Acclimation of Tomato Leaves to Changes in Light Intensity; Effects on the Function of the Thylakoid Membrane

Abstract

Davies, E. C, Chow, W. S., Le Fay, J. M. and Jordan, B. R. 1986. Acclimation of tomato leaves to changes in light intensity: effects on the function of the thylakoid membrane.—J. exp. Bot. 37: 211-220. When young tomato plants grown in high light (400 /anol quanta m 2 c ' low light (100/unol quanta m~ s~' the rate of dark re-oxidation of Q~, the first quinone electron acceptor of photosystem II, was decreased within 1-2 d. In contrast, the amount of coupling factor CF,, assayed by its ATPase activity, decreased more gradually over several days. The total chlorophyll content per unit leaf area remained relatively constant, although the chlorophyll a/chlorophyll b ratio declined. When young tomato plants grown in low light were transferred to high light, the ATPase activity of isolated thylakoids increased markedly within 1 d of transfer. This increase occurred more rapidly than changes in chlorophyll content per leaf area. In addition, in vivo chlorophyll fluorescence induction curves indicate that forward electron transfer from Q occurred more readily. The functional implications of these changes are discussed. Key words—Tomato, leaves, light intensity, thylakoid membrane. Correspondence to: Glasshouse Crops Research Institute, Worthing Road, Littlehampton, West Sussex BN17 6LP, U.K.