Cold-hardening-induced resistance to photoinhibition of photosynthesis in winter rye is dependent upon an increased capacity for photosynthesis |
| |
Authors: | Gunnar Öquist Norman P A Huner |
| |
Institution: | (1) Department of Plant Physiology, University of Umeå, S-901 87 Umeå, Sweden;(2) Department of Plant Sciences, The University of Western Ontario, N6A 5B7 London, Ontario, Canada |
| |
Abstract: | Analyses of chlorophyll fluorescence and photosynthetic oxygen evolution were conducted to understand why cold-hardened winter rye (Secale cereale L.) is more resistant to photoinhibition of photosynthesis than is non-hardened winter rye. Under similar light and temperature conditions, leaves of cold-hardened rye were able to keep a larger fraction of the PS II reaction centres in an open configuration, i.e. a higher ratio of oxidized to reduced QA (the primary, stable quinone acceptor of PSII), than leaves of non-hardened rye. Three fold-higher photon fluence rates were required for cold-hardened leaves than for non-hardened leaves in order to establish the same proportion of oxidized to reduced QA. This ability of cold-hardened rye fully accounted for its higher resistance to photoinhibition; under similar redox states of qa cold-hardened and non-hardened leaves of winter rye exhibited similar sensitivities to photoinhibition. Under given light and temperature conditions, it was the higher capacity for light-saturated photosynthesis in cold-hardened than in non-hardened leaves, which was responsible for maintaining a higher proportion of oxidized to reduced QA. This higher capacity for photosynthesis of cold-hardened leaves also explained the increased resistance of photosynthesis to photoinhibition upon cold-hardening.Abbreviations Fm and F'm
fluorescence when all PSII reaction centres are closed in dark- and light-acclimated leaves, respectively
- Fo and F'o
fluorescence when all PSII reaction centres are open in darkness and steady-state light, respectively
- Fv
variable fluorescence (F'm-F'o) under steady-state light conditions
- Fv/Fm
the ratio of variable to maximum fluorescence as an expression of the maximum photochemical yield of PSII in dark-acclimated leaves
- QA
the primary, stable, quinone electron acceptor of PSII
- qN
non-photochemical quenching of fluorescence due to high energy state (pH)
- qp
photochemical quenching of fluorescence
- RH
cold-hardened rye
- RNH
non-hardened rye
This work was supported by a Natural Sciences and Engineering Research Council of Canada (NSERCC) Operating Grant to N.P.A.H. G.Ö. was supported by an NSERCC International Exchange Award and by the Swedish Natural Science Research Council. |
| |
Keywords: | Chlorotophyll fluorescence Cold-hardening Quantum yield Photoinhibition (resistance) Photosystem II |
本文献已被 SpringerLink 等数据库收录! |
|