Over-Expression of Masson Pine PmPT1 Gene in Transgenic Tobacco Confers Tolerance Enhancement to Pi Deficiency by Ameliorating P Level and the Antioxidants

Previously, we cloned the full sequence of masson pine (Pinus massoniana) phosphate transporter gene (PmPT1) from a phosphorus (Pi) deficiency tolerant strain. To further verify whether PmPT1 presumably function in angiosperms, i.e. tobacco, as well as to generate the new germplasm with high tolerance to Pi deficiency, currently, this gene was transferred into tobacco (Nicotiana tabacum) through Agrobacterium-mediated method. PmPT1 chiefly expressed in the roots of the transgenic plants, and considerably promoted the expression of two endogenous phosphate transporter genes of tobacco (NtPT1 and NtPT2) irrespectively of Pi status. Under low Pi conditions, the total P contents of the roots and shoots increased by 33.3% and 25.5%, respectively in L7, and by 30.7% and 23.9%, respectively in L18 in comparison with those of the wild type (WT). Also, the inorganic phosphorus (Pi) content of whole plants in L7 and L18 increased by 42.9% and 42.3%, respectively compared to the WT. The dry weight, contents of chlorophyll, soluble sugar and soluble protein, as well as the activities of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) were significantly elevated, conversely the MDA accumulation was obviously decreased in transgenic lines compared to the WT. Therefore, PmPT1, a phosphate transporter gene of Pht1 family from masson pine might function in tobacco and two overexpressed-PmPT1 transgenic lines substantially enhanced the tolerance of the transgenic tobacco to low-P stress, which was at least chiefly ascribed to the improvement of P accumulation and oxidant alleviation.