Transgenic manipulation of the metabolism of polyamines in poplar cells
Transgenic manipulation of the metabolism of polyamines in poplar cells
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DOI：
10.1104/pp.125.4.2139
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发表时间：
2001-04-01
期刊：
影响因子：
7.4
通讯作者：
Minocha, SC
中科院分区：
文献类型：
--
作者：
Bhatnagar, P;Glasheen, BM;Minocha, SC
多胺（腐胺，亚精胺和精胺）的代谢已成为遗传操作的目标，因为它们在植物发育和可能的胁迫耐受性的重要性。我们研究了多胺代谢的非转基因（NT）和转基因细胞的白杨（黑杨x maximowiczii）表达小鼠Orn脱羧酶（odc）的cDNA。与NT细胞相比，转基因细胞显示小鼠ODC酶活性水平升高，腐胺含量增加数倍，精脒含量略有增加，精胺含量略有减少。标记的鸟氨酸（Orn）转化为腐胺显着高于在转基因细胞比NT。而外源性供应的OM引起细胞腐胺在两个细胞系中的增加，高浓度的精氨酸是抑制腐胺积累。添加尿素和谷氨酰胺对两种细胞系中的多胺均无影响。甲硫氨酸亚砜亚胺谷氨酰胺合成酶的抑制导致腐胺和亚精胺在两个细胞系中的大幅减少。结果表明：（a）异源Ode基因的转基因表达可用于调节植物细胞中的腐胺代谢，（B）腐胺的大量积累不影响天然精氨酸脱羧酶活性，（c）Orn生物合成主要由谷氨酰胺/谷氨酸盐而不是由精氨酸的分解代谢分解发生，（d）Orn生物合成可能成为Odc转基因细胞中腐胺产生的限制因素，和（e）氮同化成谷氨酰胺与其用于腐胺生产的需求增加保持同步。
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 x 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 Om 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 ode 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.