Isolation of Pathogenicity Mutants of Fusarium oxysporum f. sp. melonis by Insertional Mutagenesis |
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Authors: | lori INOUE Toshiaki OHARA Fumio NAMIKI Takashi TSUGE |
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Institution: | (1) Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464–8601, Japan, JP;(2) Kyushu National Agricultural Experiment Station, Nishigoshi-machi, Kikuchi-gun, Kumamoto 861–1192, Japan, JP |
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Abstract: | Restriction enzyme-mediated integration (REMI) mutagenesis was used to isolate mutants of Fusarium oxysporum f. sp. melonis impaired in pathogenicity. The race 2 strain Mel02010 was transformed with linearized pSH75, conferring resistance to hygromycin
B, with or without the enzyme used to linearize the plasmid. Addition of restriction enzymes did not affect the transformation
frequency. A total of 2929 REMI transformants were tested for pathogenicity to three melon cultivars, Amus, Ogon 9 and Ohi.
The race 2 strains are pathogenic to Amus and Ogon 9, but not to Ohi. Of 43 transformants with reduced pathogenicity on susceptible
melon cultivars, 12 mutants were examined in detail for pathogenicity, vegetative growth and integrative mode of pSH75. The
levels of pathogenicity varied among these mutants. Two mutants (B48 and B137) almost completely lost pathogenicity to both
susceptible cultivars, and the others had reduced pathogenicity. Mutants B48, B241, B886 and X36 were also impaired in vegetative
growth. Mutant B809 was a biotin auxotroph. By DNA gel blot analysis, nine mutants were found to contain a single copy of
the transformation vector. These mutants may thus be useful in isolating genes involved in pathogenicity.
Received 22 December 2000/ Accepted in revised form 16 April 2001 |
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Keywords: | : Fusarium oxysporum f sp melonis pathogenicity restriction enzyme-mediated integration |
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