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1.
A Cucumber mosaic virus was newly isolated from Silene armeria and was characterized by biological, serological and molecular biological methods. Received 4 July 2001/ Accepted in revised form 28 August 2001  相似文献   
2.
Cellular fatty acids were analyzed to characterize and differentiate 34 isolates of Rhizoctonia species representing binucleate Rhizoctonia AG-D (I), AG-D (II), R. solani AG 2-2 IIIB, AG 2-2 LP, R. circinata var. circinata and var. oryzae associated with turfgrass diseases in Japan. Myristic, pentadecanoic, palmitic, palmitoleic, stearic, oleic, linoleic and linolenic acids were consistently present in varying quantities in all isolates. Heptadecanoic and 9-heptadecenoic acids were present in isolates of Rhizoctonia AG-D (I), AG-D (II), R. solani AG 2-2 IIIB and AG 2-2 LP but not in isolates of R. circinata var. circinata and var. oryzae. Palmitic, oleic and linoleic acids were the major fatty acids found, constituting 88.30-98.37% of the whole-cell fatty acid content. The remaining fatty acids were present in smaller amounts. Isolates within a single group were closely clustered, whereas isolates from different groups were clearly distinguishable based on average linkage cluster analysis of cellular fatty acids. Principal component analysis, based on all fatty acids detected, confirmed the distinct separation of isolates representing the six groups of Rhizoctonia species obtained from turfgrasses. These results suggested that fatty acid analysis is useful for the characterization and differentiation of isolates of Rhizoctonia species associated with turfgrass diseases. Received 21 May 2001/ Accepted in revised form 28 September 2001  相似文献   
3.
Five fungal isolates (Trichoderma, Fusarium, Penicillium, Phoma and a sterile fungus) from zoysiagrass rhizosphere that promote plant growth were tested for their ability to induce systemic resistance in cucumber plants against Colletotrichum orbiculare. Roots of cucumber plants were treated with these fungal isolates using barley grain inocula (BGI), mycelial inocula (MI) or culture filtrate (CF). Most isolate/inoculum form combinations significantly reduced the disease except BGI of Trichoderma. These fungal isolates were also evaluated for induction of systemic resistance against bacterial angular leaf spot and Fusarium wilt by treatment with BGI. Penicillium, Phoma and the sterile fungus significantly reduced the disease incidence of bacterial angular leaf spot. Phoma and sterile fungus protected plants significantly against Fusarium wilt. Roots treated with CFs of these fungal isolates induced lignification at Colletotrichum penetration points indicating the presence of an elicitor in the CFs. The elicitor activity of CFs was evaluated by the chemiluminescence assay using tobacco callus and cucumber fruit disks. The CFs of all isolates elicited conspicuous superoxide generation. The chemiluminescence activity of the CF of Penicillium was extremely high, and its intensity was almost 100-fold higher than that of other isolates. The chemiluminescence activity was not lost following treatment with protease or autoclaving or after removal of lipid. The MW 12,000 dialyzed CF fraction was highly effective in eliciting chemiluminescence activity. Chemiluminescence emission from cucumber fruit disks treated with Penicillium was the same as that obtained from tobacco callus, except that the lipid fraction also showed a high activity. Both the MW 12,000 fraction and the lipid fraction induced lignification in the epidermal tissues of cucumber hypocotyls.  相似文献   
4.
Three isolates of binucleateRhizoctonia (BNR) were tested for biological control of damping-off of cucumber seedlings caused byRhizoctonia solani AG 2-2 and AG 4. BNR isolates L2 (AG Ba) and W1 and W7 (AG A) provided protection of 58 to 71% against virulent isolate C4 of AG 4 and 64 to 75% protection against virulent isolate RH 65 of AG 2-2. Varying protection was provided to the seedlings by the BNR isolates against the virulentR. solani from the two AGs depending on their combination. The BNR isolates did not vary in providing protection to the seedling when tested against virulent C4 when both isolates were inoculated using three different methods,viz. in water agar, combination of water agar and soil and using soil alone. Protection of 58 to 71 % was provided by the isolates when inoculation was done on the hypocotyl using water agar, 62.8 to 75% using the combination of water agar and soil, and 75 to 85% when inoculation of both isolates was done in soil. Pre-incubation of BNR W7 or delayed inoculation of C4 (from 0.5 day to longer duration) using the different methods provided an increased protection to the seedlings to give complete inhibition of damping-off disease. Simultaneous inoculation of both BNR W7 and C4 using the three methods failed to provide protection to the seedlings. Among the BNR isolates, BNR W7 showed plant growth promotion in terms of significant increase in plant height (P=0.01) and fresh weight (P=0.05).  相似文献   
5.
An undescribed spherical virus ca. 30 nm in diameter was isolated from gladiolus (Gladiolus spp.) plants in Japan. The virus had a moderate host range within eight families. Purified virus preparations contained two large RNA components and one coat protein with mobility similar to Cycas necrotic stunt virus (CNSV) from cycas (Cycas revolute). The virus was serologically closely related to CNSV. Its nucleotide sequence of the coat protein gene had 89% common identity with that of CNSV. These results indicated that the virus isolated from gladiolus is a new strain of CNSV. The nucleotide sequence data reported are available in the DDBJ/EMBL/Gen Bank databases under the accession number AB237656.  相似文献   
6.
