The development of fungal fruiting bodies from a hyphal thallus is inducible under  low temperature (cold stress). The molecular mechanism has been subject to  surprisingly few studies. Analysis of gene expression level has become an important  means to study gene function and its regulation mechanism. But identification of  reference genes (RGs) stability under cold stress have not been reported in famous  medicinal mushroom-forming fungi Cordyceps militaris. Herein, 12 candidate RGs had  been systematically validated under cold stress in C. militaris. Three different  algorithms, geNorm, NormFinder...