Cloning and Function Identification of a Phytoene Desaturase Gene from Eucommia ulmoides

The phytoene desaturase (PDS) encodes a crucial enzyme in the carotenoid biosynthesis pathway. Silencing or inhibiting PDS expression leads to the appearance of mottled, chlorosis, or albino leaves. In this study, the CDS sequence of EuPDS (Eucommia ulmoides Phytoene Desaturase) was first cloned and then PDS was silenced in Nicotiana benthamiana. Result showed the expression level of EuPDS in leaves was higher than that in the roots and stems. In N. benthamiana leaves, which were treated by Agrobacterium for 24 h, photo-bleaching was shown on the fresh leaves one week after injection and the transcript level of PDS was down-regulated during the period of emersion. This suggested that EuPDS could silence PDS of N. benthamiana, so as to cause the phenotype of leaf whitening. PDS is the main reporter gene involved in virus-induced gene silencing (VIGS). This study offered molecular evidence for identifying PDS gene involved in Carotenoid’s biosynthesis pathway and the regulation networks in E. ulmides. It also laid a useful foundation for study on leaf discoloration mechanism of other woody plants.