Journal Article

Seasonal acclimation of photosystem II in <i>Pinus sylvestris</i>. I. Estimating the rate constants of sustained thermal energy dissipation and photochemistry

Albert Porcar-Castell, Eija Juurola, Eero Nikinmaa, Frank Berninger, Ingo Ensminger and Pertti Hari

in Tree Physiology

Volume 28, issue 10, pages 1475-1482
Published in print August 2008 | ISSN: 0829-318X
Published online August 2008 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/28.10.1475
Seasonal acclimation of photosystem II in Pinus sylvestris. I. Estimating the rate constants of sustained thermal energy dissipation and photochemistry

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Summary

Acclimation of the partitioning of absorbed light energy in Photosystem II (PSII) between photochemical and non-photochemical processes includes short-term adjustments that are rapidly reversed in the dark and seasonal acclimation processes that are unaffected by dark acclimation. Thus, by using dark-acclimated leaves to study the seasonal acclimation of PSII, the confounding effect of short-term adjustments is eliminated. The maximum quantum yield of photochemistry, estimated by chlorophyll fluorescence analysis as Fv/Fm, where Fv = (FmFo), and Fm and Fo are maximum and minimum chlorophyll fluorescence, respectively, has been widely used to follow the seasonal acclimation of PSII, because it is measured in dark-acclimated leaves. Seasonal changes in Fv/Fm can be caused by adjustments in either the photochemical capacity in PSII, or the capacity of thermal dissipation in PSII, or both. However, there is a lack of chlorophyll fluorescence parameters that can distinguish between these processes. In this study, we introduce two new parameters: the rate constants of sustained thermal energy dissipation (kNPQ) and of photochemistry (kP). We estimated kNPQ and kP from dark-acclimated Fo and Fm measured during spring recovery of photosynthesis in Scots pine (Pinus sylvestris L.) trees. We suggest that kNPQ and kP be used to study the mechanisms underlying the observed seasonal acclimation in PSII, because these parameters provide quantitative data that complement and extend Fv/Fm measurements.

Keywords: chlorophyll concentration; chlorophyll fluorescence; energy partitioning; Scots pine

Journal Article.  0 words. 

Subjects: Plant Sciences and Forestry

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