Methionine metabolism and ethylene formation in etiolated pea stem sections
Stem sections of etiolated pea seedlings (Pisum sativum L. cv. Alaska) were incubated overnight on tracer amounts of L-(U-/sup 14/C)methionine and, on the following morning, on 0.1 millimolar indoleacetic acid to induce ethylene formation. Following the overnight incubation, over 70% of the radioactivity in the soluble fraction was shown to be associated with S-methylmethionine (SMM). The specific radioactivity of the ethylene evolved closely paralleled that of carbon atoms 3 and 4 of methionine extracted from the tissue and was always higher than that determined for carbon atoms 3 and 4 of extracted SMM. Overnight incubation of pea stem sections on 1 millimolar methionine enhanced indoleacetic acid-induced ethylene formation by 5 to 10%. Under the same conditions, 1 millimolar homocysteine thiolactone increased ethylene synthesis by 20 to 25%, while SMM within a concentration range of 0.1 to 10 millimolar did not influence ethylene production. When unlabeled methionine or homocysteine thiolactone was applied to stem sections which had been incubated overnight in L-(U-/sup 14/C)methionine, the specific radioactivity of the ethylene evolved was considerably lowered. Application of unlabeled SMM reduced the specific radioactivity of ethylene only slightly.
- Research Organization:
- Michigan State Univ., East Lansing
- DOE Contract Number:
- EY-76-C-02-1338
- OSTI ID:
- 5504200
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 63:4; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACETIC ACID
ALKENES
ALKYL RADICALS
AMINO ACIDS
AZOLES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOSYNTHESIS
CARBON 14
CARBON ISOTOPES
CARBOXYLIC ACIDS
DOSE-RESPONSE RELATIONSHIPS
ESTERS
ETHYLENE
EVEN-EVEN NUCLEI
FOOD
HETEROCYCLIC COMPOUNDS
HOMOCYSTEINE
HYDROCARBONS
INDOLES
ISOTOPES
LACTONES
LIGHT NUCLEI
LIPOTROPIC FACTORS
METABOLISM
METHIONINE
METHYL RADICALS
MONOCARBOXYLIC ACIDS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PEAS
PLANT STEMS
PYRROLES
RADICALS
RADIOISOTOPES
RESPONSE MODIFYING FACTORS
SYNTHESIS
THIOLS
VEGETABLES
YEARS LIVING RADIOISOTOPES