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Light‐dependent, chilling effects on phosphorylation of thylakoid proteins and consequences for associated photochemical activities in maize
Author(s) -
Val Jesus,
Baker Neil R.
Publication year - 1989
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1989.tb05663.x
Subject(s) - thylakoid , phosphorylation , photosystem ii , electron transport chain , protein phosphorylation , biophysics , photosystem i , photosynthesis , chlorophyll fluorescence , photosystem , biology , chlorophyll , phosphoprotein , biochemistry , photochemistry , chloroplast , chemistry , botany , protein kinase a , gene
When maize ( Zea mays L. cv. LG11) leaves are exposed to low temperatures and high light modifications to both photosystem 2 (PS2) and the light‐harvesting chlorophyll a/b protein complex associated with photosystem 2 (LHC2) occur. This study examines the consequences of these modifications for phosphorylation of LHC2 and PS2 polypeptides and the associated changes in electron transport. Maize leaves were chilled at 5°C for 6 h under photon flux densities of 1 500 and 250 μmol m ‐2 s ‐1 . Thylakoids were then isolated from the leaves and their abilities to phosphorylate LHC2 and PS2 polypeptides and modify electron transport activities were determined. Measurements of chlorophyll fluorescence induction in the thylakoids were also made. Thylakoids isolated from leaves chilled under high light and from leaves kept in the ambient growth environment had similar phosphoprotein profiles. However, polypeptide phosphorylation in thylakoids from the chilled leaves did not produce a decrease in PS2 electron transport. Chilling leaves under low light produced a decrease in the ability of isolated thylakoids to phosphorylate PS2, but not LHC2, polypeptides, which was not associated with any change in the phosphorylation‐induced decrease in PS2 electron transport. Chilling under high, but not low, light appears to produce changes in membrane organisation that do not affect the ability of the thylakoids to phosphorylate PS2 and LHC2 polypeptides, but which do prevent the phosphorylation‐induced decrease in excitation energy transfer from LHC2 to PS2.