Betaine synthesis and accumulation in barley during field water-stress

Journal Article · Fri Jan 01 00:00:00 EST 1982 · Crop Sci.; (United States)

DOI:https://doi.org/10.2135/cropsci1982.0011183X002200010011x· OSTI ID:6173311

Hitz, W D; Ladyman, J A.R.; Hanson, A D

The timing and extent of betaine accumulation by mature leaves of barley (Hordeum vulgare L.) were followed in irrigated (I) and non-irrigated (N-I) plots under rain-shelters. In the N-I crop, leaf water potential (/sup psi/leaf) began to fall at the five-leaf stage, continued to drop steadily until maturity, and reached a minimum of about -35 bars. Betaine accumulation started in the N-I crop about a week after the decline in /sup psi/leaf began and continued until about 10 days post-anthesis. The maximum betaine concentration attained by N-I leaves (100 ..mu..mol/g dry wt) was three times that in I leaves. Betaine accumulation by upper leaves was due mainly to de novo synthesis in these leaves, because: (1) there was little /sup 14/C-import into upper leaves when (/sup 14/C)betaine was applied to lower leaves, and (2) attached upper leaves of N-I plants rapidly converted supplied (/sup 14/C)ethanolamine to (/sup 14/C)betaine during the peak period of betaine accumulation. Phosphatidylcholine (PC) behaved as an intermediate in the conversion of (/sup 14/C)ethanolamine to betaine. The estimated peak metabolic cost of betaine biosynthesis via PC by stressed leaves (about 2 mg hexose/g dry wt/day) approached the cost of protein turnover in the same leaves (3 to 5 mg hexose/g dry wt/day) as estimated from (/sup 3/H) lysine incorporation. In N-I plants, cessation of betaine synthesis preceded the onset of senescence by several days, indicating that continuous betaine production is not mandatory for leaf function at lowered /sup psi/leaf. These field results are consistent with an adaptive value for betaine accumulation in barley during prolonged water stress. A search for genetic variation in betaine-accumulating potential in barley is now warranted.

• Research Organization: Michigan State Univ., East Lansing
• DOE Contract Number: AC02-76ER01338
• OSTI ID: 6173311
• Journal Information: Crop Sci.; (United States), Vol. 22:1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
BARLEY
BIOLOGICAL STRESS
BETAINE
BIOLOGICAL ACCUMULATION
BIOSYNTHESIS
BIOLOGICAL ADAPTATION
CARBON 14 COMPOUNDS
CONCENTRATION RATIO
FIELD TESTS
FOLIAR UPTAKE
LEAVES
PHOSPHOLIPIDS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
WATER
AMINES
AMINO ACIDS
AMMONIUM COMPOUNDS
CARBOXYLIC ACIDS
CEREALS
DRUGS
ESTERS
GRAMINEAE
GRASS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIPIDS
LIPOTROPIC FACTORS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OXYGEN COMPOUNDS
PLANTS
QUATERNARY COMPOUNDS
SYNTHESIS
TESTING
UPTAKE
550201* - Biochemistry- Tracer Techniques
553000 - Agriculture & Food Technology