Overexpression of potato StPIP2-7 ameliorates PEG-induced osmotic stress in transgenic Arabidopsis plants

Plants expressing the potato PIP2-7 gene encoding a plasma membrane intrinsic protein were subjected to osmotic stress and evaluated for their tolerance. Compared to wild type (WT) plants under osmotic stress, three PIP Arabidopsis lines exhibited higher chlorophyll content, improved stomatal conductance, less electrolyte leakage, lower malondialdehyde (MDA) accumulation, and higher proline concentrations. PIP plants accumulated elevated amounts of mRNA transcripts of four main antioxidant enzymes: ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR) and superoxide dismutase (SOD). A significant change in the expression of five major stress-response genes was also observed in PIP plants, suggesting that potato PIP gene overexpression promoted Arabidopsis’s osmotic stress resistance. Fluorescence kinetic analyses of chlorophyll-a showed that PIP plants had enhanced photochemical efficiency of photosystem II (PSII) and performance indices (PIs). A comparison of quantum yields and efficiencies under stress showed that PIP plants were more photosynthetically active than WT plants. Consequently, these results suggest that PIP may prove useful for developing stress-tolerant crops in the future.