Photocontrol of the Accumulation of Plastid Polypeptides during Greening of Tomato Cotyledons

Abstract

A pulse of red light acting through phytochrome accelerates the formation of chlorophyll upon subsequent transfer of dark-grown seedlings to continuous white light. Specific antibodies were used to follow the accumulation of representative subunits of the major photosynthetic complexes during greening of seedlings of tomato (Lycopersicon esculentum). The time course for accumulation of the various subunits was compared in seedlings that received a red light pulse 4 h prior to transfer to continuous white light and parallel controls that did not receive a red light pulse. The lightharvesting chlorophyll-binding proteins of photosystem 11 (LHC II), the 33-kD extrinsic polypeptide of the oxygen-evolving complex (OEC1), and subunit 11 of photosystem I (psaD gene product) all increased in the light, and did so much faster in seedlings that received the inductive red light pulse. The red light pulse had no significant effect on the abundance of the small subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), nor on several plastid-encoded polypeptides: the large subunit of Rubisco, the ,B subunit of the CF1 complex of plastid ATPase, and the 43-and 47-kD subunits of photosystem 11 (CP43, CP47). Subunits I (cytochrome b6f) and IlIl (Rieske Fe-S protein) of the cytochrome b6f complex showed a small or no increase as a result of the red pulse. The potentiation of greening by a pulse of red light, therefore, is not expressed uniformly in the abundance of all the photosynthetic complexes and their subunits.

Senescence in wheat leaves: is a cysteine endopeptidase involved in the degradation of the large subunit of Rubisco?

“…After electrophoresis, the gels were stained with Coomassie Brilliant Blue R-250 for visualizing the protein pattern or blotted onto nitrocellulose membranes (0.45 mm supported, Bio Rad) for the detection of specific proteins . The primary polyclonal antibodies were kindly provided by S. Gepstein (Technion-Israel Institute of Technology, Haifa, Israel) against the whole denatured large subunit of Rubisco (Anti-LSU; Pauncz et al 1992), by R. L. Houtz (University of Kensington, Lexington, USA) against the synthetic version of the first 25 amino acids from the N-terminal region of LSU of spinach Rubisco (Anti-N-LSU), by R. M. Wallsgrove (IACR-Rothamsted, Harpenden) against ferredoxin-dependent glutamate synthase (GOGAT) from barley (Marquez et al 1988), by S. Crafts-Brandner (Western Cotton Research Laboratory, Phoenix, Arizona, USA) against purified recombinant tobacco Rubisco activase , and by T. Sugiyama (Nagoya University, Nagoya, Japan) against phosphoenolpyruvate carboxylase (PEPC) from maize (Sugiyama et al 1984). Antibodies against purified glycolate oxidase (GO) from sugar beet were raised as reported previously .…”

Aluminum induced proteome changes in tomato cotyledons

“…2,3 In greening cotyledons, chloroplast proteins for photosynthesis and leaf peroxisomal enzymes in the glycolate pathway for photorespiration are metabolized. [2][3][4] Enzymes involved in regulatory mechanisms such as protein kinases, protein phosphatases, and mitochondrial enzymes are highly expressed. 3,5,6 The chlorotic cotyledons are similar to other chlorotic counterparts in that both contains lower levels of chlorophyll, thus the photosynthetic activities are not as active.…”