoother surfaces in comparison to the
wild-type. The conidia of those mutants were more sensitive to UV light than those of the wild-type, demonstrating that melanin
confers UV tolerance. 相似文献
14.
The clustered hrp genes encoding the type III secretion system in the Japanese strains MAFF301237 and MAFF311018 of Xanthomonas oryzae pv. oryzae were sequenced and compared. The strains differ in their pathogenicity, location, and year of isolation. A 30-kbp sequence comprising 29 open reading frames (ORFs) was identical in its structural arrangement in both strains but differed from X. campestris pv. campestris, X. axonopodis pv. citri, and X. axonopodis pv. glycines in certain genes located between the hpaB-hrpF interspace region. The DNA sequence and the putative amino acid sequence in each ORF was also identical in both X. oryzae pv. oryzae strains as were the PIP boxes and the relative sequences. These facts clearly showed that the structure of the hrp gene cluster in X. oryzae pv. oryzae is unique. 相似文献
15.
The genomic fragments of two open reading frames (ORFs) 1 and 2 of German and Canadian PAV isolates of Barley yellow dwarf virus (BYDV-PAV) were sequenced. Sequences only slightly differed from previously published sequences of this virus. Two polyclonal antisera against proteins encoded by ORFs 1 and 2 of a German ASL-1 isolate were developed using recombinant antigens expressed in E. coli as a fusion either to His6− or thioredoxin-tags. In Western blot analysis with total protein extracts from BYDV infected plants, antisera efficiently recognized the 99 kDa fusion protein expressed from ORF1 and ORF2 (P1–P2 protein). Later in infection the P1–P2 protein disappeared and two smaller proteins, revealing sizes of 39 and 60 kDa, could be detected. 相似文献
16.
Akira Kawaguchi 《Journal of General Plant Pathology》2011,77(5):299-303
Forty-one strains of Rhizobium vitis, either tumorigenic (Ti) or nonpathogenic, were characterized using multilocus sequence analysis (MLSA) of the partial nucleotide
sequences of pyrG, recA, and rpoD. The strains separated into seven clades. Rhizobium vitis (Ti) strains isolated from Japan were divided into five genetic groups (A to E), and nonpathogenic R. vitis strains were divided into two genetic groups (F and G). This result suggests that there are new genetic groups of R. vitis in Japan. Among these groups, members of A and B groups are widely distributed throughout Japan. 相似文献
17.
Rudra P. Singh Andrea D. Dilworth Xiaoping Ao Mathuresh Singh Virendra K. Baranwal 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(4):691-694
Surveys of Impatiens and Verbena species in local nurseries in Fredericton, Canada and Verbena species in New Delhi, India showed widespread infection of Citrus exocortis viroid (CEVd) in vegetatively-propagated and seed-grown plants. To determine viroid seed transmission, samples of eight varieties
of Impatiens and 11 varieties of Verbena were obtained from four commercial sources. All 19 samples collected contained viroid infection irrespective of variety.
The presence of viroid in non-germinated seed was 21%, while the transmission rate in seedlings was 66% in Impatiens walleriana in 2006. Following 2 years of seed storage, the respective figures were 6% and 26%. Similarly, in Verbena x hybrida the presence of viroid in seed was 13% in 2006 with a seed-transmission rate in seedlings of 28%, while the respective figures
after 2 years of storage were 5% and 45%. 相似文献
18.
Davide Giovanardi Davide Dallai Emilio Stefani 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(4):761-771
Bacterial leaf/fruit spot and canker of stone fruits, caused by Xanthomonas arboricola pv. pruni, is a recurrent disease in Italy. A set of 23 strains has been isolated in peach and plum orchards in an intensively stone fruit cultivated area located in north-eastern Italy. They were all identified as X. arboricola pv. pruni by means of phytopathological and serological features: hypersensitive reaction on bean pods, pathogenicity test on immature peach or plum fruitlets, identification by immunofluorescence assay and conventional PCR. Phylogenetic analysis based on sequencing of the gyrB housekeeping gene of the isolates showed that they formed a unique clade, well characterised and separated from other xanthomonads. An insight into the genetic population features was attempted by rep-PCR analysis, using the ERIC, REP and BOX primers. The combined rep-PCR fingerprints showed a slight intra-pathovar variation within our isolates, which grouped in five close clusters. Copper resistance has been assessed in vitro for our whole X. arboricola pv. pruni collection, highlighting that two isolates show a level of resistance in vitro up to 200 ppm of copper. Nonetheless, the copLAB gene cluster, present in many other species of Xanthomonads, was not detected in any isolate, confirming the presence of a still unknown mechanism of copper detoxification in our Xanthomonads arboricola pv. pruni tolerant/resistant strains. 相似文献
19.
The invasive small cypress bark beetle, Phloeosinus aubei (Coleoptera, Curculionidae, Scolytinae) has two flights in Central-Europe, however, it was unclear, whether this corresponds to two reproductive periods, when nuptial chambers are formed and galleries initiated. The aim of this study was to clarify the life-cycle of P. aubei in Hungary, representing populations in the range of invasion, and to compare preferences towards some popular cultivars of Thuja and Juniper ornamental trees. In order to reveal which is the pioneering gender, and to confirm females’ preferences between healthy and broken trunks behavioral tests were conducted. Results showed that adults prepare hibernation tunnels from August until October. Sex ratio of overwintering adults was nearly equal. The significantly highest number of hibernation tunnels was found on Thuja plicata Atrovirens (mean±S.E.: 6.0±0.7/tree), followed by T. occidentalis Smaragd (2.2±0.8), Juniperus chinensis Spartan (1.6±0.6), and J. scopulorum Blue Arrow (0.2±0.2). Nuptial chambers were made from April until June, by singly females, never by males. Females chose broken, drying trunks over healthy ones. Adults of the next generation emerged from the galleries from August until October. By October adults emerged from 94% of the galleries, and larvae were found only in 6% of the galleries. These results showed that the autumn flight of P. aubei is linked to making hibernation tunnels, while the spring flight to producing nuptial chambers. The latter corresponds to a single reproductive period per year. Control measures against adults should be timed to these two specific periods of the season. 相似文献
20.