• Home
  • Search Results
  • Tobacco guard cells fix CO2 by both Rubisco and PEPcase while sucrose acts as a substrate during light-induced stomatal opening.

Tobacco guard cells fix CO2 by both Rubisco and PEPcase while sucrose acts as a substrate during light-induced stomatal opening.

Plant, cell & environment (2015-04-15)
Danilo M Daloso, Werner C Antunes, Daniela P Pinheiro, Jardel P Waquim, Wagner L Araújo, Marcelo E Loureiro, Alisdair R Fernie, Thomas C R Williams
ABSTRACT

Transcriptomic and proteomic studies have improved our knowledge of guard cell function; however, metabolic changes in guard cells remain relatively poorly understood. Here we analysed metabolic changes in guard cell-enriched epidermal fragments from tobacco during light-induced stomatal opening. Increases in sucrose, glucose and fructose were observed during light-induced stomatal opening in the presence of sucrose in the medium while no changes in starch were observed, suggesting that the elevated fructose and glucose levels were a consequence of sucrose rather than starch breakdown. Conversely, reduction in sucrose was observed during light- plus potassium-induced stomatal opening. Concomitant with the decrease in sucrose, we observed an increase in the level as well as in the (13) C enrichment in metabolites of, or associated with, the tricarboxylic acid cycle following incubation of the guard cell-enriched preparations in (13) C-labelled bicarbonate. Collectively, the results obtained support the hypothesis that sucrose is catabolized within guard cells in order to provide carbon skeletons for organic acid production. Furthermore, they provide a qualitative demonstration that CO2 fixation occurs both via ribulose-1,5-biphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPcase). The combined data are discussed with respect to current models of guard cell metabolism and function.

MATERIALS
Product Number
Brand
Product Description

Supelco
MSTFA Reagent, ampule of 10 × 1.2 mL, analytical standard, Cerilliant®
Sigma-Aldrich
Sodium hydroxide, ultra dry, powder or crystals, 99.99% trace metals basis
Sigma-Aldrich
D-Mannitol, BioXtra, ≥98% (HPLC)
Sigma-Aldrich
D-Mannitol, ACS reagent
Sigma-Aldrich
D-Mannitol, meets EP, FCC, USP testing specifications
Sigma-Aldrich
D-Mannitol, ≥98%
Sigma-Aldrich
D-Mannitol, suitable for plant cell culture
Sigma-Aldrich
Chloroform, ≥99%, PCR Reagent, contains amylenes as stabilizer
Sigma-Aldrich
Sodium hydroxide solution, 1.0 N, BioReagent, suitable for cell culture
Supelco
N-Methyl-bis(trifluoroacetamide), for GC derivatization, LiChropur, ≥97.0% (GC)
Supelco
Pyridine solution, certified reference material, 2000 μg/mL in methanol
Sigma-Aldrich
Chloroform, anhydrous, ≥99%, contains 0.5-1.0% ethanol as stabilizer
Supelco
Chloroform, analytical standard
Supelco
Chloroform, suitable for HPLC, ≥99.8%
Sigma-Aldrich
Chloroform, ACS reagent, ≥99.8%, contains amylenes as stabilizer
Sigma-Aldrich
Chloroform, ACS reagent, ≥99.8%, contains 0.5-1.0% ethanol as stabilizer
Sigma-Aldrich
3-Ethyl-2,4-pentanedione, mixture of tautomers, 98%
Sigma-Aldrich
Methoxylamine hydrochloride solution, 25-30 wt. % in H2O
Sigma-Aldrich
Sodium hydroxide, BioUltra, for luminescence, ≥98.0% (T), pellets
Sigma-Aldrich
Sodium hydroxide solution, BioUltra, for molecular biology, 10 M in H2O
Sigma-Aldrich
D-Mannitol, BioUltra, ≥99.0% (sum of enantiomers, HPLC)
Supelco
Chloroform, suitable for HPLC, ≥99.8%, contains 0.5-1.0% ethanol as stabilizer
Sigma-Aldrich
Chloroform, anhydrous, contains amylenes as stabilizer, ≥99%
Sigma-Aldrich
Methoxyamine hydrochloride, 98%
Sigma-Aldrich
Sodium hydroxide, anhydrous, free-flowing, Redi-Dri, reagent grade, ≥98%, pellets
Sigma-Aldrich
Sodium hydroxide, reagent grade, 97%, flakes
Sigma-Aldrich
Chloroform, biotech. grade, ≥99.8%, contains 0.5-1.0% ethanol as stabilizer
Sigma-Aldrich
Chloroform, contains ethanol as stabilizer, meets analytical specification of BP, 99-99.4% (GC)
Sigma-Aldrich
Sodium hydroxide, pellets, semiconductor grade, 99.99% trace metals basis
Sigma-Aldrich
Sodium hydroxide, beads, 20-40 mesh, reagent grade, 97%