The Physiological Mechanism of Improved Formaldehyde Resistance in Petunia hybrida Harboring a Mammalian cyp2e1 Gene

Cytochrome P450 CYP2E1 is mainly present in hepatocytes in the livers of mammals, where it plays an important role in the metabolism of xenobiotic organic substances. Previous studies showed that transgenic petunia (Petunia hybrid) plants harboring a mammalian cyp2e1 gene (designated cyp2e1-transgenic petunia) exhibited increased resistance to formaldehyde stress. In this study, we used cyp2e1-transgenic petunia plants to analyze physiological indexes related to formaldehyde stress responses. The results indicated that under formaldehyde stress, the malondialdehyde content in cyp2e1-transgenic petunia plants was lower than in β-glucuronidase gene (gus)-transgenic and wild-type petunia plants. The activities of both superoxide dismutase and peroxidase in the cyp2e1-transgenic plants were higher than in gus-transgenic and wild-type plants. The alcohol dehydrogenase activity was slightly increased and more glutathione was consumed. Additionally, under formaldehyde stress, the levels of plant hormones including indole-3-acetic acid, zeatin and abscisic acid in cyp2e1-transgenic petunia plants displayed decreasing trends, whereas the level of gibberellic acid displayed an increasing trend. In contrast, the indole-3-acetic acid, zeatin and abscisic acid levels in gus-transgenic and wild-type petunia plants displayed increasing trends, whereas the gibberellic acid level displayed a decreasing trend. At 72 h after incubation of 0.5 g of cyp2e1-transgenic petunia plants in 40 mL of treatment solution containing formaldehyde at 50 mg · L−1, the formaldehyde content remaining in the treatment solution was close to zero while approximately half of original formaldehyde remained in the treatment solutions containing gus-transgenic and wild-type petunia plants.