Gibberellic Acid and Indole Acetic Acid Improves Salt Tolerance in Transgenic Tomato Plants Overexpressing LeNHX4 Antiporter

Salinity is the major environmental factor that limits plant growth and productivity. High concentrations of Na+ and Cl- ions in soil solution negatively affect K+ uptake and may cause physiological and metabolic disorders, which adversely affect the plant growth and crop yield. In plants, NHX antiporters play an important role in salt tolerance by catalyzing Na+ accumulation in vacuoles. In this work, we studied the effect of exogenous plants hormones auxin (IAA) and gibberellic acid (GA(3)), on salinity tolerance, fruit production and quality in transgenic tomato plants overexpressing LeNHX4 antiporter grown under 125 mM NaCl. Here, we have found that IAA and GA(3) positively affected leaf proline, glucose, soluble proteins and ortho-diphenol. In addition, both hormones increased tomato production and fruit quality parameters. These results suggest that GA(3) and IAA improved salinity tolerance and increased fruit yield and quality, probably by increasing the expression or the activity of LeNHX4 antiporter.