1990 Fiscal Year Final Research Report Summary
Structural and Functional Analysis of Linear Plasmid DNAs of Plant Pathogenic Fungus
| Project/Area Number |
63480039
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
植物保護
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| Research Institution | Tohoku University |
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Principal Investigator |
HAYASHIDA Teruyoshi Tohoku University Associate Faculty of Agriculture Professor, 農学部, 助教授 (20189476)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Hideki Tohoku University Tutor Faculty of Agriculture, 農学部, 助手 (20197164)
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| Project Period (FY) |
1988 – 1990
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| Keywords | Plasmid of plant pathogenic fungus / Rhizoctonia solani / pRS64 plasmid / Hairpin loops structure / Sequence homology among plDNAs / Chromosomal DNA |
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| Research Abstract |
1. Plasmid-like DNA (plDNA) was found in 48 out of 114 field isolates of Rhizoctonia solani. These 48 isolates were distributed as follows among the nine anastomosis groups (AG) and intraspecific groups (ISG) recognized among Japanese isolates of R. solani : 0 in AG-1 (sasakii type), 1 in AG-1 (web-blight type), 0 in AG-2-1, 11 in AG-2-2 (rush type), 10 in AG-2-2 (root rot type), 10 in AG-3, 8 in AG-4, 4 in AG-5 and 4 in AG-6. Each isolate carried one, two or three plDNAs identified by gel electrophoresis. Electron microscopic analysis revealed that all these plDNAs were linear molecules. The sequence homology among plDNAs found in representative isolates was examined by Southern blot analysis, using nick-translated plDANs as probes. Considerable sequence homology was observed among plDNAs obtained from isolates within the same AG and ISG. The plDNAs occurring in the isolates of AG-2-2 were classified into two groups on the basis of the sequence homology.
2. Three linear DNA plasmids were found in isolate RI-64 of anastomosis group 4 (AG-4) of Rhizoctonia solani. These plasmids, designated pRS64-1, -2, and -3, possessed the same size of 2.7 kb. Restriction mapping and Southern hybridization anlysis of pRS64-1, -2, and -3 revealed the presence of homologous regions at both termini. The plasmid DNAs were resistant to both 3'-exonuclease and 5'-exonuclease even after treatment with protease K or alkali. The length of both terminal fragments that were generated by restriction endonuclease digestion was doubled under the denaturation condition, indicating that the linear plasmid DNAs have hairpin loops at both termini. Southern blotting analysis of total DNA showed the presence of two types of dimeric forms of pRS64 DNA. One is a head-to-head dimer and the other is a tail-to-tail dimer. The role of these unique DNA structures in replication of th
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