Ectopic expression of an apple cytochrome P450 gene MdCYPM1 negatively regulates plant photomorphogenesis and stress response in Arabidopsis

Cytochrome P450s play an important role in plant growth and are involved in multiple stresses response. However, little is known about the functions of cytochrome P450s in apple. Here, a Malus × domestica cytochrome P450 monooxygenase 1 gene, MdCYPM1, was identified and subsequently cloned from apple 'Gala' (Malus × domestica). To verify the functions of MdCYPM1, we generated transgenic Arabidopsis plants expressing the apple MdCYPM1 gene under the control of the Cauliflower mosaic virus 35S promoter. Four transgenic lines (#3, #5, #7 and #8) were selected for further study. The transgenic plants exhibited a series of skotomorphogenesis phenotypes relative to wild-type controls, such as reduction of the chlorophyll, anthocyanins content and hypocotyls elongation. In addition, overexpression of MdCYPM1 influenced auxin transport and flowering time in transgenic Arabidopsis. Furthermore, MdCYPM1 expression was induced by salt and mannitol treatments, and the transgenic plants were negatively regulated by salinity and osmotic stresses during germination. These results suggest that MdCYPM1 plays a vital role in plant growth and development.