Differences in acclimation potential of photosynthesis in seven isolates of the tropical to warm temperate macrophyte Valonia utricularis (Chlorophyta)

• Published in: Phycologia
• Main Authors: Eggert, Anja, Visser, Ronald J. W., Van Hasselt, Philip R., Breeman, Anneke M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2006
• Subjects: light-harvesting; photosynthesis; thermal acclimation; Valonia utricularis; PHOTOSYSTEM-II; XANTHOPHYLL-CYCLE; ECOTYPIC DIFFERENTIATION; MARINE-PHYTOPLANKTON; THERMAL-ACCLIMATION; CHLORELLA-VULGARIS; ELECTRON-TRANSPORT; GROWTH TEMPERATURE; CHONDRUS-CRISPUS; MAIZE LEAVES; Pacific; Northeast Atlantic
• Online Access: http://hdl.handle.net/11370/b1ef3c5c-538b-41f3-9aaa-c2a282b43b6f; https://research.rug.nl/en/publications/differences-in-acclimation-potential-of-photosynthesis-in-seven-isolates-of-the-tropical-to-warm-temperate-macrophyte-valonia-utricularis-chlorophyta(b1ef3c5c-538b-41f3-9aaa-c2a282b43b6f).html; https://doi.org/10.2216/05-03.1

The potential to acclimate photosynthesis to sub- and supra-optimal temperatures was investigated in seven isolates of Valonia utricularis (Roth) C. Agardh, a green macrophyte with a tropical to warm-temperate distribution. Photosynthesis-light response curves were obtained by measuring chlorophyll a fluorescence characteristics of algae grown at optimal (25 degrees C), sub- and supra-optimal temperatures. Suboptimal temperatures were chosen to support 30% of the maximum relative growth rate in each isolate. Thermal acclimation was investigated by comparing short-term and long-term temperature effects on the initial rate of increase of the relative electron transport rate (rETR) and the maximum rETR under light-saturating conditions. Isolates from the northeast Atlantic and the Mediterranean all showed a strong potential to acclimate maximum rETR to suboptimal growth temperatures, i.e. short-term temperature effects were diminished after acclimation. However, photoinhibition, measured as a decrease of the maximal quantum yield (F(v)/F(m)), was found when plants were grown at 30 degrees C. The isolates reduced light harvesting at 30 degrees C by decreasing total chlorophyll content and by increasing the chlorophyll a/b ratio. Up-regulation of photoprotective processes by the xanthophyll cycle pigments was not observed. In contrast, isolates from the Indo-west Pacific were unable to acclimate photosynthesis to suboptimal growth temperatures and these temperatures were strongly photoinhibiting, even though adjustments on the pigment level were observed. All Indo-west Pacific isolates reached comparable maximum rETR values at 30 and 25 degrees C. Thus, the Atlantic/Mediterranean isolates had a stronger potential to acclimate photosynthetic rates at suboptimal growth temperatures compared to the Indo-west Pacific isolates, which was accompanied by losses at 30 degrees C. The results are discussed in a biogeographical context.