[Establishment and optimization of Agrobacterium tumefaciens-mediated genetic transformation system for Polyporus umbellatus].

The unstable quality of Polyporus umbellatus sclerotia during cultivation is the key factor affecting the quality and yield of P. umbellatus sclerotia. In order to provide technical support for obtaining superior P. umbellatus by molecular breeding, the genetic transformation system mediated by Agrobacterium tumefaciens was studied in this paper. A. tumefaciens-mediated method was used to investigate the effects of antibiotic concentration, strain type, A. tumefaciens concentration, receptor material, infection time, co-culture time, and screening conditions on the genetic transformation efficiency of P. umbellatus. The transformants were screened and detected by hygromycin resistance marker genes, polymerase chain reaction(PCR) of specific primers, and fluorescence detection methods. The results showed that the A. tumefaciens GV3101 strain could genetically transfer P. umbellatus mycelium cells, and the optimal conditions for infection were as follows: the A. tumefaciens concentration A_(600 nm)= 0.6, P. umbellatus mycelium cells as receptor material, infection time of 30 min, and co-culture time of 3 days. The two-step screening method involving hygromycin of 9 and 13 μg·mL~(-1 )was the best screening condition. The results of hygromycin resistance screening, PCR detection of specific primers, and fluorescence detection showed that the exogenous gene eGFP had been transferred into the P. umbellatus mycelium cells, integrated into the genome, and successfully expressed. Under optimal conditions, the conversion efficiency could be increased to 2.3%, and the genetic transformation period was shortened from more than 90 days to less than 60 days. This study established and optimized the genetic transformation system of P. umbellatus mycelium cells mediated by A. tumefaciens, laying a foundation for the analysis of the molecular mechanism of P. umbellatus during growth and molecular breeding.