Thellungiella salsuginea TsPIP1;1 and TsTIP1;1 enhanced the salt tolerance of transgenic rice

ObjectivesTo better understand the regulatory roles of aquaporins in plants in response to salt stress and provide a theoretical support for the application of aquaporin genes in molecular breeding of salt tolerant crop, two aquaporins of Thellungiella salsuginea, plasma membrane intrinsic protein TsPIP1;1 and tonoplast intrinsic protein TsTIP1;1, were investigated by profiling the physiological responses in the transgenic rice under salt stress.

MethodsWild type (WT) and T3 generations of the transgenic rice carrying the TsPIP1;1 and TsTIP1;1 were subjected to hydroponic solution with 0, 100 and 200 mmol/L NaCl in greenhouse, respectively. After one-week’s salt treatments, some important physiological parameters such as the photosynthetic rates, plant height, biomass, relative water contents, water loss rates and the contents of Na⁺ and K⁺ were determined.

ResultsUnder 200 mmol/L NaCl treatment, compared with the wild type, the transgenic rice exhibited higher biomass and relative water contents, and lower water loss rates and osmotic potentials, and demonstrated lower contents of Na⁺ and higher contents of K⁺ in roots and shoots and thus leading to lower Na⁺/K⁺ ratios. The transgenic rice maintained stronger net photosynthetic rate, stomatal conductance, transpiration rate and water use efficiency. Compared with the wild type, in 200 mmol/L NaCl treatment, the shoot heights in the transgenic lines TsTIP-5, TsTIP-7 and TsPIP-19 were respectively increased by 8.2%, 11.6% and 4.9%, and plant dry weights were increased by 17.9%, 23.9% and 16.9%, while the Na⁺/K⁺ ratios of shoots were reduced by 24.3%, 24.4% and 24.8%, and the Na⁺/K⁺ ratios of roots were decreased by 29.6%, 27.5% and 32.4%. The osmotic potentials were significantly depressed by 18.3%, 19.4% and 30.3%, the relative water contents were increased by 5.8%, 5.5% and 5.4%, and the net photosynthetic rates were increased by 50.4%, 78.8% and 56.2%.

ConclusionsThe transgenic rice of carrying the TsPIP1;1 and TsTIP1;1 genes had better growth development, and enhanced the salt tolerance by increasing the photosynthesis and respiration, decreasing the Na⁺/K⁺ ratio, participating in cell osmotic adjustment and improving the water holding capacity in plant cells.