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Cytological characteristics of microconidia of <Emphasis Type="Italic">Magnaporthe oryzae</Emphasis>
Izumi Chuma Takeshi Shinogi Naoki Hosogi Ken-ichi Ikeda Hitoshi Nakayashiki Pyoyun Park Yukio Tosa 《Journal of General Plant Pathology》2009,75(5):353-358
The inner cellular structure of microconidia of Magnaporthe oryzae was examined using fluorescent probes and electron microscopic techniques. The volume of the nucleus relative to the cell
was significantly larger in microconidia than in macroconidia or vegetative hyphae, similar to observations for spermatia
of other fungi. Selective fluorescent staining revealed that cytosolic RNA was less abundant in microconidia than in macroconidia
and germ tubes, suggesting that general metabolic activity in microconidia is low. Consistently, GFP expression driven by
the TrpC promoter was highly active during the formation of phialides and microconidia but gradually decreased as the microconidia
matured. Such data suggest that microconidia are in a quiescent or dormant state. 相似文献
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Murakami J Tosa Y Kataoka T Tomita R Kawasaki J Chuma I Sesumi Y Kusaba M Nakayashiki H Mayama S 《Phytopathology》2000,90(10):1060-1067
ABSTRACT A genetic cross was performed between a Setaria isolate (pathogenic on foxtail millet) and a Triticum isolate (pathogenic on wheat) of Magnaporthe grisea to elucidate genetic mechanisms of its specific parasitism toward wheat. A total of 80 F(1) progenies were obtained from 10 mature asci containing 8 ascospores. Lesions on wheat leaves produced by the F(1) progenies were classified into four types, which segregated in a 1:1:1:1 ratio. This result suggested that the pathogenicity of the F(1) population on wheat was controlled by two genes located at different loci. This idea was supported by backcross analyses. We designated these loci as Pwt1 and Pwt2. Cytological analyses revealed that Pwt1 and Pwt2 were mainly associated with the hypersensitive reaction and papilla formation, respectively. 相似文献
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Akinori Kiba Kyon Ye Lee Kouhei Ohnishi Pyoyun Park Hitoshi Nakayashiki Yukio Tosa Shigeyuki Mayama Yasufumi Hikichi 《Physiological and Molecular Plant Pathology》2009,74(1):45-54
Pseudomonas cichorii is the major causal agent of bacterial rot disease in lettuce, and apoptosis-like programmed cell death is closely associated with disease development. Depletion of cellular ATP and expression of the alternative oxidase gene was observed in lettuce leaves inoculated with P. cichorii suggesting mitochondrial dysfunction. Cytochemical observation showed production of reactive oxygen species in mitochondria of P. cichorii-inoculated lettuce leaf cells. Release of cytochrome c into the cytosol was also induced by inoculation with the bacterium. Superoxide production was observed in the mitochondrial fraction isolated from P. cichorii-infected leaves much more intense than water-treated leaves. Loss of swelling ability was also observed in the mitochondrial fractions following inoculation with P. cichorii. Intriguingly, inhibitors of the mitochondrial respiratory complex III prevented loss of swelling ability, whereas superoxide generation was scarcely affected by inhibitors of mitochondrial permeability transition in the mitochondrial fractions. Inhibitors of the mitochondrial respiratory complex III and mitochondrial permeability transition delayed not only P. cichorii-induced cell death, but also disease development. In contrast, P. cichorii-induced DNA fragmentation was not inhibited in the presence of either type of inhibitor. The findings suggest that mitochondria may play a crucial role in DNA fragmentation-independent cell death pathway(s). 相似文献
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Masaru Sakamoto Yasuomi Tada Hitoshi Nakayashiki Yukio Tosa Shigeyuki Mayama 《Journal of General Plant Pathology》2005,71(6):387-394
Reactive oxygen species (ROS) are thought to be involved in various forms of programmed cell death (PCD) in animal and plant
cells. PCD, along with the production of ROS, occurs during plant–pathogen interactions. Here we show that victorin, a host-specific
toxin produced by Cochliobolus victoriae, which causes victoria blight of oats, induces two phases of intracellular ROS production in victorin-sensitive oat mesophyll
cells. The initial production of ROS is restricted at mitochondria and not accompanied with cellular oxidative damage. Later
