Graduate School of Natural Science and Technology, Okayama University, 700-8530 Okayama, Japan.
Ann Bot. 2010 Jan;105(1):1-6. doi: 10.1093/aob/mcp259.
Polyamines are small polycationic molecules found ubiquitously in all organisms and function in a wide variety of biological processes. In the past decade, molecular and genetic studies using mutants and transgenic plants with an altered activity of enzymes involved in polyamine biosynthesis have contributed much to a better understanding of the biological functions of polyamines in plants.
Spermidine is essential for survival of Arabidopsis embryos. One of the reasons may lie in the fact that spermidine serves as a substrate for the lysine hypusine post-translational modification of the eukaryotic translation initiation factor 5A, which is essential in all eukaryotic cells. Spermine is not essential but plays a role in stress responses, probably through the modulation of cation channel activities, and as a source of hydrogen peroxide during pathogen infection. Thermospermine, an isomer of spermine, is involved in stem elongation, possibly by acting on the regulation of upstream open reading frame-mediated translation.
The mechanisms of action of polyamines differ greatly from those of plant hormones. There remain numerous unanswered questions regarding polyamines in plants, such as transport systems and polyamine-responsive genes. Further studies on the action of polyamines will undoubtedly provide a new understanding of plant growth regulation and stress responses.
多胺是在所有生物中普遍存在的小多阳离子分子，在多种生物过程中发挥作用。在过去的十年中，使用涉及多胺生物合成的酶活性改变的突变体和转基因植物的分子和遗传研究，对更好地理解多胺在植物中的生物学功能做出了重要贡献。
亚精胺对于拟南芥胚胎的生存是必不可少的。原因之一可能在于亚精胺作为真核翻译起始因子 5A 的赖氨酸hypusine 翻译后修饰的底物，在所有真核细胞中都是必不可少的。精胺不是必需的，但在应激反应中发挥作用，可能通过调节阳离子通道活性，以及在病原体感染时作为过氧化氢的来源。热精胺，精胺的异构体，参与茎伸长，可能通过作用于上游开放阅读框介导的翻译的调节。
多胺的作用机制与植物激素有很大的不同。关于植物中的多胺，还有许多悬而未决的问题，例如运输系统和多胺响应基因。对多胺作用的进一步研究无疑将为植物生长调控和应激反应提供新的认识。
