Effects of ABA and NaCl on physiological responses in selected bryophyte species

Abstract

The effects of NaCl and abscisic acid (ABA) on selected bryophyte species were studied. Two phylogenetically unrelated halophyte mosses, namely, Entosthodon hungaricus (Boros) Loeske and Hennediella heimii (Hedw.) R.H. Zander in addition to one model non-halophyte moss, Physcomitrella patens (Hedw.) Bruch & Schimp, were selected to compare the variability in certain biochemical and physiological parameters under salt-stress alone and salt-stress upon ABA pretreatment. The results showed different patterns of effects from ABA in all three of the studied species, as well as no common response to salt stress. In general, all of the tested species reacted to exogenous ABA, which definitely contributed to changes observed in morphological development under salt stress, and to the functioning of the salt-tolerance mechanisms. Physcomitrella patens proved to be a salt-tolerant species. Although it is not ecologically classified as a halophyte, these results highlighted that various stress resistance pathways are supported by similar reactions to different stresses. Significant differences in stress tolerance were documented between the two bryo-halophytes tested by comparing biochemical and physiological parameters. Our findings suggest that different salt-stress-tolerance strategies characterize these two species, both enhanced by exogenous ABA.