Morphological and Molecular Identification of Colletotrichum gloeosporioides Causing Walnut Anthracnose in Shandong Province, China

摘要

Walnut anthracnose is a wide-spread and destructive disease in China. The aetiological agent was isolated from typical anthracnose lesions of infected fruits, leaves and shoots, and morphological characteristics and phylogenetic analysis based on ITSwere used to identify the pathogen of walnut anthracnose. The result showed that colonies of these isolates could be divided into three types by conidia shape: cylindrical, with an average size of 10.4-15.6x5.4 um; cylindrical, but occasionally slightlyacute on the base, the average size of 11.7x4.6 um; cylindrical, slightly curved middle or dumbbell shaped, the average size of 15.0x6.4 um. The appressoria are dark brown or light brown, with ovoid, suborbicular, crack leafy and irregular form, the sizeis different with an average of 10.2x7.3 um. Phylogenetic analysis using ITS showed that all isolates form a compact cluster with Colletotrichum gloeosporioides. Hence, based on morphological and molecular data, it could be concluded that C. gloeosporioides is the pathogen causing walnut anthracnose in Shandong province, China.