production of ROS is dispersed into cells concomitant with lipid peroxidation, chloroplast dysfunction, and cell death. Superoxide
dismutase can clearly suppress the initial ROS production and delay the progression of cell death. These data indicate that
the initial ROS production may be involved in the cell death induction process, and the later ROS production may play important
roles in events leading to cellular disruption. 相似文献
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Kenji Hirata Yukio Tosa Hitoshi Nakayashiki Shigeyuki Mayama 《Journal of General Plant Pathology》2005,71(5):340-344
We examined whether PWT4, an avirulence gene of Avena isolates of Magnaporthe oryzae toward wheat, corresponded to Rwt4, a resistance gene identified in wheat cultivar Norin 4, in a one-to-one manner. Twelve wheat cultivars were inoculated with 65X1, an F1 culture with PWT4 derived from a cross between an Avena isolate (Br58) and a Triticum isolate (Br48). Three wheat cultivars (Norin 26, Shin-chunaga, Cheyenne) were resistant and therefore selected as possible carriers of Rwt4. The three cultivars were then inoculated with a population derived from a backcross of 61M2 carrying PWT4 with Br48 carrying pwt4. Segregation analyses revealed that PWT4 operates against the three cultivars. If PWT4 corresponds to Rwt4 in a one-to-one manner, all three cultivars should carry Rwt4. To test if this is the case, the three cultivars were crossed with Chinese Spring (a noncarrier of Rwt4) and Norin 4. When F2 seedlings from Chinese Spring × Norin 26, Chinese Spring × Shin-chunaga, and Chinese Spring × Cheyenne were inoculated with 61M2, resistant and susceptible seedlings segregated in a 3 : 1 ratio. On the other hand, crosses between the three cultivars and Norin 4 yielded no susceptible F2 seedlings. These results indicate that all three cultivars carry Rwt4. Considering all results, we concluded that PWT4 corresponds to Rwt4 in a one-to-one manner. An inoculation test with Chinese Spring–Cheyenne chromosome substitution lines indicated that Rwt4 is located on chromosome 1D. 相似文献
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Vu Thi Bich Hau Kenji Hirata Jiro Murakami Hitoshi Nakayashiki Shigeyuki Mayama Yukio Tosa 《Journal of General Plant Pathology》2007,73(1):22-28
Rwt4 (synonym of Rmg1), a temperature-insensitive gene for resistance to Avena isolates of Magnaporthe oryzae, was identified in wheat cultivar Norin 4 in a seedling assay. The significance of Rwt4 was evaluated using flag leaves of wheat cultivars. At high temperature, Norin 4 was completely resistant to Avena isolate Br58, while Chinese Spring, a noncarrier of Rwt4, was susceptible. Genetic analysis of F2 plants derived from Norin 4 × Chinese Spring indicated that the resistance of flag leaves of Norin 4 to the Avena isolate is conditioned by a single major gene. Segregation analysis of F3 seedlings derived from the F2 plants showed that the major gene is actually Rwt4. These results suggest that Rwt4 is effective against Avena isolates throughout the growth stages. Furthermore, screening of Pyricularia isolates from various hosts suggested that Panicum isolates are possible carriers of the corresponding avirulence gene, PWT4. Segregation analyses of F2 and F3 seedlings showed that Panicum isolates actually carry PWT4, and, therefore, that Rwt4 is also effective against Panicum isolates. On the other hand, none of the Oryza, Setaria, Triticum, and Lolium isolates tested was a carrier of PWT4. The significance of this finding is discussed from the viewpoint of epidemics of blast disease on wheat. 相似文献
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Yutaka Iwamoto Kai Inoue Shinji Nishiguchi Katsunari Matsuura Masataka Aino Hitoshi Nakayashiki Kenichi Ikeda 《Journal of General Plant Pathology》2017,83(4):240-243
Lettuce big-vein disease, caused by Mirafiori lettuce big-vein virus and Lettuce big-vein associated virus, is suppressed when the pH of field soil becomes acidic. Therefore, we evaluated the effect of soil pH on the activities of Olpidium virulentus, the vector of the viruses. We found that acidic soil, pH less than 6.0, significantly reduced O. virulentus infection of the root and influenced the detection rate of zoospores released in the surrounding water. We concluded that acidic soil suppresses zoospore release from zoosporangia. 相似文献
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