TY - JOUR

T1 - A simple chlorophyll fluorescence parameter that correlates with the rate coefficient of photoinactivation of Photosystem II

AU - Hendrickson, Luke

AU - Förster, Britta

AU - Pogson, Barry J.

AU - Wah, Soon Chow

PY - 2005/6

Y1 - 2005/6

N2 - A method of partitioning the energy in a mixed population of active and photoinactivated Photosystem II (PS II) complexes based on chlorophyll fluorescence measurements is presented. There are four energy fluxes, each with its quantum efficiency: a flux associated with photochemical electron flow in active PS II reaction centres (J PS II ), thermal dissipation in photoinactivated, non-functional PS IIs (J NF ), light-regulated thermal dissipation in active PS IIs (J NPQ ) and a combined flux of fluorescence and constitutive, light-independent thermal dissipation (J f,D ). The four quantum efficiencies add up to 1.0, without the need to introduce an 'excess' term E, which in other studies has been claimed to be linearly correlated with the rate coefficient of photoinactivation of PS II (k pi ). We examined the correlation of k pi with various fluxes, and found that the combined flux (J NPQ + J f,D = J pi ) is as well correlated with k pi as is E. This combined flux arises from Fs/F′m, the ratio of steady-state to maximum fluorescence during illumination, which represents the quantum efficiency of combined non-photochemical dissipation pathways in active PS IIs. Since Fs/F′m or its equivalent, J pi , is a likely source of events leading to photoinactivation of PS II, we conclude that Fs/F′m is a simple predictor of k pi.

AB - A method of partitioning the energy in a mixed population of active and photoinactivated Photosystem II (PS II) complexes based on chlorophyll fluorescence measurements is presented. There are four energy fluxes, each with its quantum efficiency: a flux associated with photochemical electron flow in active PS II reaction centres (J PS II ), thermal dissipation in photoinactivated, non-functional PS IIs (J NF ), light-regulated thermal dissipation in active PS IIs (J NPQ ) and a combined flux of fluorescence and constitutive, light-independent thermal dissipation (J f,D ). The four quantum efficiencies add up to 1.0, without the need to introduce an 'excess' term E, which in other studies has been claimed to be linearly correlated with the rate coefficient of photoinactivation of PS II (k pi ). We examined the correlation of k pi with various fluxes, and found that the combined flux (J NPQ + J f,D = J pi ) is as well correlated with k pi as is E. This combined flux arises from Fs/F′m, the ratio of steady-state to maximum fluorescence during illumination, which represents the quantum efficiency of combined non-photochemical dissipation pathways in active PS IIs. Since Fs/F′m or its equivalent, J pi , is a likely source of events leading to photoinactivation of PS II, we conclude that Fs/F′m is a simple predictor of k pi.

KW - Capsicum annuum

KW - Energy flux analysis

KW - Non-photochemical quenching

KW - Photochemistry

KW - Rate coefficient of photoinactivation

KW - Thermal dissipation

UR - http://www.scopus.com/inward/record.url?scp=23444431645&partnerID=8YFLogxK

U2 - 10.1007/s11120-004-6430-4

DO - 10.1007/s11120-004-6430-4

M3 - Article

SN - 0166-8595

VL - 84

SP - 43

EP - 49

JO - Photosynthesis Research

JF - Photosynthesis Research

IS - 1-3

ER -