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Targeted Disruption of a Melanin Biosynthesis Gene Affects Conidial Development and UV Tolerance in the Japanese Pear Pathotype of Alternaria alternata

January 1999 , Volume 12 , Number  1
Pages  59 - 63

Chie Kawamura , Takashi Tsujimoto , and Takashi Tsuge

Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan

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Accepted 29 September 1998.

Structural analysis of the BRM2 gene involved in melanin biosynthesis of the Japanese pear pathotype of Alternaria alternata suggested that this gene encodes 1,3,8-trihydroxynaphthalene reductase. Targeted disruption of the BRM2 gene did not affect pathogenicity, vegetative growth, or the number of conidia produced. Targeted disruption, however, did reduce conidial size and septal number, suggesting that melanin is associated with conidial development. The conidia of brm2 mutant transformants were more sensitive to UV light than those of the wild type, demonstrating that melanin confers UV tolerance.

Additional keywords: appressorium, host-specific toxins.

© 1999 The American Phytopathological Society