Fredersdorf, Jana and Bischof, Kai (2007) Research note: Irradiance of photosynthetically active radiation determines ultraviolet-susceptibility of photosynthesis in Ulva lactuca L.(Chlorophyta). Phycological Research, 55 (4). pp. 295-301. DOI https://doi.org/10.1111/j.1440-1835.2007.00474.x.

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Abstract

The respective ratio of photosynthetically active to ultraviolet radiation is of crucial importance to results obtained in ultraviolet (UV)‐research on photoautotrophic organisms. Specimens of the green macroalga Ulva lactuca L. were exposed to a constant irradiance of UV‐radiation at increasing irradiances of photosynthetically active radiation (PAR). The effects of experimental irradiance and spectral composition on photoinhibition of photosynthesis and its recovery were monitored by chlorophyll fluorescence measurements and the activity of the xanthophyll cycle was assessed by high performance liquid chromatography‐(HPLC) based pigment analysis. Results indicate a UV‐induced delay in recovery from PAR‐induced photoinhibition and a deceleration of violaxanthin conversion within the xanthophyll cycle due to the presence of UV‐radiation. Also the concentration of the protective pigment lutein increased considerably and could be indicative of the existence of an additional light‐protective mechanism, as, for example, the lutein‐epoxid cycle in Ulva. In total, results clearly show that the extent of UV‐induced inhibition of photosynthesis to be found in UV‐exposure experiments is highly dependent on the irradiance of background photosynthetically active radiation: with increasing irradiance of PAR the UV‐effects were diminished. Exemplified by the green algae Ulva lactuca this study demonstrates the crucial importance of the ratios of PAR:UV applied in UV‐research, particularly when conducting laboratory experiments in an ecological context.

Document Type:	Article
Programme Area:	UNSPECIFIED
Research affiliation:	Ecology > Algae and Seagrass Ecology
Refereed:	Yes
Open Access Journal?:	No
DOI:	https://doi.org/10.1111/j.1440-1835.2007.00474.x
ISSN:	1322-0829
Date Deposited:	28 Feb 2020 12:23
Last Modified:	26 Mar 2024 13:30
URI:	http://cris.leibniz-zmt.de/id/eprint/3469

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