Author:
Ball MC,Chow WS,Anderson JM
Abstract
Photosynthetic properties were studied in relation to the ionic composition of leaves of Avicennia marina grown in low and high salinity (i.e. 50 and 500 mol m-3 NaCl) nutrient solution containing either 0.01 or 10 mol m-3 K+. Leaves accumulated high concentrations of NaCl, but changes in photosynthesis were associated with changes in leaf K+ concentrations. The effects occurred at two levels. (1) With decrease in leaf K+ from 379 to 167 mol m-3, a 21% decline in light and CO2 saturated rates of oxygen evolution per leaf area was consistent with a 24% decrease in chlorophyll content. (2) Leaves containing only 103 mol m-3 K+ showed drastic loss of light and CO2 saturated photosynthetic capacity (42%) and photochemical dysfunctioning under limiting light conditions as manifest in a 38% decrease in quantum yield. Thylakoids isolated from these low K+ leaves showed no decrease in per chlorophyll concen- trations of photosystem I, cytochrome f/b complex and ATPase, but had 37% fewer atrazine-binding sites (corresponding to photosystem II reaction centres) than those from leaves with higher K+ concentrations. The decline in atrazine-binding sites in isolated thylakoids was sufficient to account for the loss of quantum yield in intact leaves. These results identify the atrazine-binding polypeptide of photosystem II as one site of sensitivity to salinity-induced K+ deficiency.
Subject
Plant Science,Agronomy and Crop Science
Cited by
110 articles.
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