Identification and biological characteristics of Fusarium sporotrichioide isolated from Medicago sativa root

The strain BYE27-2-5 isolated from alfalfa( Medicago sativa) with root rot in north China was comprehensively evaluated by analyses of its biological characteristics,morphology,and ITS sequence. The optimum temperatures for mycelium growth,sporulation,and spore germination were 25℃,30℃,and 28℃,respectively. The strain was able to grow in a p H range of 5. 0- 11. 0 and the optimal p H for sporulation and spore germination were 8. 0 and 7. 0,respectively. Alternative light conditions were optimal for mycelial growth whereas complete light conditions were optimal for sporulation and spore germination. Spores germinated most rapidly at 95% relative humidity or in water-drop conditions,and failed germinate at relative humidity levels below 75%. Dextrose peptone medium was the best medium for mycelial growth and spore germination and potato dextrose agar was the best medium for sporulation. The best carbon source for mycelial growth and spore germination was glucose and that for sporulation was sucrose. The best nitrogen source for mycelium growth was peptone and that for spore germination and sporulation was yeast extract. The lethal temperature for mycelia was 54℃( 10 min) and that for spores was 48℃( 10 min). Based on these biological characteristics and the results of an ITS sequence analysis,the isolate was identified as Fusarium sporotrichioide.