Transgenic Manipulation of the Metabolism of Polyamines in Poplar Cells1
The metabolism of polyamines (putrescine, spermidine, and spermine) has become the target of genetic manipulation because of their significance in plant development and possibly stress tolerance. We studied the polyamine metabolism in non-transgenic (NT) and transgenic cells of poplar ( Populus nigr...
Saved in:
Published in | Plant physiology (Bethesda) Vol. 125; no. 4; pp. 2139 - 2153 |
---|---|
Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
American Society of Plant Physiologists
01.04.2001
|
Online Access | Get full text |
Cover
Loading…
Summary: | The metabolism of polyamines (putrescine, spermidine, and spermine)
has become the target of genetic manipulation because of their
significance in plant development and possibly stress tolerance. We
studied the polyamine metabolism in non-transgenic (NT) and transgenic
cells of poplar (
Populus nigra
×
maximowiczii
) expressing a mouse Orn decarboxylase
(
odc
) cDNA. The transgenic cells showed elevated levels
of mouse ODC enzyme activity, severalfold higher amounts of putrescine,
a small increase in spermidine, and a small reduction in spermine as
compared with NT cells. The conversion of labeled ornithine (Orn) into
putrescine was significantly higher in the transgenic than the NT
cells. Whereas exogenously supplied Orn caused an increase in cellular
putrescine in both cell lines, arginine at high concentrations was
inhibitory to putrescine accumulation. The addition of urea and
glutamine had no effect on polyamines in either of the cell lines.
Inhibition of glutamine synthetase by methionine sulfoximine led to a
substantial reduction in putrescine and spermidine in both cell lines.
The results show that: (a) Transgenic expression of a heterologous
odc
gene can be used to modulate putrescine metabolism
in plant cells, (b) accumulation of putrescine in high amounts does not
affect the native arginine decarboxylase activity, (c) Orn biosynthesis
occurs primarily from glutamine/glutamate and not from catabolic
breakdown of arginine, (d) Orn biosynthesis may become a limiting
factor for putrescine production in the
odc
transgenic
cells, and (e) assimilation of nitrogen into glutamine keeps pace with
an increased demand for its use for putrescine production. |
---|---|
Bibliography: | Corresponding author; e-mail sminocha@christa.unh.edu; fax 603–862–3784. |
ISSN: | 0032-0889 1532-2548 |