Premium
The rate coefficient of repair of photosystem II after photoinactivation
Author(s) -
He Jie,
Chow Wah Soon
Publication year - 2003
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2003.00107.x
Subject(s) - irradiance , photosystem ii , photosynthesis , biophysics , chemistry , botany , biology , biochemistry , optics , physics
During photosynthesis, photoinactivation and repair of photosystem II (PSII) occur simultaneously, resulting in a net loss of functional PSII under a given irradiance. This study determines the rate coefficients for the partial processes, allowing the calculation of the partial rates at any concentration of functional/non‐functional PSII. The rate coefficient of photoinactivation was obtained from the onset of photoinactivation of PSII in leaf segments of Capsicum annuum L. in the absence of repair, and was in turn used to obtain the rate coefficient ( k r ) of repair of PSII when repair was occurring. The value of k r was found to be near maximum at an irradiance as low as 29 µmol photons m −2 s −1 and peaked at or somewhat above the growth irradiance; however, it declined on further increasing the irradiance, possibly due to oxidative stress. The value of k r was considerably decreased by elevating the CO 2 to about 1%, particularly at low irradiance, probably due to acidification of the stroma to a pH outside the range that is optimal for protein synthesis. The method of determining k r is convenient to apply, not relying on radiolabelling and pulse‐chase experiments.