In Vitro-Selected Clones of the Halophyte Arthrocaulon macrostachyum Display Enhanced Salinity Stress Tolerance

Halophytes hold significance for soil desalination and co-cultivation in farming systems. A major impediment to their use is the standardization of their performance, since halophytes are mainly wild plants, in addition to the need for a constant supply of the most suitable species. In this work, using highly salt-tolerant clones of Arthrocaulon macrostachyum obtained previously from in vitro micropropagation and selection, we compared the physiological and biochemical responses of these clones and their wild counterparts to high salinity levels (428 mM NaCl) under glasshouse conditions. In vitro-derived clones displayed a superior biomass production (27%) and higher chloride concentration in the shoot (28%), compared to the wild plants. On the other hand, wild specimens showed more stress symptoms and a less efficient photosynthesis, which was correlated with higher levels of oxidative stress and with a remarkable induction of peroxidase activity. Therefore, a higher incidence of salinity-related oxidative stress in the wild halophytes in comparison to the clones is concluded. This represents the first ex vitro evaluation of halophyte clones selected by means of micropropagation and provides insights into the salinity tolerance mechanisms of A. macrostachyum.