title: Increased capacity for synthesis of the D1 protein and of catalase at low temperature in leaves of cold-hardened winter rye (Secale cereale L.).
abstract: The effect of low temperature on protein synthesis, particularly the synthesis of the photolabile proteins D1 of photosystem II and catalase (EC 1.11.1.6), was compared in non-hardened leaves (NHL) and cold-hardened leaves (CHL) of winter rye (Secale cereale L.). At 4 degrees C, both the uptake of L-[(35)S]methionine into leaf sections and its incorporation into proteins were reduced, relative to 25 degrees C. However, much lower reductions were observed in CHL than in NHL. In particular, the proportion of the L-[(35)S]methionine uptake incorporated into membrane proteins at 4 degrees C was considerably higher in CHL than in NHL. At 25 degrees C, the incorporation of L-[(35)S]methionine into both the D1 protein and catalase was lower in CHL than in NHL, in accord with a slower light-induced turnover in CHL. At 4 degrees C, the incorporation into the D1 protein and catalase was, however, much higher in CHL than in NHL, indicating that their de novo synthesis was less suppressed by the low temperature. The results indicate that cold-acclimated leaves had an improved ability to repair the photolabile proteins D1 and catalase at low temperature, relative to NHL. mRNAs for the D1 protein and for leaf catalase were not increased in CHL, relative to NHL. The superior capacity of CHL for repair at low temperature must result from posttranscriptional mechanisms. The translational efficiency of the catalase mRNA was similarly increased in both NHL and CHL during 7-h exposures to high light at 4 degrees C, while the amounts of the catalase transcript declined under these conditions. However, during a recovery period at 22 degrees C, subsequent to an exposure of NHL to 4 degrees C and high light, transient increases of the D1 and catalase mRNAs were observed.
authors.affiliation: Botanisches Institut, Goethe-Universität, Postfach 11 19 32, 60054 Frankfurt am Main, Germany.
authors.forename: William
authors.initials: W
authors.lastname: Shang
authors.forename: Matthias
authors.initials: M
authors.lastname: Schmidt
authors.forename: Jürgen
authors.initials: J
authors.lastname: Feierabend
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D002374:Catalase / Q000096:biosynthesis*; D003080:Cold Temperature; D008027:Light; D008715:Methionine / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000096:biosynthesis*; D045332:Photosystem II Protein Complex; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012434:Secale / Q000235:genetics / Q000378:metabolism*; D013462:Sulfur Radioisotopes
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D012333:RNA, Messenger; D013462:Sulfur Radioisotopes; D008715:Methionine; D002374:Catalase