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: The constitutive activity of PTOX, uncoupling of thylakoids and the intensive H2O2 formation, already in control Thellungiella plants, rises a question: Whether it could impede a process of carbon assimilation? To verify that, we compared the amounts of proteins at the PSI acceptor side: Rubisco activase (RCA) and Rubisco. A 33 kDa subunit of oxygen evolving complex (PsbO) was used as a reference. Because a growing body of data documented a dual localization of RCA, soluble in the stroma and attached to the thylakoid membranes (Eichelmann et al. 2009, Chen et al. 2010), we looked for these proteins in both of these locations. In leaf extracts as in the thylakoid membranes the level of PSII protein PsbO was similar in both species (Fig. 6). In contrast, the two RCA bands (42 and 47 kDa) were more abundant in leaf extracts from T.s. than in A.t., and difference between the two species became more pronounced when the fraction of TM was considered. This indicates that in T.s. more RCA is attached to the thylakoid membranes. The total level of Rubisco (rbcL 53 kDa band) was similar in A.t. and T.s., however, in T.s. a bigger portion of Rubisco was present in the thylakoid membrane fraction. We suppose that this represents a part of Rubisco currently in contact with a membrane-bound RCA. The initial and total activity of Rubisco was significantly higher in T.s. in comparison to A.t. (Fig. 7). Hence, either a higher activation state of Rubisco or a low level of Rubisco inhibitors might be concluded in this species in comparison to A.t.
Affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387, Kraków, Poland.