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Effects of prolonged freezing stress on the photosynthetic apparatus of moderately hardy leaves as assayed by chlorophyll fluorescence kinetics
Author(s) -
SCHULTEIS C.,
SANTARIUS K. A.
Publication year - 1989
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1989.tb01644.x
Subject(s) - thylakoid , spinacia , photoinhibition , chlorophyll fluorescence , photosynthesis , electron transport chain , photosystem ii , frost (temperature) , botany , chemistry , horticulture , biology , biophysics , chloroplast , biochemistry , materials science , composite material , gene
Moderately frost‐hardy leaves of the wintergreen broadleaf woody shrubs Pyracantha coccinea and Ligustrum ovalifolium and the winter annual herb Spinacia oleracea were subjected to extended freezing stress up to 15 d at temperatures 2–8°C above the mean lethal temperature (LT 50 ). After thawing, the fast kinetics of in vivo chlorophyll fluorescence of photosystem II (PSII) and the potential of linear photosynthetic electron transport of isolated thylakoid membranes was measured at room temperature. The lower the minimum freezing temperature and the longer the time of exposure, the greater was the suppression of the fluorescence signals of the leaves and decrease of the electron transport capacity of the thylakoid membranes. The pattern of inactivation of PSII ‐mediated electron flow, i.e. inhibition of photoreaction to photochemistry and/or electron donation to the photochemical reaction, during long‐term freezing at temperatures somewhat above the LT 50 of the leaves was similar to that observed earlier after relatively brief exposure of leaves and isolated thylakoid membranes to more severe freezing stress. As injury occurred during freezing in complete darkness, it is likely that prolonged winter stress under natural environmental conditions causes changes in the photosynthetic apparatus of moderately hardy leaves which are not due to photoinhibition.