Abstract The addition of 1.5 mM putrescine to the culture
medium facilitated the conversion of protocorm-like bodies
(PLBs) of Dendrobium officinale to shoots. The administration
of 1.0 mM of the polyamine inhibitor, a-DL-difluoromethylarginine,
decreased the conversion of PLBs to
shoots. Compared to the control, the PLBs treated with
1.5 mM putrescine had higher levels of total intracellular
free polyamines. The enhanced conversion of PLBs to shoots
following the addition of putrescine was accompanied by
an increase in the ratio of total cytokinins (CTKs) to indole-
3-acetic acid (IAA). Analysis of enzyme activities indicated
that the increased endogenous level of total CTKs
driven by putrescine was associated with the inhibition of
CTK decomposition by CTK oxidase, while the decreased
endogenous level of IAA was associated with the promotion
of IAA decomposition by IAA oxidase. In addition, putrescine
increased the ratio of reduced glutathione to oxidized
glutathione in the conversion process of PLBs to shoots.
Keywords Endogenous hormone Redox status
Shoot development
Abbreviations
CTKs Cytokinins
DFMA a-DL-difluoromethylarginine
GSH Reduced glutathione
GSSG Oxidized glutathione
IAA Indole-3-acetic acid
PLBs Protocorm-like bodies