Coinfection by Different Isolates ofAlternaria alternatain Single Black Spot Lesions of Japanese Pear Leaves

Coinfection by different isolates of Alternaria alternata in single black spot lesions of Japanese pear leaves was detected by restriction fragment length polymorphism (RFLP) analysis of the nuclear ribosomal DNA (rDNA) for differentiation of individual fungal isolates. Mixed-rDNA isolates, whose total DNA contained two types of rDNA units, have been isolated from single black spot lesions of pear leaves in susceptible cultivar Nijisseiki plants. To examine whether mixed-rDNA isolates resulted from coinfection by different rDNA variants, single-spore isolates were prepared from nine mixed-rDNA isolates and subjected to the rDNA RFLP analysis [...]