The effect of methionine, ethylene and polyamine catabolic intermediates on polyamine accumulation in detached soybean leaves

Abstract

In the present study we determined the effects of methionine, intermediates of polyamine catabolic pathways and inhibitors of either ethylene biosynthetic or polyamine catabolic pathways on polyamine accumulation in soybean leaves. Inhibitors to SAM decarboxylase and spermidine synthase, methylglyloxal‐bis‐(guanylhy‐drazone) and cyclohexylamine, respectively, suggest that methionine may provide aminopropyl groups for the synthesis of polyamine via S‐adenosylmethionine (SAM). Results from experiments that utilized a combination of compounds which altered either ethylene or polyamine biosynthesis, namely, aminoethoxyvinyl glycine, CoSO4, 2,5‐norbornadiene, and CuSO4, suggest the two pathways compete for a common precursor. However, exogenous addition of ethylene (via ethephon treatments) had little or no effect on polyamine biosynthesis. Likewise, polyamine treatments had little or no effect on ethylene biosynthesis. These data suggest that there are few or no inhibitory effects from the end products of one pathway on the synthesis of the other. Data from leaves treated with metabolic intermediates in the catabolic pathway of polyamines and inhibitors of enzymes in the catabolic pathway, i.e. aminoguanidine, hydroxyethyldrazine and gabaculine, suggest that the observed increases in polyamine titers were not due to decreased catabolism of the polyamines. One catabolic intermediate, γ‐aminobutyric acid (GABA), elevated putrescine, spermidine and spermine by 12‐, 1.4‐, and 2‐fold, respectively, Ethylene levels decreased (25%) in GABA‐treated leaves. This small decrease in ethylene could not account for such large increase in putrescine titers. Further analysis demonstrated that the GABA‐mediated polyamine accumulation was inhibited by difluoromethylarginine, an inhibitor of arginine decarboxylase, but not by difluoromethylornithine, an inhibitor of ornithine decarboxylase. These data suggest that GABA directly or indirectly affects the biosynthesis of polyamines via arginine decarboxylase.

Content of Phenolic Compounds and Free Polyamines in Black Chokeberry (Aronia melanocarpa) after Application of Polyamine Biosynthesis Regulators

“…This result refers to the mediated relation between the polyamines and saccharides synthesis. It is in accordance with Turano et al (14) and Tiburcio et al (16).…”

Ethylene and polyamine production patterns during in vitro shoot organogenesis of two passion fruit species as affected by polyamines and their inhibitor

“…This suggested that the addition of an inhibitor or final products of the activity of the SAM decarboxylase enzyme favored ethylene biosynthesis. This observation contrasted with those findings reported by Turano et al (1997), working with Glycine max, that suggested that the final products of ethylene and PA biosynthesis exerted little or no effects on the biosynthesis of either regulator.…”

“…In turn, putrescine is converted to spermidine by the addition of an aminopropyl group derived from decarboxylated S-adenosil methionine (SAM) through the activity of spermidine synthase. The addition of another aminopropyl group to spermidine by spermine synthase yields spermine (Turano et al 1997;Andersen et al 1998). SAM is the universal donor in transmethylation reactions; it can be decarboxylated to yield either spermidine and spermine or it can be converted to 1-aminocyclopropane-1-carboxylic acid (ACC) by ACC synthase to produce ethylene via ACC oxidase (Ravanel et al 1998).…”

Nitrate supply induces changes in polyamine content and ethylene production in wheat plants grown with ammonium

“…Other results showed that in tomato fruit, PAs inhibited the accumulation of the transcript of 1-aminocyclopropane-1-carboxilic acid synthase (Li et al, 1992). Likewise, studies using ethylene inhibitors also observed higher levels of PAs (Turano et al, 1997;Arigita et al, 2004). In addition, some authors have shown that decreased ethylene production induces organogenesis and higher Spm and Spd contents (Finlayson and Reid, 1996;Arigita et al, 2004).…”