Photosynthesis Research

, Volume 121, Issue 2, pp 285–297

Biochemical and biophysical CO2 concentrating mechanisms in two species of freshwater macrophyte within the genus Ottelia (Hydrocharitaceae)

Regular Paper

DOI: 10.1007/s11120-013-9950-y

Cite this article as:
Zhang, Y., Yin, L., Jiang, HS. et al. Photosynth Res (2014) 121: 285. doi:10.1007/s11120-013-9950-y

Abstract

Two freshwater macrophytes, Ottelia alismoides and O. acuminata, were grown at low (mean 5 μmol L−1) and high (mean 400 μmol L−1) CO2 concentrations under natural conditions. The ratio of PEPC to RuBisCO activity was 1.8 in O. acuminata in both treatments. In O. alismoides, this ratio was 2.8 and 5.9 when grown at high and low CO2, respectively, as a result of a twofold increase in PEPC activity. The activity of PPDK was similar to, and changed with, PEPC (1.9-fold change). The activity of the decarboxylating NADP-malic enzyme (ME) was very low in both species, while NAD-ME activity was high and increased with PEPC activity in O. alismoides. These results suggest that O. alismoides might perform a type of C4 metabolism with NAD-ME decarboxylation, despite lacking Kranz anatomy. The C4-activity was still present at high CO2 suggesting that it could be constitutive. O. alismoides at low CO2 showed diel acidity variation of up to 34 μequiv g−1 FW indicating that it may also operate a form of crassulacean acid metabolism (CAM). pH-drift experiments showed that both species were able to use bicarbonate. In O. acuminata, the kinetics of carbon uptake were altered by CO2 growth conditions, unlike in O. alismoides. Thus, the two species appear to regulate their carbon concentrating mechanisms differently in response to changing CO2. O. alismoides is potentially using three different concentrating mechanisms. The Hydrocharitaceae have many species with evidence for C4, CAM or some other metabolism involving organic acids, and are worthy of further study.

Keywords

Bicarbonate use CAM C4 metabolism Organic acids Photosynthesis 

Abbreviations

AMP

Adenosine monophosphate

ATP

Adenosine triphosphate

Alk

Alkalinity

CAM

Crassulacean acid metabolism

CCM

Carbon dioxide concentrating mechanism

DIC

Dissolved inorganic carbon

DTT

Dithiothreitol

FW

Fresh weight

GAPDH

Glyceraldehyde 3-phosphate dehydrogenase

LDH

Lactate dehydrogenase

MDH

Malate dehydrogenase

NAD(P)-ME

NAD(P)-malic enzyme

OAA

Oxaloacetate

PEP

Phosphoenol pyruvate

PEPC

PEP carboxylase

PEPCK

PEP carboxykinase

PGK

Phosphoglycerate kinase

PPDK

Pyruvate phosphate dikinase

RuBisCO

Ribulose 1,5-bisphosphate carboxylase–oxygenase

RuBP

Ribulose 1,5-bisphosphate

Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical GardenChinese Academy of SciencesWuhanChina
  2. 2.University of Chinese Academy of SciencesBeijingChina
  3. 3.Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical GardenChinese Academy of SciencesWuhanChina
  4. 4.UMR 7281, BIP, CNRSAix Marseille Université-CNRSMarseille Cedex 20France
  5. 5.Lake Ecosystems Group, Centre for Ecology & HydrologyLancaster Environment CentreLancasterUK

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