Gemperlová L., Nováková M., Vaňková R., Eder J., Cvikrová M
JOURNAL OF EXPERIMENTAL BOTANY
57:
1413-1421,
2006
Klíčová slova:
Arginine decarboxylase, diamine oxidase, ornithine
Abstrakt:
Changes in the contents of polyamines (PAs) in
tobacco leaves (Nicotiana tabacum L. cv. Wisconsin
38) grown under 16 h photoperiod were correlated with
arginine and ornithine decarboxylase (EC 4.1.1.19 and
EC 4.1.1.17) and diamine oxidase (EC 1.4.3.6) activities.
The maximum of free and soluble conjugated forms of
PAs occurred 1–2 h after the middle of the light period
and was followed by two distinct peaks at the end of
the light and at the beginning of the dark phase.
Putrescine was the most abundant and cadaverine
the least abundant PA in both free and PCA-soluble
forms. However, cadaverine was predominant in PCAinsoluble
conjugates, followed by putrescine, spermidine,
and spermine. Both arginine and ornithine
decarboxylases are involved in putrescine biosynthesis
in tobacco leaves. Light dramatically stimulated the
activity of ornithine decarboxylase, while no photoinduction
of arginine decarboxylase activity was observed.
Ornithine decarboxylase was found mainly in
the particulate fraction. Only one peak, just after light
induction, occurred in the cytosolic fraction, with 35%
of the total ornithine decarboxylase activity. By contrast,
the total arginine decarboxylase activity was
equally divided between the soluble and pellet fractions.
A sharp increase in diamine oxidase activity
occurred 1 h after exposure to light, concomitant with
the light-induced increase in ornithine decarboxylase
activity. After a decline, diamine oxidase activity increased
again, together with the rise in the amount of
free Put. The roles of both conjugation of PAs with
hydroxycinnamic acids and oxidative degradation of
putrescine in maintaining free PA levels during the
24 h light/dark cycle are discussed. The presented
results have shown that the parameters studied here
followed rhythmical changes and were not only affected
by light.
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