盐胁迫下大麦根系多胺代谢与其耐盐性的关系

研究了0－300mmol/L NaCl对大麦（Hordeum vulgare L.)幼苗生长速率，根系游离和结合态多胺含量以及多胺生物合成关键酶活性的影响。结果表明，在0－200mmol/L NaCl处理下精氨酸脱羧酶（ADC）、多胺氧化酶（PAO）以及转谷酰胺酶（TGase)活性明显提高，而在300mol/L NaCl处理下活性下降，与之对应，游离腐胺（Put)含量随处理盐浓度的提高一直呈上升趋势。亚精胺（Spd)和在根系内检测到的未知多胺（PAx）在低浓度盐处理时含量上升，随盐浓度的提高含量下降，盐处理前后精胺（Spm)含量变化不明显，低浓度盐处理时游离态（Spd PAx)/Put上升，随盐浓度的提高比值明显下降，结合态Put,Spd和PAx含量以及结合态多胺总量均在低浓度盐处理时上升，随盐浓度的提高含量明显下降，统计分析显示，大麦相对生长速率与游离态（Spd PAx）／Put和结合态多胺含量间均呈极显著正相关关系，与游离态多胺和结合态多胺的比值间均呈显著负相关关系，上述结果说明盐胁迫下大麦体内游离态Spd,PAx与Put以及结合态形式之间的平衡与大麦耐盐性关系密切，游离态Put向Spd,PAx以及结合态形式转化均有利于大麦耐盐性的提高。

Relationship Between Polyamine Metabolism in Roots and Salt Tolerance of Barley Seedlings

Plant growth rate (GR), contents of free polyamines (fPAs) and bound polyamines (bPAs) and activities of some key enzymes involved in polyamine (PA) metabolism in the roots of two barley ( Hordeum vulgare L.) cultivars differing in salt sensitivity were investigated with 0-300 mmol/L NaCl treatments. With 0-200 mmol/L NaCl treatments, activities of arginine decarboxylase (ADC) and transglutaminase (TGase) and PA oxidase (PAO) in the roots of barley seedlings all increased, while TGase and PAO activities decreased slightly at 300 mmol/L NaCl. As a result, free Put (fPut) content increased continuously with increasing concentrations of NaCl, while levels of free Spd (fSpd) and an unknown PA (fPAx) and bPAs (bPut, bSpd and bPAx), as well as (fSpd+fPAx)/fPut ratio rose at 50-200 mmol/L NaCl and reduced at 300 mmol/L NaCl. However, no significant change in the tetra_amine spermine (Spm) content was observed. Statistical analysis showed that GR was very significantly positively correlated with (fSpd+fPAx)/fPut ratios and the contents of bPAs, whereas a significant inverse correlation existed between GR and the ratios of fPA contents to bPA levels. These results showed that, under salt stress, the balance between fSpd, fPAx and fPut levels and an equipoise between fPA and bPA contents in roots were important to salt tolerance of barley seedlings.