Does photodamage to Photosystem II complexes control electron transport during photoinhibition and recovery?
Dmytro Kornyeyev*,1, Barry Logan2, A. Scott Holaday1, 1 Department of Biological Sciences, Lubbock, TX, U.S.A.2 Department of Biology, Brunswick, ME, U.S.A. ABSTRACT- To evaluate the impact of photosystem II (PSII) photoinactivation on chloroplastic electron transport, we assessed the utilisation of excitation energy during and after leaves of Arabidopsis and cotton were exposed to excessive light. PSII photoinactivation was estimated as the level of variable to maximum chlorophyll fluorescence (Fv/Fm). We observed that, during prolonged exposure of Arabidopsis to 1500 mol photons m-2 s-1 for 2.5 h, an increase in the portion of non-photochemical dissipation (NPD) of excitation energy associated with PSII damage (NPDPI) coincided with a decrease in the component of NPD that was readily reversible in darkness (NPDREG) without changes in the over-all level of NPD. The quantum yield for PSII (PSII) did not decline with the increase in NPDPI. To obtain leaves with different levels of PSII
