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271.
Hsiu-Lin Liu Ching-Chung Chen Chan-Pin Lin 《European journal of plant pathology / European Foundation for Plant Pathology》2007,117(3):281-291
Pear decline (PD) is an important phytoplasmal disease that occurs mainly in Europe and North America. In 1994, pear trees
exhibiting symptoms typical of PD disease were observed in orchards of central Taiwan. The sequence of 16S rDNA and 16S–23S
rDNA intergenic spacer region (ISR) of the causative agent of pear decline in Taiwan (PDTW) were amplified with polymerase
chain reaction (PCR) using a DNA template prepared from the diseased leaves. Sequence analysis of 16S rDNA revealed that the
PDTW agent was closely related to the phytoplasmas of the apple proliferation group that cause diseases in stone fruits, pear
and apple. Consistent with the result of 16S rDNA sequence analysis, sequence analysis of the 16S–23S rDNA ISR and putative
restriction site analyses of 16S rDNA and 16S–23S rDNA ISR sequences provided further support for the view that the PDTW phytoplasma
causing pear decline in Taiwan may represent a new subgroup of the apple proliferation group. According to the rDNA sequence
of PDTW phytoplasma, two specific PCR primer pairs, APf2/L1n and fPD1/rPDS1, were designed in this study for the detection
of the etiological agent in pear trees and insect vectors. Based on the sequence analyses of the PCR-amplified fragments,
two species of pear psyllas, Cacopsylla qianli and Cacopsylla chinensis, were found to carry PDTW phytoplasma. 相似文献
272.
Mara Quaglia Antonio Zazzerini 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(4):393-400
Diaporthe helianthi the causal agent of sunflower (Helianthus annuus) stem canker, causes significant reductions in yield and oil content in most sunflower-growing areas. With the aim of enhancing
host resistance, we selected in vitro sunflower calli against culture filtrates of two pathogen isolates (7/96 and 101/96).
This technique may be an effective and rapid tool to discriminate the most virulent D. helianthi isolate and to screen for host resistance in the early stage of a breeding programme. Further investigation on the mechanisms
involved in defence pathways showed no induction of salicylic acid and pathogenesis-related proteins in calli, indicating
that the host resistance is not associated with Systemic Acquired Resistance but probably other biochemical mechanisms. 相似文献
273.
Takao Tsukiboshi Yoshiaki Chikuo Yoko Ito Yosuke Matsushita Koji Kageyama 《Journal of General Plant Pathology》2007,73(4):293-296
Root and stem rot with wilt of above ground parts of cultivated chrysanthemums was first found in Ibaraki, Toyama and Kagawa
prefectures, Japan in 2002 and 2003. Pythium species were isolated from the diseased tissues and identified as P. dissotocum, P. oedochilum, P. sylvaticum, P. ultimum var. ultimum and asexual strains of P. helicoides based on their morphologies and sequences of rDNA-ITS region. All the Pythium species were strongly pathogenic to chrysanthemums in pot conditions and were reisolated from the inoculated plants. Because
Pythium root and stem rot of chrysanthemum has never been reported in Japan, we propose that this is a new disease that can
be caused by the five Pythium species. 相似文献
274.
Valérie Gravel Hani Antoun Russell J. Tweddell 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(4):457-462
The effect of indole-acetic acid (IAA) on the development of symptoms caused by Pythium ultimum on tomato plants was investigated using different bioassays. Application of IAA (5 μg ml−1) on tomato seedlings inoculated with P. ultimum did not affect their emergence suggesting that IAA did not affect the severity of Pythium damping-off. However, IAA was shown
to influence the development of P. ultimum symptoms on tomato plantlets. Low concentrations of IAA (0–0.1 μg ml−1) within the rhizosphere of plantlets increased the severity of the symptoms caused by P. ultimum, while higher concentrations (10 μg ml−1), applied either by drenching to the growing medium or by spraying on the shoot, reduced the symptoms caused by this pathogen.
