Radiotracer evidence implicating phosphoryl and phosphatidyl bases as intermediates in betaine synthesis by water-stressed barley leaves

Journal Article · Thu Oct 01 04:00:00 EDT 1981 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.68.4.814· OSTI ID:5763130

Hitz, W D; Rhodes, D; Hanson, A

In pulse-chase experiments with barley wilted leaves, label from (/sup 14/C)-ethanolamine continued to accumulate in betaine as it was being lost from phosphatidylcholine. When (/sup 14/C)monomethylethanolamine was supplied to wilted leaves, phosphatidylcholine was initially more heavily labeled than betaine. These results are qualitatively consistent with a precursor-to-product relationship between phosphatidylcholine and betaine. The following experiments, in which tracer amounts of (/sup 14/C)ethanolamine or (/sup 14/C)formate were supplied to wilted barley leaves, implicated phosphoryl and phosphatidyl bases as intermediates in the methylation steps between ethanolamine and phosphatidylcholine. Label from both (/sup 14/C)ethanolamine and (/sup 14/C)formate entered phosphorylmonomethylethanolamine and phosphorylcholine very rapidly; these phosphoryl bases were the most heavily labeled products at 15 to 30 minutes after label addition and lost label rapidly as the fed /sup 14/C-labeled precursor was depleted. Phosphatidylmonomethylethanolamine and phosphatidylcholine were also significantly labeled from (/sup 14/C)ethanolamine and (/sup 14/)formate at early times; the corresponding free bases and nucleotide bases were not. Addition of a trapping pool of phosphorylcholine reduced (/sup 14/C)ethanolamine conversion to both phosphatidylcholine and betaine, and resulted in accumulation of labe in the trap. A computer model of the synthesis of betaine via phosphatidylcholine was developed from /sup 14/C kinetic data. The model indicates that about 20% of the total leaf phosphatidylcholine behaves as an intermediate in betaine biosynthesis and that a marked decrease (greater than or equal to2-fold) in the half-life of this metabolically active phosphatidylcholine fraction accompanies wilting.

• Research Organization: Michigan State Univ., East Lansing
• DOE Contract Number: AC02-76ER01338
• OSTI ID: 5763130
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 68:4; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINES
AMINO ACIDS
AMMONIUM COMPOUNDS
AUTORADIOGRAPHY
BARLEY
BETAINE
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL PATHWAYS
BIOLOGICAL STRESS
BIOSYNTHESIS
CARBON COMPOUNDS
CARBOXYLIC ACIDS
CEREALS
CHEMICAL REACTIONS
CHROMATOGRAPHY
COMPUTERIZED SIMULATION
DATA
DRUGS
ESTERS
EVALUATED DATA
EXPERIMENTAL DATA
GRAMINEAE
GRASS
INFORMATION
ISOMERIC NUCLEI
ISOTOPE APPLICATIONS
KINETICS
LEAVES
LIPIDS
LIPOTROPIC FACTORS
METABOLISM
METHYLATION
NUCLEI
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHOLIPIDS
PLANTS
QUATERNARY COMPOUNDS
REACTION KINETICS
REMOVAL
SEPARATION PROCESSES
SIMULATION
SYNTHESIS
THIN-LAYER CHROMATOGRAPHY
TRACER TECHNIQUES
WATER REMOVAL