Simultaneous expression of SbCPN10L and SbNHX1 enhances salt and drought stress tolerance in transgenic tobacco, associated with improved photosynthetic performance

The NHX1 is well-known antiporter for alleviating the salt stress through upregulation. Present study reports on the physiochemical performance of transgenic tobacco overexpressing a strongly downregulated SbCPN10L gene under salt stress in the presence of a strongly upregulated SbNHX1 gene. Results report on individual as well as simultaneous expression of both SbCPN10L and SbNHX1 together. Interesting results were observed in the transgenic lines overexpressing SbCPN10L and in the double transgenic overexpressing both genes. Transgenic plants had higher seed germination, and early growth metrics like seedling height, biomass, relative water content, stress tolerance index, and osmotic adjustment as compared to wild-type (WT) control and vector control (VC) plants under salt and drought stress. Similarly, biochemical analysis indicated an increased accumulation of compatible solutes such as soluble sugars, starch, amino acids, and polyphenol in transgenic tobacco exposed to stress. The enhanced membrane stability, reduced electrolyte leakage, lower levels of hydrogen peroxide and reactive oxygen species (ROS) production were linked to enhanced accumulation of compatible solutes in transgenic tobacco. Long-term growth analysis in soil supported the enhanced stress tolerance in transgenic plants, particularly for the double transgenic tobacco. Transgene improved the cellular and osmotic fitness of tobacco under stress condition, which is associated with improved photosynthetic performance in transgenic lines overexpressing both SbCPN10L and SbNHX1 gene. Collectively, the results indicate that SbCPN10L and SbNHX1 have complementing roles in stress resilience and their expression adds up to be favorable physiology for plants under stress conditions.