Regulation of photosynthetic pigments in micro-algae by multiple environmental factors: a dynamic balance hypothesis

Authors


To whom correspondence should be addressed. E-mail: kana@hpl.umces.edu

summary

Environmental effects on the concentration of photosynthetic pigments in micro-algae can be explained by dynamics of photosystem synthesis and deactivation. A model that couples photosystem losses to the relative cellular rates of energy harvesting (light absorption) and assimilation predicts optimal concentrations of light-harvesting pigments and balanced energy flow under environmental conditions that affect light availability and metabolic rates. Effects of light intensity, nutrient supply and temperature on growth rate and pigment levels were similar to general patterns observed across diverse micro-algal taxa. Results imply that dynamic behaviour associated with photophysical stress, and independent of gene regulation, might constitute one mechanism for photo-acclimation of photosynthesis.

Unusual Abbreviation
A

rate of photosynthetic assimilation per unit cell

Amax

maximum rate of assimilation determined by rate of cell metabolism

chl

chlorophyll

D1

psbA gene product

g

generation time (h)

1

irradiance

LHC II

light-harvesting chlorophyll protein II and cab gene product

n

number of photosystems

PQ

plastoquinone

PQH2

reduced PQ

PS II

photosystem II

PSU

photosynthetic light-harvesting unit

Qcell

cellular quota of reductant required for cell division

Q10

factor relating the relative rate of reaction over a 10 °C interval

μ

specific growth rate (units as h−1)

μmax

maximum growth rate

σ

optical absorption cross-section of PS II

Ancillary