The kinetics of P‐700+ reduction in leaves : a novel in situ probe of thylakoid functioning
Harbinson, J. ; Hedley, C.L. - \ 1989
Plant, Cell & Environment 12 (1989)4. - ISSN 0140-7791 - p. 357 - 369.
electron transport - irradiance response - PSI - P‐700 - quantum efficiency
Abstract. The half time (t1/2) of the reduction of P‐700+ in the millisecond time frame is known to be limited by the reaction between plastoquinol and the cytochrome cytb6f complex. This is considered to be the rate limiting reaction of thylakoid electron transport and measurements of it provide a means of analysing how thylakoid election transport is regulated in vivo. The half time for the reduction of photochemically oxidized P‐700 has been measured in vivo using absorbance changes around 820 nm. The results showed that t1/2 is independent of irradiance and decreases as photosynthetic induction progresses. Even with a constant t1/2 the quantum efficiency of PSI declined as irradiance increased. The significance of the concept of photosynthetic control of electron transport is discussed in the light of these observations.
The use of light‐induced absorbance changes at 820 nm to monitor the oxidation state of P‐700 in leaves
Harbinson, J. ; Woodward, F.I. - \ 1987
Plant, Cell & Environment 10 (1987)2. - ISSN 0140-7791 - p. 131 - 140.
820 nm light‐induced absorbance change - photosynthesis - photosystem I - P‐700
Abstract The use of the light‐induced absorbance change at 820 nm (ΔA 820) to monitor the oxidation and reduction of P‐700 in irradiated leaves is examined. Results obtained from leaves irradiated with a range of wavelengths of light, poisoned with DCMU, or lacking PS I, are consistent with the proposition that the light‐induced ΔA 820 can be used to monitor P‐700 oxidation in leaves.