Fluorescence as a Tool to Understand Changes in Photosynthetic Electron Flow Regulation
Résumé
The physiological state of a chloroplast is strongly
influenced by both biotic and abiotic conditions.
Unfavourable growth conditions lead to photosynthetic
stress. Chlorophyll a fluorescence is a widely
used probe of photosynthetic activity (specifically
PSII), and therefore stress which specifically targets
the electron transport pathway and associated alternative
electron cycling pathways. By manipulating the
processes that control photosynthesis, affecting the
chlorophyll a fluorescence, yields detailed insight into
the biochemical
pathways. Light that is captured by a
chlorophyll molecule can be utilised in three competing
processes; electron transport, energy dissipation
(via heat) and chlorophyll a fluorescence emission.
Electrons produced by water-splitting are not always
used in carbon fixation; if the incident irradiance
generates
more electrons than the dark reactions
can use in carbon fixation, damage will occur to the photosynthetic apparatus. If carbon fixation is inhibited
by temperature or reduced inorganic carbon (Ci), ATP
or NADPH availability, then the photosystem dynamically
adjusts and uses alternate sinks for electrons, such
as molecular oxygen (water-water cycle or Mehler ascorbate
peroxidase reaction). The process of stress acclimation
leads to a number of photoprotective pathways
and we describe how inhibitors can be used to identify
these particular processes. In this chapter, we describe
the processes controlling electron transport as influenced
by light-induced stress.
Origine : Fichiers produits par l'(les) auteur(s)
Loading...