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A common partitioning strategy for photosynthetic products in evolutionarily distinct phytoplankton species
Author(s) -
Halsey Kimberly H.,
O'Malley Robert T.,
Graff Jason R.,
Milligan Allen J.,
Behrenfeld Michael J.
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12209
Subject(s) - photosynthesis , carbon fixation , thalassiosira weissflogii , phytoplankton , biology , diatom , nutrient , carbon fibers , thalassiosira pseudonana , botany , algae , growth rate , ecology , materials science , geometry , mathematics , composite number , composite material
Summary We compare the nutrient‐dependent photosynthetic efficiencies of the chlorophyte, Dunaliella tertiolecta , with those of the marine diatom, Thalassiosira weissflogii . Despite considerable evolutionary and physiological differences, these two species appear to use nearly identical growth strategies under a wide range of nutrient limitation. Using a variety of physiological measurements, we find that, for both species and across all growth rates, 75% of the gross photosynthetic electron flow is invested in carbon fixation and only 30% is retained as net carbon accumulation. A majority of gross photosynthesis (70%) is ultimately used as reductant for biosynthetic pathways and for the generation of ATP . In both species, newly formed carbon products exhibit much shorter half‐lives at slow growth rates than at fast growth rates. We show that this growth rate dependence is a result of increased polysaccharide storage during the S phase of the cell cycle. We present a model of carbon utilization that incorporates this growth rate‐dependent carbon allocation and accurately captures ( r 2 = 0.94) the observed time‐resolved carbon retention. Together, our findings suggest a common photosynthetic optimization strategy in evolutionarily distinct phytoplankton species and contribute towards a systems‐level understanding of carbon flow in photoautotrophs.