Betaine synthesis from radioactive precursors in attached, water-stressed barley leaves

Journal Article · Fri Aug 01 04:00:00 EDT 1980 · Plant Physiol.; (United States)

DOI:https://doi.org/10.1104/pp.66.2.342· OSTI ID:6773484

Hanson, A D; Scott, N A

In wilted barley leaves, betaine accumulates at about 200 nanomoles per 10 centimeters leaf per day. Results with /sup 14/C-labeled precursors were qualitatively and quantitatively consistent with de novo synthesis of this betaine from serine via ethanolamine, choline, and betaine aldehyde and indicated that water stress may increase the activities of all steps in this pathway except the last. Doses (I micromole) of each /sup 14/C-labeled precursor were supplied as droplets to the tips of attached, 10-centimeter, second-leaf blades of turgid and wilted plants, and the incorporation of /sup 14/C into betaine was followed. From the rates of betaine labeling, estimates were made of the potential capacities (nanomoles per 10 centimeters leaf per day) for the methylation and oxidation steps. Labeling of betaine from absolute value /sup 14/C choline, absolute value /sup 14/C ethanolamine, and absolute value /sup 14/C serine was about 7- to 10-fold greater in leaves wilted for 2 days than in turgid leaves, whereas label from absolute value /sup 14/C betaine aldehyde appeared in betaine at about the same rate in both turgid and wilted leaves. In leaves wilted for 2 days, the potential capacities for converting absolute value /sup 14/C ethanolamine, absolute value /sup 14/C choline, and absolute value /sup 14/C betaine aldehyde to betaine all approached or exceeded the rate of betain accumulation (about 200 nanomoles per 10 centimeters leaf per day); in turgid leaves, only the potential for converting betaine aldehyde to betaine exceeded this rate. The rate of conversion of absolute value /sup 14/C ethanolamine to betaine increased 4-fold after 6 to 10 hours of wilting, which was soon enough to account for the onset of betaine accumulation.

• Research Organization: Michigan State Univ., East Lansing
• DOE Contract Number: AC02-76ER01338
• OSTI ID: 6773484
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 66:2; ISSN PLPHA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
ALCOHOLS
ALDEHYDES
AMINES
AMINO ACIDS
AMMONIUM COMPOUNDS
BARLEY
BETAINE
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL ACCUMULATION
BIOLOGICAL ADAPTATION
BIOLOGICAL STRESS
BIOLOGY
BIOSYNTHESIS
BOTANY
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
CEREALS
CHEMICAL ANALYSIS
CHOLINE
DRUGS
GRAMINEAE
GRASS
HYDROGEN COMPOUNDS
HYDROXY ACIDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LEAVES
LIPOTROPIC FACTORS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PLANTS
QUANTITATIVE CHEMICAL ANALYSIS
QUATERNARY COMPOUNDS
RADIOCHEMICAL ANALYSIS
REACTION KINETICS
SALINITY
SENSITIVITY
SERINE
SYNTHESIS
TRACER TECHNIQUES
WATER