Leaf sodium accumulation facilitates salt stress adaptation and preserves photosystem functionality in salt stressed Ocimum basilicum

In this study, plant growth, water relations, ABA levels, ion accumulation patterns and chlorophyll fluorescence were functionally linked to salt stress tolerance of two basil cultivars (Napoletano and Genovese) with different stress sensitivity levels. Plants were treated with salty water at 0, 100 and 200 mM of NaCl. Potential photosynthetic efficiency, non-photochemical quenching and upregulation of photodamage protection by D1 protein revealed higher salt tolerance in Genovese plants, which also resulted in improved water balance and photosynthesis preservation. Upon stress, these plants accumulated also lower ABA and were less affected than Napoletano by salinity in terms of biomass production. Genovese plants were able to upregulate the expression of genes for ROS scavenging and cation transport. These results along with the ability of GEN plants to accumulate larger amount of Na⁺ in the leaf tissue indicate that this cultivar was better suited to partially use Na⁺ as osmoticum.