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Abhinandan?Deora Yasuyuki?HashidokoEmail author Md.?Tofazzal?Islam Satoshi?Tahara 《European journal of plant pathology / European Foundation for Plant Pathology》2005,112(4):311-322
A total of 150 bacteria were isolated from rhizoplanes of the host and non-host plants of a phytopathogenic Peronosporomycete Aphanomyces cochlioides. Upon screening, 5% of the isolates were evaluated as antagonists as they inhibited radial growth of A. cochlioides AC-5 hyphae in a dual culture assay. In addition, those antagonistic bacteria also induced characteristic morphological alterations in the A. cochlioides AC-5 hyphae that grew towards bacterial colonies. Hyphal morphological alterations observed in AC-5 and other tested strains of Peronosporomycetes included excessive branching, curly growth, unusually longer and pointed tip formation and swelling; all of these were comparable to the alterations induced by known antimicrobial compounds. Among the antagonistic bacteria, Pseudomonas sp. strain EC-S101 induced a unique branching pattern (tree-like) in AC-5 hyphae by continuous apical bifurcation of successive hyphae, where increases in number of branches and hyphal area were linearly correlated with time up to 10 h. Our observations suggested that the pathogen might have lost its ability of normal branch production; however maintained the capability of self-branching. Soluble extracts from the culture fluids of Pseudomonas sp. strain EC-S101 and Stenotrophomonas maltophilia EC-S105 induced similar excessive branching and curly growth in A. cochlioides hyphae as the respective bacterium. These results revealed that bacterial metabolites appeared to be responsible for induction of morphological alterations. Interestingly, the antagonistic bacteria that induced hyphal morphological alterations, also efficiently suppressed in vivo damping-off disease caused by AC-5. We suggest that antagonistic rhizoplane bacteria have the capability to induce diverse morphological alterations in Peronosporomycetes hyphae during in vitro interactions. Hyphal morphological alterations associated with growth inhibition and the induction of characteristic morphological changes indicate antagonistic activity against the Peronosporomycete. 相似文献
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Effect of soil type,organic matter content,bulk density and saturation on clubroot severity and biofungicide efficacy 
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下载免费PDF全文 Growth room experiments were conducted to assess the interaction of soil type, biofungicides, soil compaction and pathotype/host on infection and symptom development caused by Plasmodiophora brassicae, the cause of clubroot on Brassica spp. In two initial experiments, four soil types (peat soil, mineral soil, non‐calcareous sand, soil‐less mix), two biofungicides (Bacillus subtilis, Clonostachys rosea), and two pathotypes (3 and 6, Williams’ differential set) were assessed. Differences in clubroot severity associated with soil type were unexpectedly small and variable. Prestop (C. rosea) was often more effective than Serenade (B. subtilis) at reducing clubroot levels on peat and mineral soils, but less effective than Serenade on sand. Inoculation with pathotype 3 often resulted in a slightly higher mean severity than pathotype 6. The interaction of soil type × biofungicide was similar on both canola (B. napus) and Shanghai pak choy (B. rapa subsp. chinensis), whether the soil was kept saturated or allowed to drain after inoculation. The impact of soil type on biofungicide efficacy might explain, in part, why biofungicides are more effective in one location than another. The observation that clubroot severity in soil‐less mix was affected by compaction led to an investigation of soil bulk density. Severity was higher in soil‐less mix that was more compacted than in the initial experiments, and was lower in peat and mineral soils when soil bulk density was reduced by adding soil‐less mix. In this study, soil bulk density had a larger impact on clubroot than soil type, organic matter or pathotype. 相似文献
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Travis J. Cranmer Fadi Al-Daoud Bruce D. Gossen Abhinandan Deora Sheau-Fang Hwang Mary Ruth McDonald 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(2):435-446
Pratylenchus zeae parasitizes various crops and damages the host roots, resulting in decreased yield and quality of the host plants. Alignments of mitochondrial DNA (mtDNA) Cytochrome Oxidase I (COΙ) sequences revealed the genetic variation among Pratylenchus species. The results indicated 0.2–2.4% intraspecific variations for mtDNA COI sequences among eight P. zeae populations, and 25.4–35.1% interspecific variations between P. zeae and other Pratylenchus species. Based on the mtDNA COΙ region, a loop-mediated isothermal amplification (LAMP) assay was developed for the rapid and specific detection of P. zeae. The optimal conditions for the LAMP assay were 64 °C for 40 min. The LAMP products were confirmed using conventional polymerase chain reaction (PCR), analysis with the restriction enzyme Bam HI and visual inspection by adding SYBR Green I to the products. The LAMP assay could detect P. zeae populations from different hosts and different geographical origins specifically. The LAMP assay was also sensitive, detecting 0.1 individual P. zeae, which was 10 times more sensitive than conventional PCR. This is the first report of the detection of Pratylenchus spp. using LAMP. In addition, the results also suggested that use of the COI gene might allow for good resolution at the Pratylenchus species level. 相似文献
