Seven new species of Alternaria (Pleosporales, Pleosporaceae) associated with Chinese fir, based on morphological and molecular evidence

Chinese fir (Cunninghamia lanceolata) is a special fast-growing commercial tree species in China and has significant ecological and economic value. However, it experienced damage from leaf blight caused by pathogenic fungi of the genus Alternaria. To determine the diversity of Alternaria species associated with leaf blight of Chinese fir in China, infected leaves were collected from five major cultivation provinces (Fujian, Henan, Hunan, Jiangsu and Shandong provinces). A total of 48 fungal strains of Alternaria were obtained. Comparison of morphology and phylogenetic analyses, based on nine loci (ITS, SSU, LSU, GAPDH, RPB2, TEF1, Alt a1, endoPG and OPA10-2) of the representative isolates as well as the pairwise homoplasy index tests, revealed that the fungal strains belonged to seven undescribed taxa of Alternaria, which are described here and named as Alternaria cunninghamiicola sp. nov., A. dongshanqiaoensis sp. nov., A. hunanensis sp. nov., A. kunyuensis sp. nov., А. longqiaoensis sp. nov., A. shandongensis sp. nov. and A. xinyangensis sp. nov. In order to prove Koch’s postulates, pathogenicity tests on detached Chinese fir leaves revealed significant pathogenicity amongst these species, of which A. hunanensis is the most pathogenic to Chinese fir. This study represents the first report of A. cunninghamiicola, A. dongshanqiaoensis, A. hunanensis, A. kunyuensis, A. longqiaoensis, A. shandongensis and A. xinyangensis causing leaf blight on Chinese fir. Knowledge obtained in this study enhanced our understanding of Alternaria species causing leaf blight on Chinese fir and was crucial for the disease management and the further studies in the future.