虎耳草黑斑病的病原分离鉴定及生物学特性研究

Identification and biological characteristics of pathogen causing black spot disease of Saxifraga stolonifera(L.)Meerb

虎耳草[Saxifraga stolonifera(L.)Meerb.]又名金线吊芙蓉、石荷叶等,是虎耳草科多年生的双子叶草本植物,产于贵州、江苏、浙江等地[1]。虎耳草具有较高的药用价值,有清热、祛湿消肿等功效[2]。从虎耳草中分离得到具有药效成分的就有岩白菜素[3]、没食子酸、槲皮素等[4]。

To identify the pathogen causing black spot disease of Saxifraga stolonifera(L.)Meerb.in the base of Chinese medicinal material(Niudachang Town,Shibing County,Guizhou),we took tissue separation method and tested its pathogenicity according to the Koch’s rule.Combined with morphology and multi-gene(ITS,LSU,RPB2)phylogenetic analysis,we identified Hu42 colony as the pathogen causing the disease.Hu42 colony exhibited highly similar as Leptosphaerulina fungus with an appearance of nearly round,gray-black on the front,light brown on the edge,black on the back,its mycelium was light brown with septal branches and did not produce ascus or ascospores.Based on the phylogenetic tree constructed by multiple genes,the strain was clustered together with Leptosphaerulina americana strain at a support rate of 88%.It was identified as L.americana based on the morphological characteristics and the molecular biology.Moreover,we found that the suitable cultivation conditions of Hu42 are 25℃-28℃,12 h alternating light and dark,the pH at 6-7,soluble starch and yeast extract powder as the carbon and nitrogen sources,and PDA,PSA or beef extract peptone as medium.This study is the first report on black spot disease caused by L.americana on S.stolonifera(L.)Meerb.