Xing Su Guo, Jun Yu Bing, Hau Zhang Wen, Liang Liu You
College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, P.R. China.
Plant Physiol Biochem. 2007 Aug;45(8):560-6. doi: 10.1016/j.plaphy.2007.05.007. Epub 2007 Jun 6.
Polyamines (PAs) are assumed to perform their functions through their oxidative product such as gamma-aminobutyric acid (GABA) formation. However, there is only limited information on the interrelation between PA degradation and GABA accumulation under salt stress. In order to reveal a quantitative correlation between PA oxidation and GABA accumulation, the effects of treatments with different NaCl concentrations, along with aminoguanidine (AG, a specific inhibitor of diamine oxidases (DAO; EC: 1.4.3.6)) and a recovery test from salt stress on endogenous free PAs, gamma-aminobutyric acid (GABA) accumulation and DAO activity were determined in roots of soybean [Glycine max (L.) Merr.] cultivar Suxie-1. The results showed that the levels of putrescine (Put), cadaverine (Cad), and spermidine (Spd) decreased significantly with increasing salt concentrations. This occurred because salt stress strongly promoted DAO activity to stimulate PA degradation. GABA accumulation increased with growing NaCl concentrations, about an 11- to 17-fold increase as compared with the control plants. AG treatment increased the accumulation of endogenous free PAs as a result of a strong retardation of DAO activity, but decreased GABA accumulation. The recovery for 6 days in 1/2 Hoagland solution from 100mM NaCl stress resulted in a decrease in DAO activity, a rebound of PA levels and a simultaneous reduction of GABA content. A close correlation was observed between the changes in DAO activity and GABA accumulation. The results indicated that higher GABA accumulation (about 39%) induced by salt stress could come from PA degradation, suggesting that PAs might perform their functions through GABA formation under salt stress.
多胺（PAs）被认为是通过其氧化产物（如γ-氨基丁酸（GABA）的形成）来发挥功能的。然而，关于盐胁迫下多胺降解与GABA积累之间的相互关系，目前只有有限的信息。为了揭示多胺氧化与GABA积累之间的定量关系，测定了不同NaCl浓度处理、氨基胍（AG，二胺氧化酶（DAO；EC：1.4.3.6）的特异性抑制剂）以及盐胁迫恢复试验对大豆[Glycine max (L.) Merr.]品种苏协1号根系内源性游离多胺、γ-氨基丁酸（GABA）积累和DAO活性的影响。结果表明，随着盐浓度的增加，腐胺（Put）、尸胺（Cad）和亚精胺（Spd）的水平显著降低。这是因为盐胁迫强烈促进了DAO活性，从而刺激了多胺的降解。GABA积累随着NaCl浓度的增加而增加，与对照植株相比增加了约11至17倍。AG处理由于强烈抑制了DAO活性，增加了内源性游离多胺的积累，但降低了GABA的积累。在1/2 Hoagland溶液中从100mM NaCl胁迫下恢复6天，导致DAO活性降低、多胺水平反弹以及GABA含量同时降低。观察到DAO活性变化与GABA积累之间存在密切相关性。结果表明，盐胁迫诱导的较高GABA积累（约39%）可能来自多胺降解，这表明在盐胁迫下多胺可能通过GABA的形成来发挥其功能。
