Changes in D1-protein turnover and recovery of photosystem II activity precede accumulation of chlorophyll in plants after release from mineral stress

Abstract

Abstract.After seven weeks of a combined magnesium and sulphur deficiency, spinach (Spinacea oleracea L.) plants showed a substantial accumulation of inactivated photosystem II (PSII) centres as indicated by a 40% decrease of the chlorophyll (Chl) fluorescence parameter Fv/Fm (Fv being the yield of variable fluorescence and Fm the yield of maximal fluorescence when all reaction centres are closed) together with a severe loss of leaf Chl content of 75%. The responses of the photosynthetic apparatus were examined when the deficient plants were transferred back to a rich nutrient medium. During the first 24 h of the recovery phase, thylakoid protein synthesis measured as incorporation of [14C]leucine per unit of Chl increased substantially. The synthesis rate of the DI reaction-centre polypeptide of PSII, which in the deficient plants was reduced to 50% of the non-deficient control, was stimulated eight-to ninefold. Dl-protein content, which in the deficient plants was reduced to 40% of the non-deficient control, started to increase 2 d later. Thus, D 1-protein degradation was also enhanced. The increased Dl-protein turnover led to a rapid repair of the existing PSII centres as indicated by the rise of Fv/Fm. It was completed at day 7 of the recovery phase. At day 2 of the recovery phase, the synthesis of other thylakoid proteins such as the D2 protein, cytochrome b559, CP 47 and the 33-kDa polypeptide of the water-splitting system, became stimulated. This process resulted in an accumulation of new PSII centres. During the first week, formation of new PSII centres was not associated with an increase in leaf Chl content. The Chl content of the recovering leaves only started to increase when the ratio of PSII polypeptides versus LHCII (light-harvesting complex of PSII), which was substantially diminished in the deficient plants, became comparable to that of the control. The recovery process was accompanied by substantial changes in thylakoid protein phosphorylation. Their relevance to thylakoid protein turnover and stability is discussed.

Physiological characterisation of magnesium deficiency in sugar beet: acclimation to low magnesium differentially affects photosystems�I and II

“…6b; see Appendix). These data are consistent with a previous study of spinach suffering from Mg and S deficiency (Dannehl et al 1996). Feedback regulation of photosynthesis could also occur from redox signals.…”

“…Different substitutions have been applied in previous studies, resulting in variation in the concentrations of major elements (Terry and Ulrich 1974;Fischer and Bremer 1993;Dannehl et al 1996;Fischer et al 1998;Sun et al 2001). In order not to alter the anion/cation balance, equimolecular amounts of sodium sulfate were used, as in Cakmak et al (1994aCakmak et al ( , 1994b.…”

“…The relative content of thylakoid proteins per unit chlorophyll (Chl) was determined immunologically by western blotting. Thylakoids were solubilized as described in Dannehl et al (1996), and polypeptides were separated by denaturing polyacrylamide gel (12%) electrophoresis using a Mini-Protean II electrophoresis cell (Bio-Rad). Proteins were transferred onto nitrocellulose membrane Hybond-C extra (Amersham Life Science) by electroblotting at 400 mA for 3 h. Primary antibodies against PsbA (dilution 1:2,000) purchased from Agrisera (Sweden) were detected using an anti-chicken IgG-alkaline phosphatase conjugate detection system (Sigma).…”

Synthesis of the sulfur amino acids: cysteine and methionine

“…At least partially the pale phenotype of sulfur deficiency is based upon reduced Cys synthesis, caused by sulfide limitation in higher plants. As a result of diminished de novo synthesis of Cys turnover of chlorophyll binding protein of Photosystem II (D1-protein) is significantly shifted to degradation (Dannehl et al 1996;Godde and Hefer 1994). In particular the availability of amino acids including cysteine can contribute to limit the synthesis of D1-protein in plastids, since D1-protein assembles co-translational into Photosystem II, whereby regulation at the post-translational level is diminished (Zhang et al 1999).…”

Organ-specific effects of dark treatment on photosynthesis and the expression of photosynthesis-related genes

“…The photosynthetic apparatus is highly dynamic and able to respond to environmental stresses, including changes in the quality and quantity of incident radiation (Szabo et al 2005, Chowdhury et al 2009), mineral starvation (Dannehl et al 1996), drought and extreme temperatures (Smart 1994, Humbeck et al 2007, Zhang et al 2009). The transfer of individual intact or detached leaves, as well as whole plants, to darkness is a widely used experimental approach to study the molecular basis of the stress response and the adaptive mechanisms allowing plants to survive the adverse conditions (Biswal and Biswal 1984, Oh et al 1996, Weaver et al 1998).…”