Ectopic expression of ibPDS gene enhanced tolerance to oxidative stress in transgenic tobacco plants

The phytoene desaturase (PDS) gene, which is associated with carotenoid biosynthesis, was isolated from sweet potato (Ipomoea batatas L.). The open reading frame of IbPDS gene is comprised of 1719-base pairs and encodes a polypeptide of 573 amino acid residues. The deduced IbPDS protein sequence was homologous with that of other PDS proteins of various plant species. Also, the IbPDS gene appears to be a member of multiple gene families and further, the differences in the copy numbers among the five cultivars were considered to lead to differences in tuber color and carotenoid contents. Investigation of the mRNA expression of IbPDS revealed the greatest expression in the leaf tissue of sweet potatoes under both normal conditions and methyl viologen (MV) stress. The IbPDS cDNA was introduced to Nicotiana tabacum cv. Xanthi under the control of the CaMV 35S promoter using Agrobacterium-mediated gene transfer techniques, thereby resulting in an increase in tolerance to MV (2, 10, and 50 µM). These results occurred owing to the elevated antioxidant capacity of carotenoids in transgenic plants.