ADAPTATION OF PHOTOSYNTHESIS IN LAMINARIA SACCHARINA (PHAEOPHYTA) TO CHANGES IN GROWTH TEMPERATURE¹

Abstract

The effect of growth temperature on photosynthetic metabolism was studied in the kelp Laminaria saccharina (L.) Lamour. Photosynthesis was subject to phenotypic adaptation, with almost constant photosynthetic rates being achieved at growth temperatures between 0 and 20° C. This response involved: (1) an inverse relationship between growth temperature and photosynthetic capacity, (2) a reduction in the Q10 value for photosynthesis of L. saccharina grown at 0 and 5° C compared with 10, 15 and 20° C grown sporophytes, and (3) an acquired tolerance of photosynthesis to temperatures between 15–25° C (which inhibited photosynthesis in 0 and 5° C grown L. saccharina) in sporophytes grown at 10, 15 and 20° C. The physiological basis of these adaptations is discussed in terms of observed changes in activities and kinetics of the Calvin cycle enzyme ribulose‐1, 5‐bisphosphate carboxylase (oxygenase) and efficiency of light harvesting‐electron transport systems.

Thermal acclimation of light-use characteristics ofChondrus crispus(Rhodophyta)

“…1B). These differences are typical of those previously reported for macroalgae and microalgae grown at different constant temperatures (Davison, 1987(Davison, , 1991Geider, 1987;Raven & Geider, 1988). In contrast, the green macroalga, Ulva rotundata Bliding, showed little scope for acclimation to growth temperature though there was significant interaction between the effects of growth temperature and growth light level on the photosynthetic characteristics in that species (Henley, 1992).…”

“…In Chondrus crispus, in contrast to many plants (Davison, 1987), acclimation did not affect rates of light-saturated photosynthesis (Fig. 1A), but involved changes in light-limited photosynthesis (Fig.…”

Inadequacy of Rubisco initial and total activities to account for observed rates of photosynthetic carbon dioxide assimilation byScenedesmus ecornis

“…Thus, changes in specific activity could lead to decreases in the carbon assimilated during the enzyme assay. On the other hand, Rubisco activities consistent with the corresponding photosynthetic rates (Aizawa et al, 1985;Yokota & Canvin, 1986;Elrifi et al, 1988), and even higher (Davison, 1987), have been obtained. However, these activities were always based on the CO2-Mg2+-activated form of the enzyme.…”

Photosynthetic response of Arctic kelp zoospores exposed to radiation and thermal stress

“…58 The temperature optima for photosynthesis in different kelp species' zoospores were observed between 7 • C and 13 • C higher than that of the reported optimum temperature for germination between 2 • C and 12 • C. 33 The same discrepancy between the thermal relationships of growth and photosynthesis in S. latissima sporophytes was observed and discussed by Davison. 23, 42 The thermal stability of PSII effectively determines the upper temperature tolerance of photosynthesis. Above the temperature optima, the lability of PSII is dependent on the period of heat stress.…”