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- Title
ALGAL PHOTOSYNTHETIC MEMBRANE COMPLEXES AND THE PHOTOSYNTHESIS-IRRADIANCE CURVE: A COMPARISON OF LIGHT-ADAPTATION RESPONSE IN <em>CHLAMYDOMONAS REINHARDTII</em> (CHLOROPHYTA).
- Authors
Neale, Patrick J.; Melis, Anastasois
- Abstract
Chalmydomonas reinhardtii was grown at photon flux densities (PFDs) ranging from 47 to 400 μE·m[sup-2]·s[sup-1]. The total cellular content of chlorophyll (Chl) was twice as high in the low light (HL) grown cells. On an equal Chl basis, photosystem II (PSII) ans cytochrome f (Cyt f) cntent was higher in HL cells, nut photosystem I (PSI) concenquently, there was a shift in the ratio of PSII/PSI and Cyt f/PSI from near unity un LL cells to greater than two in HL cells. The functional Chl antenna size of PSII and PSI ranged from 460 and 170 Chl (a + b) om JL-grown cells to 620 and -370 Chl (a + b) in LL-grown cells, respectively. The initial slope of the Chl-specific photosynthesis-irradiance (P-I) curve was similar in LL- and HL-grown cells, but the light saturated rate of photosynthesis was lower under LL. The response to low light was beneficial at the cellular level, since there was an enhancement of photosynthesis in LL. The PFD for the onset of light saturation, I was a factor of ten, photosynthesis shifted from being light-limited in the LL regime to light-saturated in the HL regime. The requirement for balanced absorption of light by the two photosystems constrains the PSII/PSI ratio to near unity when growth is light-limited, but such a constraint does not apply in HL conditions. Instead the concentration of individual electron transport complexes may be related to the pool size necessary for maximum rates of steady-state electron transport. Thus the stoichiometry of electron transport complexes changes in response to growgth PFD and this change is correlated with the response flexibility o falgal photosynthesis in diverse light environments.
- Subjects
PHOTOSYNTHESIS; GREEN algae; PHOTOSYNTHETIC reaction centers; CHLOROPHYLL; STOICHIOMETRY; ELECTRON transport
- Publication
Journal of Phycology, 1986, Vol 22, Issue 4, p531
- ISSN
0022-3646
- Publication type
Article
- DOI
10.1111/j.1529-8817.1986.tb02497.x