Biological effects and ISSR analysis of 60Co γ-irradiation on edible mushroom mycelia

Mycelia of Agaricus bitorquis, Flammulina velutipes and Pleurotus eryngii were irradiated by 60Co γ-rays at the dose of 0, 200, 500 and 800 Gy. The results showed that irradiation inhibited their mycelia growth positively. Of the three edible mushroom, Agaricus bitorquis was the most sensitive one to irradiation, its mycelia died at the dose of 800 Gy. Germination rate, growth rate and vigor of all mycelia irradiated with un-lethal doses increased along with the times of transfer of culture. Electrical conductivity (EC) analysis showed that irradiation increased EC of leaching solution of mycelia positively. The EC of leaching solution of mycelia of Flammulina velutipes and Pleurotus eryngii irradiated with 500 Gy, Agaricus bitorquis irradiated with 200 Gy, were significantly higher than CK. ISSR analysis revealed that 60Co γ irradiation effect on DNA variation of Agaricus bitorquis, Flammulina velutipes and pleurotus eryngii mycelia in varying degrees. Number of polymorphic bands changed after irradiation. Flawing bands and increasing bands were observed in amplified bands of 14 selected ISSR primers. The ISSR variation rates of Agaricus bitorquis for 200 Gy and 599 Gy treatments were 33.3% and 50.5%; the ISSR variation rates of Flammulina velutipes for 200 Gy, 500 Gy and 800 Gy treatments were 2.3%, 2.3% and 3.1%, that of Pleurotus eryngii were 8.6%, 13.4% and 20.0%. It is possible to use 60Co γ irradiation as a mutagen to screen new mushroom varieties. (authors)