The Growth Characteristic of Mycelia and Conidia for Mycocentrospora acerina

Mycocentrospora acerina is the pathogen causing round spot in Panax Notoginseng, but it is not entirely clear on its biological characteristic yet. In this study, a large number of conidia were induced by in-vitro inoculation on the Panax leaf, and the effect were observed on the mycelia and colony growth, conidia germination under different carbon and nitrogen sources, pH and temperature, with crossing method and hanging drop method. The results showed that M. acerina could grow on 10 different kinds of solid and liquid media. Potato dextrose agar was the best solid medium, and potato sucrose was the best liquid media. The fungus could utilize monosaccharides, polysaccharides and alcohols as carbon sources, and the optimum carbon sources was maltose. The utilization of organic nitrogen source was significantly higher than that of inorganic nitrogen source, the optimum nitrogen sources was yeast extract. The fungus mycelia grew well between 4 and 28℃ with optimum of 20℃, and it could not grow when the temperature was higher than 30℃. In addition, pH 4~13 with optimum of pH 6.5 was suitable for its growth, and the light could promote mycelia growth. The conidia could germinate at 4~32℃, pH 3~12 and RH 75%~100%, with the optimal at 18℃, pH 6. It was found that the germination rate of the conidia favorite higher humidity.0.5% peptone was the most conducive solution to the conidia germination. The light could also promote the germination of conidia. The lethal temperature for the growth of mycelia and conidia were both 55℃, which demonstrated that M. acerina have a strong ability to adapt the environment, but it is sensitive to temperature, and suitable for growth under low temperatures.