Premium
The nitrogen costs of photosynthesis in a diatom under current and future p CO 2
Author(s) -
Li Gang,
Brown Christopher M.,
Jeans Jennifer A.,
Donaher Natalie A.,
McCarthy Avery,
Campbell Douglas A.
Publication year - 2015
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.13037
Subject(s) - photosynthesis , photoinhibition , photosystem ii , carbon fixation , biology , photorespiration , botany , light intensity , thalassiosira pseudonana , diatom , biophysics , photosynthetic reaction centre , nutrient , ecology , phytoplankton , physics , optics
Summary With each cellular generation, oxygenic photoautotrophs must accumulate abundant protein complexes that mediate light capture, photosynthetic electron transport and carbon fixation. In addition to this net synthesis, oxygenic photoautotrophs must counter the light‐dependent photoinactivation of Photosystem II ( PSII ), using metabolically expensive proteolysis, disassembly, resynthesis and re‐assembly of protein subunits. We used growth rates, elemental analyses and protein quantitations to estimate the nitrogen ( N ) metabolism costs to both accumulate the photosynthetic system and to maintain PSII function in the diatom T halassiosira pseudonana, growing at two p CO 2 levels across a range of light levels. The photosynthetic system contains c . 15–25% of total cellular N . Under low growth light, N (re)cycling through PSII repair is only c . 1% of the cellular N assimilation rate. As growth light increases to inhibitory levels, N metabolite cycling through PSII repair increases to c . 14% of the cellular N assimilation rate. Cells growing under the assumed future 750 ppmv p CO 2 show higher growth rates under optimal light, coinciding with a lowered N metabolic cost to maintain photosynthesis, but then suffer greater photoinhibition of growth under excess light, coincident with rising costs to maintain photosynthesis. We predict this quantitative trait response to light will vary across taxa.