Steady-state and induction kinetics of the photosynthetic electron transport related to donor side oxidation and acceptor side reduction of photosystem 1 in sunflower leaves

Title:

Steady-state and induction kinetics of the photosynthetic electron transport related to donor side oxidation and acceptor side reduction of photosystem 1 in sunflower leaves

Creator:

Laisk, A., Oja, V., and Heber, U.

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:b88a6666-3db9-4617-8b88-5a802d7a25c1
uuid:b88a6666-3db9-4617-8b88-5a802d7a25c1
urnnbn:urn:nbn:cz:aba007-000fc0

Type:

model:internalpart and TEXT

Format:

print

Description:

The photosynthetic CO2 exchange rate, chlorophyll fluorescence and P700 oxidation (absorption at 830 nm) were recorded in attached leaves of sunflower plants grown in soil by irradiance 460 pmol m'2 s‘i. Ehiring the photosynthesis in 510 cm^ m*3 CO2, 1 % O2, photosystem 1 (PS 1) effíciency was ahnost totally determined by the donor side oxidation under all irradiances. Fluorescence data showed that this control was exercised mostly by ApH-dependent plastoquinol oxidation. At 1.5 pM intracellular [CO2], the PS 1 reduction level on the acceptor side became signifícant and increased as [CO2] -> 0. ApH controlled the electron flow when the rate exceeded the value of 50 pmol(e‘) m'2 s‘i, which was close to the rate supporting photorespiration and CO2 reassimilation at CO2 compensation concentration in 21 % O2. The ApH ability to control the electron transport rate adequately prevented electron carriers reduction at PS 1 acceptor side, with stomata dosed under stress. When the low CO2 oř carbon reduction enzymes inactivation restricted the electron transport downstream of PS 1, open PS 1 centres (oxidised on acceptor sides) percentage declined in proportion to CO2 uptake rate. This makes us doubt the common belief that the rapid electron transport in photosynthesis involves interconnected, mobile electron carrier pools of plastocyanin and ferredoxin (Fd). Rather, the implications are explored in terms of supercomplexes involving cytochrome b(Jf, PC, PS 1, Fd and Fd-NADP reductase.

Language:

Multiple languages

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Coverage:

449-463 and 25-39

Source:

Photosynthetica | 1992 Volume:27 | Number:4

Harvested from:

CDK

Metadata only:

false