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   
7.
ABSTRACT Root and stem rot of cut-flower roses (Rosa spp.) was observed in commercial glasshouse-grown roses in 10 prefectures of Japan from 1998 through 2001. Binucleate-like Rhizoctonia spp. were isolated mainly from the disease plants. In all, 670 isolates were divided into two types based on cultural appearance; 168 isolates of light brown to brown type and 502 isolates of whitish type. A hyphal anastomosis reaction using representative isolates from each type revealed that the light brown to brown type belonged to anastomosis group G (AG-G), whereas the whitish type (AG-CUT) failed to anastomose with tester strains of binucleate Rhizoctonia AG-A through AG-S. Neither isolates of AG-G nor AG-CUT anastomosed with tester strains of a previously reported unknown AG (AG-MIN) of binucleate Rhizoctonia spp. collected from miniature roses. In pathogenicity tests, randomly selected isolates of the three groups caused root and stem rot on cut-flower and miniature roses. To differentiate AG-CUT and AG-MIN from known AGs of binucleate Rhizoctonia spp., restriction fragment length polymorphism (RFLP) and sequence analyses of a ribosomal (r)DNA internal transcribed spacer (ITS) region were conducted. Among the eight restriction enzymes used, HaeIII produced DNA banding patterns for AG-CUT that differed from those of tester strains and AG-MIN. Additionally, restriction profiles of AG-MIN differed from those of all tester strains. AG-G isolates from cut-flower roses had the same RFLP pattern as the tester strains of AG-G. Based on the results of hyphal anastomosis and RFLP and sequence analysis of an rDNA-ITS region, we propose that AG-CUT be designated AG-T and AG-MIN be designated AG-U, two new AGs of binucleate Rhizoctonia spp. The phylogenetic tree based on the sequence data of the rDNA-ITS region showed that isolates of AG-MIN were in a distinct clade from other AGs, whereas isolates of AG-CUT were in the same clade as those of AG-A. More detailed phylogenetic analysis besides rDNA-ITS region might be necessary for AG classification of binucleate Rhizoctonia spp.  相似文献   
8.
The rDNA-ITS sequence of Rhizoctonia solani AG 1-ID was determined and compared to those of R. solani AG 1-IA, AG 1-IB, and AG 1-IC. The similarity of the isolates from each AG 1 subgroup was almost identical (99%–100%), whereas it was lower between subgroups (91%–95%) than within subgroups. Phylogenetic analysis indicated that isolates of AG 1-ID and other subgroups were separately clustered. Isolates of R. solani AG 1 were clearly separated from R. solani AG 2-1, AG 4, and binucleate Rhizoctonia AG-Bb and AG-K. These results showed that analysis of the rDNA-ITS sequence is an optimal criterion for differentiating R. solani AG 1-ID from other subgroups of R. solani AG 1.  相似文献   
9.
To investigate the bleaching mechanism, a lignincarbohydrate complex (LCC) model compound, a vinyl ether-type lignin model dimer, and a hexeneuronic acid model compound were treated with dilute sulfuric acid of different pHs. Beech kraft pulp and red pine kraft pulp were also treated with dilute sulfuric acid and then extracted with aqueous alkali. The amount of hexeneuronic acid degradation products in acid effluents and lignin dissolved in alkali effluents were determined. It was found that the benzyl ether-type LCC bond and the vinyl ether bond in lignin were effectively cleaved under the pH where sulfuric acid bleaching of kraft pulp was effective. Hexeneuronic acid group was also effectively degraded during sulfuric acid bleaching. In beech kraft pulp bleaching, both lignin removal and hexeneuronic acid removal contributed to the kappa number reduction. In red pine bleaching, the contribution of hexeneuronic acid removal was negligible, and most of the kappa number reduction was achieved by the lignin removal.Part of this report was presented at the 9th International Symposium on Wood and Pulping Chemistry, Montreal, July 1997  相似文献   
10.
The distributions of ectomycorrhizas and ectomycorrhizal fungal inoculum with soil depth (0–45 cm) were determined in a 40-year-oldBetula platyphylla var.japonica forest. Mycorrhizal and non-mycorrhizal fine roots were measured in each soil core sample that was collected at soil depths of 0–5, 5–10, 10–15, 15–20, 20–25, 30–35, and 40–45 cm. The ectomycorrhizas were mainly distributed (>50%) in the top soil (0–5 cm) of organic forest floor horizons. Below 5 cm the quantity of ectomycorrhizas decreased sharply. The percentage of fine roots which were ectomycorrhizal gradually declined with the depth of soil. The ectomycorrhizal fungal inoculum was evaluated by a bioassay method, measuring the lengths of the entire root system and of the ectomycorrhizal roots of birch seedlings planted in each soil sample. The soil samples were collected from 0–5, 10–15, 20–25, 30–35, and 40–45 cm depths of the soil profile. Ectomycorrhizal formation on birch seedling roots in the bioassay was high in both the soil depth intervals 0–5 cm and 10–15 cm, while the amount was lower in the soil depth interval from 20–45 cm. The results of these investigations show that the amount of the ectomycorrhizas in soil, and the ectomycorrhizal fungal inoculum potential as determined by bioassay, are not always consistent with each other.  相似文献   
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