Photosynthesis Research

, Volume 112, Issue 3, pp 175–191

Photosynthetic responses of a C3 and three C4 species of the genus Panicum (s.l.) with different metabolic subtypes to drought stress

Regular Paper

DOI: 10.1007/s11120-012-9763-4

Cite this article as:
Alfonso, S.U. & Brüggemann, W. Photosynth Res (2012) 112: 175. doi:10.1007/s11120-012-9763-4

Abstract

Young plants of Panicum bisulcatum (C3), Zuloagaea bulbosa [NADP-malic enzyme (ME)-C4], P. miliaceum (NAD-ME-C4) and Urochloa maxima [phosphoenolpyruvate carboxykinase (PCK)-C4] were subjected to drought stress (DS) in soil for 6 days. The C3 species showed severe wilting symptoms at higher soil water potential (−1.1 MPa) and relative leaf water content (77 %) than in the case of the C4 species (−1.5 to −1.7 MPa; 58–64 %). DS decreased photosynthesis, both under atmospheric and under saturating CO2. Stomatal limitation of net photosynthesis (PN) in the C3, but not in the C4 species was indicated by PN/Co curves. Chlorophyll fluorescence of photosystem II, resulting from different cell types in the four species, indicated NADPH accumulation and non-stomatal limitation of photosynthesis in all four species, even under high CO2. In the NAD-ME-C4 and the PCK-C4 species, DS plants showed increased violaxanthin de-epoxidase rates. Biochemical analyses of carboxylating enzymes and in vitro enzyme activities of the C4 enzymes identified the most likely non-stomatal limiting steps of photosynthesis. In P. bisulcatum, declining RubisCO content and activity would explain the findings. In Z. bulbosa, all photosynthesis enzymes declined significantly; photosynthesis is probably limited by the turnover rate of the PEPC reaction. In P. miliaceum, all enzyme levels remained fairly constant under DS, but photosynthesis can be limited by feedback inhibition of the Calvin cycle, resulting in asp inhibition of PEPC. In U. maxima, declines of in vivo PEPC activity and feedback inhibition of the Calvin cycle are the main candidates for non-stomatal limitation of photosynthesis under DS.

Keywords

Drought stress Photosynthesis Chlorophyll fluorescence C4 plants Panicum NADP-ME NAD-ME PCK 

Abbreviations

A

Antheraxanthin

Ala

Alanine

Asp

Aspartate

AT

Amino transferase

BSC

Bundle sheath cells

C

Control

Ci

Intercellular CO2

Chl

Chlorophyll

Co

Ambient (applied) CO2

Cyt

Cytosolic

DES

De-epoxidation state

DS

Drought stress(ed)

DTT

Dithiothreitol

EB

Extraction buffer

ETR

Electron transport rate

ΦPSII

Quantum yield of PS II in the light-adapted state

gs

Stomatal conductance

IC50

50 % inhibiting concentration

LSU

Large subunit

MC

Mesophyll cells

MDH

malate dehydrogenase

ME

Malic enzyme

mt

Mitochondrial

NAD-ME

NAD-malic enzyme

NADP-ME

NADP-malic enzyme

NPQ

Non-photochemical quenching

PBS

Phosphate buffered saline

PCK

Phosphoenolpyruvate carboxykinase

PN

Net photosynthesis

PEP

Phosphoenolpyruvate

PEPC

PEP carboxylase

PPDK

Pyruvate, orthophosphate dikinase

PS II

Photosystem II

qE

Energy-dependent quenching

qI

Photoinhibitory quenching

qP

Photochemical quenching

RubisCO

Ribulose-1,5-bisphosphate carboxylase/oxygenase

SSU

Small subunit

SWC

Soil water content

T

Transpiration rate

V

Violaxanthin

VD

Violaxanthin de-epoxidase

WUE

Water use efficiency

Z

Zeaxanthin

Supplementary material

11120_2012_9763_MOESM1_ESM.pdf (170 kb)
Supplementary material 1 (PDF 170 kb)
11120_2012_9763_MOESM2_ESM.tif (365 kb)
Supplementary material 2 (TIFF 364 kb)
11120_2012_9763_MOESM3_ESM.pdf (45 kb)
Supplementary material 3 (PDF 45 kb)
11120_2012_9763_MOESM4_ESM.pdf (42 kb)
Supplementary material 4 (PDF 41 kb)

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  1. 1.Department of Ecology, Evolution and DiversityUniversity of FrankfurtFrankfurtGermany
  2. 2.Biodiversity and Climate Research CentreFrankfurtGermany

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