Abstract:

Flammulina velutipes is one of the most popular edible mushroom species in the world. In this study，3 uracilauxotrophic mutants‘NG1-65’，‘NG1-92’and‘NG1-95’were obtained from the monocaryon 5-fluoroorotic acid（5-FOA）-sensitive F. velutipes strain‘DG1-1’by UV irradiation. UV mutagenesis was conducted under the conditions as following：an irradiation intensity of 10 W，irradiation distance of 15 cm and irradiation time of 12 s. The mutants could grow well in MM media containing 0.05 mmol · L^-1 uridine and 0.5 g · L^-1 5-FOA，but could not grow on MM medium without uridine. PCR analyses revealed that two critical genes pyrF and pyrG in the uridine biosynthetic pathway were disrupted in mutants，probably resulting in the inactivation of related proteins. The survey of the mutation sites suggested that a‘T’inserted the site between the 39th and 40th base of pyrF in strain‘NG1-65’and the 104th base‘C’was changed into‘T’of pyrF in strain‘NG1-95’. The mutant T→C at the site of 236th base was critical to inactive of pyrG in strain‘NG1-92’. The uracil auxotrophs of F. velutipes could be used as a tool for genetic transformation study and strain source identification.

Key words: Flammulina velutipes, ueacil auxotroph, pyrF, pyrG