Enhanced chloroplastic generation of H2O2 in stress-resistant Thellungiella salsuginea in comparison to Arabidopsis thaliana.
Bottom Line: In order to find some basis of salinity resistance in the chloroplastic metabolism, a halophytic Thellungiella salsuginea was compared with glycophytic Arabidopsis thaliana.Salinity treatment (0.15 and 0.30 M NaCl for A.t. and T.s., respectively) led to a decrease in ratios of chl a/b and F730 /F685 .In A.t., a salinity-driven enhancement of YII and NPQ was found, in association with the stimulation of H2 O2 production from PQ pool.
Affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387, Kraków, Poland.Show MeSH
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Mentions: Leaves of control Arabidopsis and Thellungiella plants were characterized by a similar chlorophyll a+b content amounting to 1.02 ± 0.05 and 1.10 ± 0.04 µg mg−1 FW in A.t. and T.s., respectively. However, the composition of chl was slightly different, as demonstrated by a higher chl a/b ratio in T.s. amounting to 2.92, in comparison to 2.52 in A.t. (Fig. 1A). After the salinity-treatment amounts of chlorophyll were 1.1 ± 0.04 and 1.3 ± 0.07 in A.t. and T.s., respectively, while, the chl a/b ratio declined in both species to 2.31 and 2.2, in A.t. and T.s., respectively. To get a further insight into the relative sizes of PSI and PSII antennae, we monitored the chlorophyll fluorescence emission at 77 K. In this method, PSI- and PSII-associated chlorophyll antennae are reflected by the emission peaks at 730 and 685 nm, respectively. In control conditions, the proportion of chlorophyll associated with PSI in T.s. was significantly higher than in A.t. (Fig. 1B). A bigger contribution of PSI antenna may result from a permanent change in the thylakoid architecture or from a temporary migration of part of LHCII (light harvesting-complex II) antennae to PSI (state 1 to state 2 transition) driven by a reduced plastoquinone (PQ) pool. To resolve that, we also analyzed changes in the F730/F685 during night–day transition, however, no differences between the two species were detected (data not shown).
Affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387, Kraków, Poland.