In search of a physiological basis for covariations in light-limited and light-saturated photosynthesis - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Phycology Année : 2004

In search of a physiological basis for covariations in light-limited and light-saturated photosynthesis

Mj Behrenfeld
  • Fonction : Auteur
O Prasil
  • Fonction : Auteur
F Bruyant
  • Fonction : Auteur

Résumé

The photosynthesis-irradiance (PE) relationship links indices of phytoplankton biomass (e.g. chl) to rates of primary production. The PE curve can be characterized by two variables: the light-limited slope (alpha(b)) and the light-saturated rate (P-max(b)) of photosynthesis. Variability in PE curves can be separated into two categories: that associated with changes in the light saturation index, E-k (=P-max(b)/alpha(b)) and that associated with parallel changes in alpha(b)and P-max(b) (i.e. no change in E-k). The former group we refer to as ``E-k-dependent'' variability, and it results predominantly from photoacclimation (i.e. physiological adjustments in response to changing light). The latter group we refer to as ``E-k-independent'' variability, and its physiological basis is unknown. Here, we provide the first review of the sporadic field and laboratory reports of E-k-independent variability, and then from a stepwise analysis of potential mechanisms we propose that this important yet largely neglected phenomenon results from growth rate-dependent variability in the metabolic processing of photosynthetically generated reductants (and generally not from changes in the oxygen-evolving PSII complexes). Specifically, we suggest that as growth rates decrease (e.g. due to nutrient stress), reductants are increasingly used for simple ATP generation through a fast (<1s) respiratory pathway that skips the carbon reduction cycle altogether and is undetected by standard PE methodologies. The proposed mechanism is consistent with the field and laboratory data and involves a simple new ``twist'' on established metabolic pathways. Our conclusions emphasize that simple reductants, not reduced carbon compounds, are the central currency of photoautotrophs.

Domaines

Océanographie

Dates et versions

hal-03506683 , version 1 (02-01-2022)

Identifiants

Citer

Mj Behrenfeld, O Prasil, M Babin, F Bruyant. In search of a physiological basis for covariations in light-limited and light-saturated photosynthesis. Journal of Phycology, 2004, 40 (1), pp.4-25. ⟨10.1046/j.1529-8817.2004.03083.x⟩. ⟨hal-03506683⟩
20 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More