Reference Gene Selection for Quantitative Real-Time PCR of Mycelia from Lentinula edodes under High-Temperature Stress.

Housekeeping genes are important for measuring the transcription expression of functional genes; 10 traditional reference genes, TUB, TUA, GADPH, EF1, 18S, GTP, ACT, UBI, UBC, and H2A, were tested for their adequacy in Lentinula edodes (L. edodes). Using specific primers, mRNA levels of these candidate housekeeping genes were evaluated in mycelia of L. edodes, which were treated with high-temperature stress at 37°C for 0, 4, 8, 12, 18, and 24 hours. After treatment, expression stability of candidate genes was evaluated using three statistical software programs: geNorm, NormFinder, and BestKeeper. According to geNorm, TUB had the lowest M values in L. edodes strains 18 and 18N44. Using NormFinder, the best candidate reference gene in strain 18 was TUB (0.030), and the best candidate reference gene in strain 18N44 was UBI (0.047). In BestKeeper analysis, the standard deviation (SD) values of UBC, TUA, H2A, EF1, ACT, 18S, and GTP in strain 18 and those of GADPH and GTP in strain 18N44 were greater than 1; thus, these genes were disqualified as reference genes. Taken together, only UBI and TUB were found to be desirable reference genes by BestKeeper software. Based on the results of three software analyses, TUB was the most stable gene under all conditions and was verified as an appropriate reference gene for quantitative real-time polymerase chain reaction in L. edodes mycelia under high-temperature stress.