Harris, Gayle N., Scanlan, David J. and Geider, Richard J.. (2009) Responses of Emiliania huxleyi (Prymnesiophyceae) to step changes in photon flux density. European Journal of Phycology, Vol.44 (No.1). pp. 31-48. ISSN 0967-0262

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Abstract

A non-calcifying strain (Ply 92) of Emiliania huxleyi (Lohman) Hay et Mohler, was subjected to reciprocal step changes of photon flux density (PFD) between 50 and 800 mol photons m-2 s-1 to establish the timescales of photoacclimation. Photoacclimation in E. huxleyi involved adjustment of cellular light harvesting pigment contents, but not cellular ribulose bisphosphate carboxylase-oxygenase (RuBisCO) or cellular RNA contents. There was considerable variability in both the magnitude and the rate of the response of physiological and biophysical variables to the step changes in PFD. The slowest response was observed in cellular chl a content, and the chl a/carbon ratio. Acclimation of these variables appeared to be due to dilution of pigment pools rather than to pigment turnover. Changes in the chl a-specific light absorption coefficient accompanied changes in cellular chl a content. Following the shifts in PFD, the efficiency of excitation energy transfer from the photosystem II antennae to reaction centres II (RCII), as assessed from [image omitted], adjusted within 12 h. The efficiency of charge separation within RCII, as assessed from [image omitted], adjusted on a similar timescale. The overall efficiency of photosystem II (PSII), as assessed from [image omitted]/[image omitted], showed a step response to the change of PFD due to inverse changes in [image omitted], and[image omitted]. Changes in non-photochemical excitation energy quenching were correlated with the relative and absolute abundance of the xanthophyll cycle pigments diadinoxanthin and diatoxanthin, which appeared to be reversibly interconverted with fucoxanthin. Thus, acclimation to PFD involved co-ordinated adjustment of the quantum efficiency of RCII, the efficiency of excitation energy transfer from the light-harvesting pigment bed to RCII, and cellular light absorption on overlapping time scales.

Item Type:	Journal Article
Subjects:	S Agriculture > SB Plant culture Q Science > QH Natural history > QH301 Biology
Divisions:	Faculty of Science > Life Sciences (2010- ) > Biological Sciences ( -2010)
Journal or Publication Title:	European Journal of Phycology
Publisher:	Taylor & Francis Ltd.
ISSN:	0967-0262
Date:	2009
Volume:	Vol.44
Number:	No.1
Number of Pages:	18
Page Range:	pp. 31-48
Identification Number:	10.1080/09670260802233460
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	NERC, NERC
Grant number:	NER/A/S/2003/0041
URI:	http://wrap.warwick.ac.uk/id/eprint/28342

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