Overexpression of <i>Leptochloa fusca</i> H ⁺ -pyrophosphatase ( <i>LfVP1</i> ) gene improves salinity and drought tolerance in tobacco

Physiologically, salinity causes osmotic stress due to high solute concentration in soil and disturbs the metabolic and photosynthetic activity of the cells by increasing the toxicity of Na⁺ in the cytoplasm. Plant adaptation to salt stress is characterized by cellular ion homeostasis and vacuolar sequestration of toxic ions from cytosol mediated by H⁺-pyrophosphatase (<i>H</i>^<i>+</i><i>-PPase</i>). The <i>LfVP1</i> gene was cloned under the control of the <i>Gal1</i> promoter for yeast transformation and the <i>CaMV35S</i> promoter for tobacco transformation. Yeast supplementation assay demonstrated that <i>ena1</i> and <i>ena1:nhx1</i> yeast mutants, transformed with <i>LfVP1</i> genes, could only be able to partially complement the effect of NaCl and hygromycin in the presence of a functional Na⁺/H⁺ antiporter gene. Transgenic tobacco plants transformed with the <i>LfVP1</i>gene had significantly higher photosynthetic levels, stomatal conductivity, relative water content, membrane stability index, and negative osmotic potential under osmotic stress compared to wild-type plants (WT). Seeds of the transgenic line <i>LfVP1</i>-PB4 (single gene insertion) and WT were germinated on the MS₀ medium supplemented with 200 and 250 mM NaCl. Transgenic plants showed better growth and tolerance to salinity stress than WT plants. Our findings indicate that the overexpressing <i>LfVP1</i> gene has a potential role in enhancing the abiotic stress tolerance in crops such as rice, wheat, and maize.