Abstract:

Objective: In this study, we isolated and characterized the causal agents of witches' broom disease on 5 bamboo species of non-Phyllostachys, and analyzed the morphological features and culture characteristics of the pathogens, which would provide a scientific basis for identifying of the pathogen, controlling the witches' broom disease of bamboo, and determining the phylogenetic relationship of Clavicepitaceae. Method: The pathogens of witches' broom disease were isolated from the infected tissues of five bamboo species of non-Phyllostachys in Hangzhou of Zheijiang and Xishuangbanna, Yunnan through the conventional tissue isolation approach. The species identification was conducted based on morphological methods combined with molecular biology. The morphology and conidia size of the pathogens were determined by microscope, and the phylogenetic relationships of Clavicipitaceae were investigated based on the ITS rDNA and LSU rDNA sequences. Result: The morphological structure of the pathogens isolated from Semiarundinaria sinica, Bashania fargesii and Pseudosasa amabilis var. tenuis were similar to Aciculosporium take. The conidia of pathogenic fungus formed a pale yellow colony with uneven fold, slightly glossy surface and irregular edge on PDA plate. The conidia of pathogenic fungus was needle shape, (22.4-52.0) μm×(2.2-6.0) μm in size. The mycelia of pathogenic fungi isolated from the infected tissues of Dendrocalamopsis stenoaurita and Dendrocalamus strictus formed round colony with smooth surface and regular edge on PDA plate. The pathogen produced short rod-like conidia after 72 days of culture, and the size of the conidia was (5.4-10.5) μm×(1.2-2.8) μm. The sequence analysis and phylogenetic analysis based on ITS rDNA and LSU rDNA showed that the pathogenic fungus isolated from S. sinica, B. fargesii and P. amabilis var. tenuis were clustered with A. take with 99% bootstrap support, and the pathogenic fungus isolated from D. stenoaurita and D. strictus were clustered with Heteroepichloë bambusae with 100% bootstrap support. Conclusion: The causal agent of witches' broom disease of S. sinica, B. fargesii and P. amabilis var. tenuis is A.take, which is closely related to the genus Claviceps.The causal agent of witches' broom disease of D. stenoaurita and D. strictus. is H.bambusae, which is closely related to the genus Balansia, but distantly related to the genus Epichlo.

Key words: Dendrocalamopsis, Bashania, witches' broom disease, phylogenetic tree