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

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.