Identification of fungal species associated with apple canker in Tarim Basin China

Abstract

Apple canker has decreased yields of the economically important apple (Malus domestica Borch) crop in China in recent years. Pathogen identity is highly challenging and the disease is poorly understood. Specimens of 339 fungi were isolated from apple trees in the primary apple-producing region in the Tarim Basin during the current study. A total of 9 species of Cytospora and 5 species of Botryosphaeriaceae were identified by morphological observation and multi-locus phylogenetic analyses (ITS, ACT, TEF, and TUB for Cytospora; ITS, TEF, and TUB for Botryosphaeriaceae). Cytospora pyri from the Cytospora genus was the dominant species causing apple canker in the Tarim Basin. Cytospora melnikii, Cytospora tritici, Cytospora euonymina, Diplodia seriata, and Botryosphaeria dothidea have been described as the cause of apple canker in China. Apple (Red Fuji) branches were utilized to assess the pathogenicity of 24 representative fungal isolates from the 14 species and branches from seven distinct woody plants, Korla pear, walnut, Chinese date, Xinjiang poplar, sand jujube, Populus euphratica, and willow, were utilized to analyze the host range. The main pathogenic fungal species of apple canker around the Tarim Basin were identified and biological characteristics explored. Pathogen diversity and regional source diversity were assessed with host range and pathogenicity. The aim was to provide a theoretical foundation for the prevention and treatment of apple canker.