Inhibition of Ethylene Biosynthesis by Aminoethoxyvinylglycine and by Polyamines Shunts Label from 3,4-[¹⁴C]Methionine into Spermidine in Aged Orange Peel Discs

Abstract

The flux of radioactivity from 3,4-114Clmethionine into S-adenosyl_L-methionine (SAM), 1-aminocyclopropane-l-carboxylic acid (ACC), sperm- (11), and by wounded tissue of citrus fruit (12, 29) has been previously reported. The induction of ethylene formation by ABA and the inhibitory effect of AVG on its production in citrus bud culture and leaf explants were also studied (10, 21). In the present investigation, we have used orange peel tissue to study relative incorporation of radioactivity from 3,4-[14CJmethionine into SAM, ACC, spermine, and spermidine while inhibiting biosynthesis of ethylene from ACC by cobalt and phosphate ions. By specifically inhibiting the terminal step of ethylene biosynthesis (Fig. 1)

Decreased Ethylene Biosynthesis, and Induction of Aerenchyma, by Nitrogen- or Phosphate-Starvation in Adventitious Roots of Zea mays L.

“…2-4) which was maintained for each successive whorl of adventitious roots that emerged from the stem base for the duration of the starvation treatment (up to 24 d). Our results may seem to be at variance with those of others (6,14) who found that it was the presence of phosphate that inhibited ethylene biosynthesis in a wide range of higher plant tissues, including carrot root and etiolated stem segments of pea (Pisum sativum) and tomato (Lycopersicon esculentum). Inhibition of ethylene production by phosphate also takes place in fruit tissues (6,14) where it acts on the conversion of ACC to ethylene (14).…”

“…Our results may seem to be at variance with those of others (6,14) who found that it was the presence of phosphate that inhibited ethylene biosynthesis in a wide range of higher plant tissues, including carrot root and etiolated stem segments of pea (Pisum sativum) and tomato (Lycopersicon esculentum). Inhibition of ethylene production by phosphate also takes place in fruit tissues (6,14) where it acts on the conversion of ACC to ethylene (14). However, the concentrations of phosphate that were used were high (50-100 mM), greatly in excess of those that plant roots would encounter under physiological conditions; commonly, hydro- (Fig.…”

“…Likewise, in the hypoxic intemodes of submerged, deep water rice, promotion of ethylene synthesis was accompanied by enhancement of ACC synthase activity (7, Although not all the components of the ethylene biosynthetic pathway have been examined in maize roots, there is sufficient information from characterization of ACC, ACC synthase, and EFE (this paper and ref. 2), as well as the action of the inhibitor of ACC synthase (AVG) (18,21) to assume that essentially the same pathway from methionine to ethylene is followed in maize roots as in many other plant tissues especially fruits that have been more fully described (14,15,26,31). The present results can therefore be examined in relation to what is known concerning the regulation of this pathway in other plant tissues.…”

“…SAM is recognized to be a precursor for both the ethylene biosynthetic pathway, and for formation of spermidine and other polyamines (26,30). Inhibition of the conversion of SAM to ACC in orange peel discs shunted SAM into spermidine (14). It would be interesting to know whether nutrient deprivation of maize roots stimulates diversion of SAM to polyamines rather than ethylene biosynthesis.…”

Effects of Exogenous 1,3-Diaminopropane and Spermidine on Senescence of Oat Leaves

“…According to Apelbaum et al (4) and Suttle (27), PAs inhibit ethylene biosynthesis primarily by inhibiting ACC conversion to ethylene. Other investigators found evidence for an inhibition at the conversion of SAM to ACC (8).…”