In addition, the study demonstrated that P. ultimum produces IAA in liquid culture amended with L-tryptophan, tryptamine or tryptophol (200 μg ml−1) and in unamended culture. 相似文献
275.
Mwafaida J. Mghalu Masashi Horibe Mayumi Kubota Hirokazu Kawagishi Mitsuro Hyakumachi 《Journal of General Plant Pathology》2007,73(4):235-241
Isolates from 18 anastomosis groups (AGs) of binucleate Rhizoctonia were screened for lectin activity. Eight AGs (AG-B, AG-D, AG-F, AG-G, AG-H, AG-I, AG-R and AG-U) had low to moderate lectin
activities. Among these, members of AG-D and AG-I had the highest activity. Partially purified lectins from AG-D preferentially
agglutinated human blood type A to type B and O. Mucin and galactose were the most potent inhibitors among the tested carbohydrates.
The molecular masses of these lectins ranged from 12.7 kDa for the monomer to 62 kDa for the pentamer type. Proline, alanine,
glutamic acid, aspartic acid, leucine, threonine, serine and tyrosine were the major amino acid components of these lectins.
Lectins from AG-D were stable at 4–50°C and from pH 6.0 to 10.0. When assayed with isoelectric focusing, these lectins gave
bands at pI 9.30. Specificity of lectins from AG-D to galactose and its derivatives suggest a possible recognition role in
this fungal species. 相似文献
276.
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
277.
278.
David Ezra Tammy Kroitor Avraham Sadowsky 《European journal of plant pathology / European Foundation for Plant Pathology》2007,118(2):183-191
Mal secco disease of citrus caused by Phoma tracheiphila is a devastating disease in the Mediterranean basin. Susceptible citrus species include lemon, citron, lime and others. Trees
attacked by the fungus show characteristic symptoms; the smallest twigs die first, followed by the larger branches. Eventually,
the whole tree is killed. The symptoms are clear in the orchards but by the time they are visible the disease is already well
established. The need for a sensitive, reliable and rapid diagnostic method for the early identification of the fungus in
trees and fruit exists. We have developed a PCR-based method for the identification of P. tracheiphila from plant tissues including fruit. Any such method must take into account the genetic variability in the pathogen population.
Molecular methods were used to compare different isolates of P. tracheiphila. This study found no significant differences between different isolates from different citrus species from different parts
of Israel. 相似文献
279.
Toshiyuki Usami Shu Ishigaki Hiroko Takashina Yuko Matsubara Yoshimiki Amemiya 《Journal of General Plant Pathology》2007,73(2):89-95
Japanese isolates of Verticillium dahliae, a causal agent of wilt disease in many plants, are classifiable into pathotypes based on their pathogenicity. Because these
pathotypes are morphologically indistinguishable, establishing a rapid identification method is very important for the control
of this pathogen in Japan. For cloning DNA fragments that are useful for identification and specific detection of V. dahliae pathotypes, we performed random amplified polymorphic DNA (RAPD) analyses using various isolates. One polymerase chain reaction
(PCR) product, E10-U48, was specific to isolates pathogenic to sweet pepper. The other product, B68-TV, was specific to race
1 of isolates pathogenic to tomato. The specificity of these sequences was confirmed by genomic Southern hybridization. Further
analyses revealed that the region peripheral to B68-TV obtained from the genomic DNA library includes the sequence specific
to all isolates pathogenic to tomato (races 1 and 2). Moreover, sequence tagged site (STS) primers designed from B68-TV and
its peripheral region showed race-specific and pathotype-specific amplification in a PCR assay. The probes and primers obtained
in this study are likely to be useful tools for the identification and specific detection of pathotypes and races of V. dahliae.
The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under accession number AB095266. 相似文献
280.
PCB removal,soil enzyme activities,and microbial community structures during the phytoremediation by alfalfa in field soils 总被引:1,自引:1,他引:1
Chen Tu Ying Teng Yongming Luo Xianghui Sun Shaopo Deng Zhengao Li Wuxing Liu Zhihong Xu 《Journal of Soils and Sediments》2011,11(4):649-656