Effects of salt stress on low molecular antioxidants and redox state of plastoquinone and P700 in Arabidopsis thaliana (glycophyte) and Eutrema salsugineum (halophyte)

Abstract

The effects of NaCl treatment were analysed in two species of considerably different resistance. In glycophyte, the content of ascorbate decreased but lipophilic antioxidants (α-tocopherol, plastochromanol, and hydroxy-plastochromanol) increased due to 150 mM NaCl. In halophyte, 300 mM NaCl caused a significant increase in hydrophilic antioxidants (ascorbate, total glutathione) but not in the lipophilic antioxidants. The redox states of plastoquinone (PQ) and P700 were also differently modulated by salinity in both species, as illustrated by an increased oxidation of these components in glycophyte. The presented data suggest that E. salsugineum was able to avoid a harmful singlet oxygen production at PSII, which might be, at least in part, attributed to the induction of the ascorbate-glutathione cycle. Another important cue of a high salinity resistance of this species might be the ability to sustain a highly reduced states of PQ pool and P700 under stress, which however, drastically affect the NADPH yield.