Galston A W, Sawhney R K
Department of Biology, Yale University, New Haven, Connecticut 06511-8112.
Plant Physiol. 1990 Oct;94(2):406-10. doi: 10.1104/pp.94.2.406.
The diamine putrescine, the triamine spermidine, and the tetramine spermine are ubiquitous in plant cells, while other polyamines are of more limited occurrence. Their chemistry and pathways of biosynthesis and metabolism are well characterized. They occur in the free form as cations, but are often conjugated to small molecules like phenolic acids and also to various macromolecules. Their titer varies from approximately micromolar to more than millimolar, and depends greatly on environmental conditions, especially stress. In cereals, the activity of one of the major polyamine biosynthetic enzymes, arginine decarboxylase, is rapidly and dramatically increased by almost every studied external stress, leading to 50-fold or greater increases in putrescine titer within a few hours. The physiological significance of this increase is not yet clear, although most recent work suggests an adaptive, protective role. Polyamines produced through the action of ornithine decarboxylase, by contrast, seem essential for DNA replication and cell division. The application of exogenous polyamines produces effects on patterns of senescence and morphogenesis, suggesting but not proving a regulatory role for polyamines in these processes. The evidence for such a regulatory role is growing.
二胺腐胺、三胺亚精胺和四胺精胺在植物细胞中普遍存在，而其他多胺的分布则较为有限。它们的化学性质以及生物合成和代谢途径已得到充分表征。它们以阳离子的形式以游离态存在，但常常与小分子如酚酸以及各种大分子结合。它们的浓度从大约微摩尔到超过毫摩尔不等，并且在很大程度上取决于环境条件，尤其是胁迫。在谷物中，几乎每种研究过的外部胁迫都会使主要多胺生物合成酶之一精氨酸脱羧酶的活性迅速且显著增加，导致腐胺浓度在数小时内增加50倍或更多。尽管最近的大多数研究表明其具有适应性保护作用，但这种增加的生理意义尚不清楚。相比之下，通过鸟氨酸脱羧酶作用产生的多胺似乎对DNA复制和细胞分裂至关重要。外源多胺的应用会对衰老和形态发生模式产生影响，这表明多胺在这些过程中具有调节作用，但尚未得到证实。支持这种调节作用的证据正在增加。
