A novel pathogenic Colletotrichum species for rhizome rot disease of Polygonatum kingianum / 中国中药杂志

Rhizome rot disease is one of the main disease of planted Polygonatum kingianum. In this study, six strains of pathogenic fungus was isolated from P. kingianum samples with rhizome rot disease collected from six counties in Yunnan province. Its pathogenicity was confirmed by inoculation to healthy P. kingianum rhizome according to Koch's postulates. The colonies of the isolated fungi on potato dextrose agar(PDA) were orange with abundant crescentic conidia which were eseptate with a mean size of 19. 3-24. 9 μm×5. 2-5. 9 μm and a L/W ratio of 3. 4-4. 5. There was an oil ball in the center of the conidium. It's easy to see setae on PDA colony.The phylogenetic tree based on ITS, GAPDH, CHS-1, HIS3, ACT, and TUB2 sequences by maximum likelihood(ML) method indicated that the pathogenic fungus for P. kingianum rhizome rot disease was clustered into the clade of Colletotrichum spaethianum species complex, and was close to C. spaethianum. However, there were some differences in morphological and genetic characteristics between the pathogenic fungus and C. spaethianum. Therefore, the pathogenic fungus for rhizome rot disease of P. kingianum was identified as a new Colletotrichum species named C. kingianum. The disease spreads primarily due to the plantation of infected seedlings of P. kingianum. It is necessary to choose healthy seedlings and take rigorous disinfection measures for the disease prevention.

Gray mold disease of Paris polyphylla var. yunnanensis and its pathogen identification / 中国中药杂志

Gray mold disease is one of the most important diseases of planted Paris polyphylla var. yunnanensis, the disease appeared primarily as blossom blights and fruit rots, but also as stem rots, leaf rots.In this study, the pathogenetic fungi was isolated from plant tissue or sclerotia that covering the fruit of diseased P. polyphylla var. yunnanensis, the pathogen was certified according to Koch's Postulation. The pathogen produced abundant black, irregular sclerotia on surface of diseased plants and potato dextrose agar. The conidiophores and clusters of oval conidia resembled a grape-like cluster, the size of conidia was 9.70-13.70 μm [average of (11.32±0.82)μm]×7.05-9.12 μm [average of (8.24±0.48)μm], the microconidia produced on potato dextrose agar were spherical,and the size was （3.34±0.31） μm,the pathogen was identified as Botrytis sp based on morphological characteristics. The DNA sequence analysis of the G3PDH, HSP60, RPB2 genes placed the pathogen in a single clade that outside defined species of Botrytis, so the pathogen could be identified as a new species of Botrytis. The pathogen requires 20 °C, pH 8, darkness or low light condition for the best growth.