Overexpression of PDX-II gene in potato (Solanum tuberosum L.) leads to the enhanced accumulation of vitamin B6 in tuber tissues and tolerance to abiotic stresses

Abstract

Vitamin B6 is a vital metabolite required for living organisms as a cofactor in several metabolic biochemical reactions and recognized as a potent antioxidant molecule which modulates the expression of the proteins responsible for the scavenging of cellular reactive oxygen species. It is well established that the microorganisms and plants can synthesize the B6 de novo, therefore, all the animals including humans must acquire it from the plant dietary resources. However, the bioavailability of the vitamin in the edible portions of the commonly consumed plants is insufficient to meet the daily recommended doses. Genetic engineering techniques have proven successful in increasing the vitamin B6 content in the model plants. Present study describe the development of transgenic potato (Solanum tuberosum L. cv. Kufri chipsona) overexpressing key vitamin B6 pathway gene, the PDXII (NCBI database Ref. ID- NM_125447.2) isolated from Arabidopsis thaliana under the control of CaMV 35S constitutive promoter. The stable integration and expression of transgene in the transgenic lines were confirmed by PCR, Southern blot and RT-PCR analysis. Transgenic tubers exhibited considerably improved vitamin B6 accumulation (up to 107-150%) in comparison to the untransformed controls potato. This increase in vitamin B6 was also correlated with the increased mRNA expression of PDXII gene. The prominent increase in the B6 content of transgenic potato was also associated with the capability to survive under abiotic stresses, therefore, the transgenic lines were able to withstand various abiotic stresses imposed by salinity (NaCl) or methyl viologen (MV). We thus demonstrated that overexpression of PDXII gene under the control of a constitutive promoter enhanced the accumulation of the vitamin B6 which also augmented the tolerance under various abiotic stresses in potato (Solanum tuberosum L.).

Keywords: Abiotic stress tolerance; Bio-fortification; Crop biotechnology; Oxidative stress; PDX II gene; Vitamin B6.