Root Ions Fluxes and Osmolarity Changes in Grass Species Differing in Salinity Tolerance

Abstract

Agricultural areas are increasingly being affected by salt due to irrigation practices and rising levels of salty groundwater. Different plant species have varying degrees of sensitivity to salinity and employ distinct mechanisms to avoid severe damage caused by salt stress. We compared three grass species with different ecological backgrounds, namely Lolium perenne, Festuca rubra, and Puccinellia maritima, in terms of their ability to maintain growth when exposed to salt stress, the extent of Na+-induced K+efflux, and the accumulation of salts in their shoots. Our results demonstrate that the changes in K+and H+fluxes at the root tip induced by NaCl exposure are correlated with the salt tolerance characteristics of these grass species. Specifically, L. perenne exhibited the highest leakage of K+from its roots, the highest accumulation of Na+in its shoots, and the lowest shoot growth under salt stress. On the other hand, P. maritima showed minimal changes in ion fluxes in response to salinity stress. P. maritima maintained the lowest contribution of Na+to the total osmolarity in its shoots and exhibited the least detrimental effect of salt on shoot dry matter. The root cortex including the exodermis and endodermis could be one of the benefit barriers that help defense against salts. In conclusion, root ions fluxes and osmolarity changes in grass species have different salinity tolerance of plants from various habitats. The salt resistance plants restrict leakage of K and exclude Na more effectively. Overall, these results broadened our knowledge of salt resistance in grass species.