In addition to 6-MSAS and IDH, at least two cytochrome P450 monooxygenase (CYPs) enzymes may be involved in the biosynthesis of patulin in P. expansum. CYPs are versatile biocatalysts that introduce oxygen into a vast range of molecules. They participated in the hydroxylation of two precursors of patulin, m-cresoland m-hydroxybenzylalcohol (Artigot et al., 2009). In the presentstudy, the expression of two cytochrome P450 genes, namelyCYP-1 and CYP-2 were detected after NaHCO3treatment. Results indicated that expression of CYP-1 was up-regulated and that of CYP-2 was down-regulated in NaHCO3-treated spores compared tothe control. The different responses of CYP-1 and CYP-2 indicated that NaHCO3 exerts an extensive influence on spore develop-ment and CYP-2 may conduct a positive regulation in patulin biosynthesis.