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Abhinandan Deora Yasuyuki Hashidoko Md. Tofazzal Islam Yuriko Aoyama Toshiaki Ito Satoshi Tahara 《Journal of General Plant Pathology》2006,72(1):57-64
We observed that an antagonistic rhizoplane bacterium Pseudomonas sp. strain EC-S101 induces excessive lateral and apical branching in the hyphae of a root rot phytopathogen Aphanomyces cochlioides AC-5 resulting in radial growth inhibition of hyphae in a dual culture assay. Confocal laser scanning microscopic observations
using fluorescent stains indicated an increased quantity of nuclei and lipid bodies in the affected hyphae during the early
stage (less affected hyphae) at day 3 of interaction. At a more advanced stage (severely affected hyphae) at day 3, nuclei
became smaller and round-shaped compared with the oval shape in AC-5 control hyphae. After 7 days, nuclei disintegrated, and
the nuclear materials were released into the disorganized cytoplasm. With transmission electron microscopy at 5 days of interaction,
we found that the cell walls of AC-5 hyphae were considerably thicker than those of the control. Enlarged vacuoles, lipid
bodies sunk into vacuoles, and vacuoles filled with electron-dense material, followed by an invagination of the AC-5 hyphal
cell wall, were commonly observed. Nonmembranous electron-transparent inclusion bodies irregular in size were often distributed
in the affected hyphae. By integrating our observations, we conclude that antagonistic effects evoked by strain EC-S101 resulted
in the death of AC-5 hyphae, which might contribute to the suppression of A. cochlioides AC-5-linked damping-off disease in its host plants.
The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under the accession number AB190286 相似文献
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Bordetella bronchiseptica is a zoonotic respiratory pathogen commonly found in domesticated farm and companion animals, including dogs and cats. Here, we report isolation of B. bronchiseptica from a sputum sample of a cystic fibrosis patient recently exposed to a kitten with an acute respiratory illness. Genetic characterization of the isolate and comparison with other isolates of human or feline origin strongly suggest that the kitten was the source of infection. 相似文献
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Md. Tofazzal Islam Mitsuyoshi Sakasai Yasuyuki Hashidoko Abhinandan Deora Yasuko Sakihama Satoshi Tahara 《Journal of General Plant Pathology》2007,73(5):324-329
A modified medium was used to culture mycelium and produce a large quantity of zoospores of Aphanomyces cochlioides, a principal pathogen of damping-off disease of sugar beet and root rot disease of spinach. The semisolid medium consisted
of 17 g corn meal agar (CMA) added with 4 g of yeast extract (YE) per liter of 50 mM phosphate buffer (pH 6.8–7.0). This medium
supported the production of ca. 106 zoospores ml−1 in 6-day-old cultures, approximately 11-fold higher than the commonly used CMA (17 g CMA per liter of water, pH 6.0 ± 0.2).
Although morphological characters of the zoospores produced from the hyphae grown on CMA and CMA + YE were almost similar,
they contrasted their developmental strategy after encystment induced by mechanical agitation. Cystospores originating from
the zoospores on CMA regenerated zoospores (>80%), while those from CMA + YE germinated (ca. 80%) and produced hyphae. Furthermore,
4–10% of the germinated cystospores on CMA + YE had double germ tubes. The soluble protein profiles of zoospores produced
on CMA and on CMA + YE demonstrated that several proteins were either different or expressed differently. Our results suggest
that the culture medium directly influences zoosporogenesis in A. cochlioides hyphae and the developmental strategy of the produced zoospores. 相似文献
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Peanut (Arachis hypogaea L.) is known to be sensitive to genotype-by-environment interaction (GEI) effects. While previous studies have reported strong GEI effects on peanut yield, most of those studies involved a relatively small number of unrelated genotypes. We examined the extent of GEI effects in elite Virginia-type peanut using a large population of recombinant inbreed lines (RILs). Two-hundred-sixty-six F7 RILs derived from different cultivars were grown in three environments. Net pod yield (NPY) was evaluated along with 11 other traits. ANOVA revealed that genotype and environment affected all of the examined traits, except for the triplet trait. The substantial influence of the environment was also demonstrated in a genetic-parameter analysis, in which the phenotypic variation coefficients were almost double those for genotypic variation. Still, relatively high heritability and genetic gain values were found for pod weight and NPY. Since NPY is the main target for selection, it was analyzed further. Path analysis showed that NPY is most directly influenced by pod weight and the shelling ratio. A significant GEI effect on NPY was identified using an AMMI model that described 42.7% of the total variation. This GEI component was subjected to a principal components analysis, which confirmed that the variability due to the different environments was greater than the variability that could be attributed to the different genotypes. Yet, several lines had stable yields across environments. These results demonstrate the importance of multi-location phenotyping for QTL analyses and crop improvement in peanut. 相似文献
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