Effect of iron limitation on photosynthesis in a marine diatom

Journal Article · Sun Dec 01 00:00:00 EST 1991 · Limnology and Oceanography; (United States)

DOI:https://doi.org/10.4319/lo.1991.36.8.1772· OSTI ID:7111732

Greene, R M; Falkowski, P G ^[1]; Geider, R J ^[2]

---

1. Brookhaven National Lab., Upton, NY (United States)
2. Univ. of Delaware, Lewes (United States)

The response of the marine diatom Phaeodactylum tricornutum to Fe deficiency was evaluated in the context of fundamental physiological models of growth and photosynthesis. Fe deficiency induced chlorosis, which decreased Chl a:C ratios and Chl a-specific light-saturated photosynthesis (P{sub m}{sup B}). In contrast to P{sub m}{sup B}, {alpha}{sup B} was slightly increased under Fe deficiency, and photosynthesis in Fe-deficient cells became light-saturated at lower irradiances than in Fe-replete cells grown at the same irradiance. Fe deficiency increased in vivo absorption cross section normalized to Chl a(a{sup *}), but decreased the maximum quantum yield of photosynthesis ({phi}{sub m}). Thus, the product a{sup *} {phi}{sub m}, which equals the Chl a-specific initial slope of the photosynthesis-irradiance curve ({alpha}{sup B}), was less sensitive to Fe limitation than was a{sup *} or {phi}{sub m} alone. Using a pump-and-probe fluorometer, the authors found that Fe deficiency reduced the maximum fluorescence yield ({Delta}{phi}{sub sat}), which is consistent with the reduction in {phi}{sub m}, but increased the absorption cross section of photosystem 2 ({sigma}{sub PS2}). Immunoassays of proteins separated electrophoretically indicated that the reduction in maximum fluorescence yields as accompanied by a reduction in the relative abundance of D1, the photosystem 2 reaction center protein. Light-harvesting chlorophyll proteins (LHCP) and the large and small subunits of ribulose bisphosphate carboxylase were not affected by Fe deficiency. Changes in the abundance of D1 relative to LHCP suggest an increase in the fraction of nonfunctional reaction centers under Fe-limited conditions. Fe-deficient cells, growing at <20% of their maximum growth rate, and reduced cellular C, N, and P contents, but maintained C:N:P ratios at the Redfield proportions. These results imply that C:N:P ratios do not provide and unequivocal index of relative growth rate.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 7111732
• Journal Information: Limnology and Oceanography; (United States), Vol. 36:8, Issue 8; ISSN 0024-3590
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
29 ENERGY PLANNING
POLICY AND ECONOMY
DIATOMS
PHOTOSYNTHESIS
IRON
BIOLOGICAL AVAILABILITY
CARBON SINKS
CHLOROPHYLL
ELECTROPHORESIS
FLUORESCENCE
GROWTH
IMMUNOASSAY
NUTRIENTS
PHOTOSYNTHETIC REACTION CENTERS
RIBULOSE DIPHOSPHATE CARBOXYLASE
ALGAE
BIOASSAY
CARBON-CARBON LYASES
CARBOXY-LYASES
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHROMOPHYCOTA
ELEMENTS
ENZYMES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
LUMINESCENCE
LYASES
METALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHYTOCHROMES
PIGMENTS
PLANTS
PORPHYRINS
PROTEINS
SINKS
SYNTHESIS
TRANSITION ELEMENTS
540320* - Environment
Aquatic- Chemicals Monitoring &amp; Transport- (1990-)
560300 - Chemicals Metabolism &amp; Toxicology
290301 - Energy Planning &amp; Policy- Environment
Health
&amp; Safety- Regional &amp; Global Environmental Aspects- (1992-)