Alternaria malicola sp. nov., a New Pathogen Causing Fruit Spot on Apple in China

Abstract

Alternaria spp. are pathogens of several diseases that pose significant threats to apple production. Several putative Alternaria sp. isolates were obtained from lesions of a disease commonly referred to as black dot on apple fruit in Shaanxi Province, China. Pathogenicity tests using mycelial plugs and conidial suspensions indicated that this isolate could cause leaf blotch, as well as moldy core and black dot on fruit. On the basis of sequence analysis of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), RNA polymerase second largest subunit, and translation elongation factor 1-α, an isolate clustered with the Alternaria sect. Ulocladioides. By combining GAPDH, major allergen Alta1, mating type protein 1-2-1, and the AGA1 gene sequence analysis and morphological description, the isolates were identified as a new species named Alternaria malicola. Our finding expands the documented diversity of apple pathogens within the genus Alternaria and clarifies the taxonomy of the pathogen assemblage that may be associated with three apple diseases.