[Identification and biological characterization of a fungal strain causing root rot of Rehmannia glutinosa]

Root rot is a serious soil-borne disease in the field of Rehmannia glutinosa with continuous cropping obstacle, which se-riously affects the quality and yield of Rehmanniae Radix. In this study, a fungal strain causing root rot of R. glutinosa was isolated from the rhizosphere soil of R. glutinosa planted in Wenxian county, Henan province and identified based on the morphological characteristics and molecular evidence. The pathogenicity and biological characteristics of the isolate were studied. The sequence alignments of RPB2 and EF1-α genes and the phylogenetic analysis identified the isolate as Fusarium falciforme. This pathogen has not been reported to cause root rot in R. glutinosa, being a new pathogen. The optimal culture conditions of the strain were PDA medium, 28 ℃, full light. The strain was not sensitive to pH. The strain experienced rapid mycelial growth with sucrose, maltose, and glucose as the carbon sources. Although the mycelial growth of the strain slowed down when sodium nitrate, potassium nitrate, ammonium sulfate, ammonium nitrate, and urea were used as nitrogen sources, the mycelial density was greater than that of the Czapek negative control group. The mycelial growth was the fastest when sodium nitrate was used as the nitrogen source. The lethal temperatures for mycelia and spores of the strain were 69,61 ℃, respectively. The findings provide a basis for the prevention and control of root rot in R. glutinosa.