ABSTRACT
Osmoregulation in higher plants is defined by Blum1 as follows: As water is being removed from the cell, osmotic potential is reduced due to the simple effect of solute concentration. In prokaryotes the term osmoregulation refers to active processes carried out during adaptation to the osmotic strength of the environment. In prokaryotes considerable progress in elucidating the mechanisms involved in osmoregulation has been made by the characterization of mutants with altered solute synthesis and/or transport properties, clearly illustrating that the process of osmoregulation is under genetic control. The capacity for accumulating organic solutes is a general feature of halophytic higher plants, but species differ markedly with respect to the types of organic osmolytes accumulated. The degree to which different plant species can tolerate high concentrations of salt is clearly under genetic control. The widespread occurrence of orders of flowering plants with halophytic species is “indicative of a polyphyletic origin perhaps involving relatively few changes in the genome”.
