Abstract：
The present study aims to explore the potential of a plasma-membrane localized PIP2-type aquaporin protein sourced from the halophyte Salicornia brachiata to alleviate salinity and water deficit stress tolerance in a model plant through transgenic intervention. Transgenic plants overexpressing SbPIP2 gene showed improved physio-biochemical parameters like increased osmolytes (proline, total sugar, and amino acids), antioxidants (polyphenols), pigments and membrane stability under salinity and drought stresses compared to control plants [wild type (WT) and vector control (VC) plants]. Multivariate statistical analysis showed that, under water and salinity stresses, osmolytes, antioxidants and pigments were correlated with SbPIP2-overexpressing (SbPIP2-OE) plants treated with salinity and water deficit stress, suggesting their involvement in stress tolerance. As aquaporins are also involved in CO2 transport, SbPIP2-OE plants showed enhanced photosynthesis performance than wild type upon salinity and drought stresses. Photosynthetic gas exchange (net CO2 assimilation rate, PSII efficiency, ETR, and non-photochemical quenching) were significantly higher in SbPIP2-OE plants compared to control plants (wild type and vector control plants) under both unstressed and stressed conditions. The higher quantum yield for reduction of end electron acceptors at the PSI acceptor side [Φ( R0 )] in SbPIP2-OE plants compared to control plants under abiotic stresses indicates a continued PSI functioning, leading to retained electron transport rate, higher carbon assimilation, and less ROS-mediated injuries. In conclusion, the SbPIP2 gene functionally validated in the present study could be a potential candidate for engineering abiotic stress resilience in important crops.
摘要：
本研究旨在探索源自盐生植物的质膜定位的PIP2型水通道蛋白通过转基因干预减轻模型植物的盐度和水分亏缺胁迫耐受性的潜力。过表达SbPIP2基因的转基因植物显示出改善的生理生化参数，例如渗透压增加（脯氨酸，总糖,和氨基酸)，抗氧化剂（多酚），与对照植物[野生型（WT）和载体对照（VC）植物]相比，在盐度和干旱胁迫下的色素和膜稳定性。多元统计分析表明,在水和盐度胁迫下，渗透压,抗氧化剂和色素与经过盐度和水分亏缺胁迫处理的SbPIP2过表达（SbPIP2-OE）植物相关，表明他们参与了压力承受能力。由于水通道蛋白也参与二氧化碳的运输，SbPIP2-OE植物在盐度和干旱胁迫下显示出比野生型增强的光合作用性能。光合气体交换(净CO2同化率，PSII效率，ETR,在未胁迫和胁迫条件下，与对照植物（野生型和载体对照植物）相比，SbPIP2-OE植物中的非光化学猝灭）均显着更高。与非生物胁迫下的对照植物相比，SbPIP2-OE植物中PSI受体侧[Φ（R0）]减少末端电子受体的量子产率更高，表明PSI功能持续，导致保留的电子传输速率，更高的碳同化，和较少的ROS介导的损伤。总之,在本研究中功能验证的SbPIP2基因可能是重要作物非生物抗逆性工程的潜在候选者。
