Abstract:

The aim of this study was to isolate and characterize the causal pathogen of root rot from Juema （Potentilla anserina）. Samples were collected from the roots of Juema plants with root rot at the Juema artificial planting base in Huangyuan County， Qinghai Province， China. Strain D2 isolated from diseased samples was comprehensively evaluated in terms of its pathogenicity， morphology， rDNA-ITS sequence， and biological characteristics. The isolated strain D2 was identified as Fusarium perseae， a pathogenic fungus of Juema causing root rot. The optimum temperatures for mycelium growth， sporulation， and spore germination of strain D2 were 25， 30 and 25 ℃， respectively. The lethal temperature for mycelia was 64 ℃ （10 min）， and constant light conditions were not optimal for mycelial growth. Strain D2 was able to grow in a pH range of 5.0 to 12.0， and weak alkali conditions were more conducive to its growth and sporulation. The strain was able to use a variety of carbon and nitrogen sources， with fructose as the optimal carbon source and beef extract as the optimum nitrogen source. Some carbon and nitrogen sources promoted the production of a green pigment in strain D2. The types of nitrogen sources were ranked， from most to least efficient utilization by D2， as follows： Organic nitrogen>nitrate nitrogen>ammonium nitrogen. Ammonium nitrogen was more conducive to sporulation. These findings indicate that more attention should be paid to pastoral hygiene and water/fertilizer management to prevent the occurrence and spread of root rot at the Juema artificial planting base. These results provide a reliable basis for the diagnosis and prevention of the root rot in Juema.

Key words: Potentilla anserina, Fusarium spp., pathogenic fungi, biological characteristics