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Two linear plasmids in mitochondria of Fusarium solani f. sp. cucurbitae
Abstract:
Two linear plasmid-like DNAs designated pFSC1 (9.2 kbp) and pFSC2 (8.3 kbp) were found in an isolate of the plant pathogenic fungus Fusarium solani f. sp. cucurbitae race 1. The plasmids were maternally inherited and copurified with mitochondrial DNA obtained from a mitochondria-enriched cell fraction suggesting that they are located in mitochondria. The plasmids did not share extensive sequence similarity. No homology was detected between either plasmid and the nuclear or mitochondrial genome when cloned plasmids were used as probes in Southern hybridization analyses. The fungus was cured of plasmids by ethidium bromide treatment. Compared to the plasmid-containing isolate, plasmid-cured derivatives had reduced pathogenicity on a susceptible plant host, Cucurbita maxima "Pink Banana."
Insights
Two novel linear plasmids, pFSC1 and pFSC2, were identified in the fungus Fusarium solani. Curing these plasmids reduced the fungus
Area of Science:
- Mycology
- Molecular Biology
- Plant Pathology
Background:
- Fusarium solani f. sp. cucurbitae race 1 is a plant pathogenic fungus.
- Fungal isolates can harbor extrachromosomal DNA elements like plasmids.
- The role of such elements in fungal pathogenicity is often unclear.
Purpose of the Study:
- To characterize novel plasmid-like DNAs found in Fusarium solani.
- To investigate the potential role of these plasmids in fungal pathogenicity.
Main Methods:
- Isolation and characterization of plasmid-like DNAs (pFSC1, pFSC2).
- Localization studies via co-purification with mitochondrial DNA.
- Sequence similarity analysis and Southern hybridization against nuclear and mitochondrial genomes.
- Plasmid curing using ethidium bromide treatment.
- Pathogenicity assays on Cucurbita maxima.
Main Results:
- Two linear plasmid-like DNAs, pFSC1 (9.2 kbp) and pFSC2 (8.3 kbp), were identified.
- These plasmids are maternally inherited and appear to be located in mitochondria.
- No significant sequence similarity was found between the plasmids or with the host genome.
- Ethidium bromide treatment successfully cured the fungus of both plasmids.
- Plasmid-cured fungal derivatives exhibited reduced pathogenicity on susceptible squash plants.
Conclusions:
- Fusarium solani harbors unique mitochondrial plasmids (pFSC1, pFSC2).
- These plasmids are not homologous to the nuclear or mitochondrial genomes.
- The presence of these plasmids is linked to the pathogenicity of Fusarium solani.