Ethylene Metabolism and Its Possible Physiological Role in Plants

Ethylene-enhanced ethylene oxidation inVicia faba

“…The observations reported here suggest that the increase in AO activity during ripening (Beyer and Blomstrom 1979), abscission (Beyer 1979b), and senescence (Beyer 1977) may be due to an effect of ethylene increasing levels of AO in plant tissue. However, the fababean system with its high AO activity may be atypical, and not representative of other plant systems.…”

“…Similar enzymes occur in the actinomycete, Mycobacterium paraffinicum (De Bont 1975, De Bont and Albers 1976, De Bont et al 1979, De Bont and Harder 1978, Wiegant and De Bont 1980, animals (Ehrenberg et al. 1977, Filser andBolt 1983), and plants (Beyer 1975, Beyer 1977, Beyer 1979a, Beyer 1979b, Beyer 1980, Beyer and Blomstrom 1979, Beyer and Sundin 1978, Dodds and Hall 1982, Dodds et al 1979, Jerie and Hall 1978. In M. paraffinicum, the function of ethylene oxidation is to provide energy and carbon for the growth of this soil-inhabiting organism.…”

“…The basis for this concept stems from the observation by Beyer that both ethylene production and ethylene oxidation increase during floral senescence (Beyer 1977) and tomato ripening (Beyer and Blomstrom 1979). Beyer also demonstrated an increase in AO during abscission (Beyer 1979b).…”

Mechanisms of ethylene action

“…Subsequently it was demonstrated that in Pisum the earliest detectable metabolites in tissue incorporation were ethylene glycol and its glucose conjugate [13] . Subsequent work by Beyer [10] showed that in experiments with Pisum exposed to 1402 H4 only part of the radioactivity trapped in NaOH could be released on acidification, the remainder proving to be ethylene glycol . Since ethylene oxide is converted to ethylene glycol by strong base it seemed likely that ethylene oxide is a primary product in Pisum as in Vicia and this has subsequently been confirmed (Beyer, pers .…”

“…Such correlations have been demonstrated in peas [5,6] , cut carnations [71, morning glory flowers [ 12] and cotton leaf abscission zones [9] . These findings led Beyer [ 10] to suggest that ethylene metabolism may be directly related to the mode of action of the growth regulator (see below p . 162) .…”