Biosynthesis of wound ethylene in morning-glory flower tissue
Production of wound ethylene was investigated in rib segments excised from flower buds of morning-glory (Ipomoea tricolor). Segments of the ribs were cut from buds 2 days before flower opening, floated overnight on 5 mM KCl solution, and transferred to agar the following morning. These immature segments evolved only a small quantity of ethylene during incubation on agar, with most of the production occurring in the morning. When such segments were wounded mechanically early in the afternoon, the rate of ethylene production rose more than 10-fold within 1 hour and returned to a low rate after about 3 hours. Production of ethylene by both untreated and wounded rib segments was inhibited more than 95% by overnight pretreatment with the ethoxy analog of rhizobitoxine (3 x 10/sup -5/ and 10/sup -4/ M). After overnight exposure of segments to 9 ..mu..M L-methionine-U-/sup 14/C, the specific radioactivity of the ethylene evolved by untreated and wounded tissue was determined and compared to the specific radioactivities of carbon atoms 3 plus 4 of methionine and S-methylmethionine (SMM) extracted from the segments. The specific radioactivity of methionine was about one-half that of SMM; neither value was significantly affected by wounding. The specific radioactivity of ethylene evolved by untreated tissue was close to that of SMM. In wounded tissue the specific radioactivity of the ethylene evolved was lower, but still above that of methionine. These results are consistent with the interpretations that wound ethylene is synthesized from carbon atoms 3 plus 4 of either SMM or methionine. On the basis of earlier experiments with senescing rib segments, it is suggested that methionine serves as the precursor of the wound ethylene.
- Research Organization:
- Michigan State Univ., East Lansing
- OSTI ID:
- 7342747
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 57:4; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AGAR
ALKALI METAL COMPOUNDS
ALKENES
AMINO ACIDS
ANIMALS
BIOSYNTHESIS
BUDS
CARBOHYDRATES
CARBOXYLIC ACIDS
CHLORIDES
CHLORINE COMPOUNDS
COLLOIDS
DISPERSIONS
ETHYLENE
FLOWERS
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
INCUBATION
INJURIES
JUVENILES
LIPOTROPIC FACTORS
METHIONINE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
POLYSACCHARIDES
POTASSIUM CHLORIDES
POTASSIUM COMPOUNDS
PRECURSOR
SACCHARIDES
SYNTHESIS
WOUNDS