Developmental acquisition of salt tolerance in the halophyteAtriplex halimus L. is related to differential regulation of saltinducible genes

Abstract The present study investigated the developmental

tolerance of Atriplex halimus to osmotic and/or

ionic stress. A. halimus was exposed to NaCl (0, 100, 250

and 400 mM), KCl (0, 100, 250 and 400 mM) and sorbitol

(0, 200, 500 and 800 mM) at the level of germination,

seedling emergence and vegetative stages. The response of

A. halimus to different salts was stage dependent especially

to NaCl that had a remarkable effect on A. halimus growth

at each stage. At the germination stage, the growth

reduction could be attributed to osmotic effect and HRD

may have a role in that osmotic sensitivity. At this stage,

the accumulation of Na? into vacuole could be a strategy

for alleviating the osmotic effect. At the seedling emergence

stage, the inhibition of growth could be mainly

attributed to the ionic effect that may have resulted from

excessive accumulation of Na? along with inconsistent

regulations of Na? manipulating genes. A. halimus at the

vegetative stage was an obligate halophyte with regulated

mechanisms of tolerance to both ionic and osmotic components

of salt stress. A. halimus exhibits glycophytic

features at the early growth stages but it is an obligate

halophyte at the vegetative stage