以抗旱性不同的两个小麦品种（‘晋麦33’和‘温麦8’）（Triticum aestivum cv. Jinmai 33 and Wenmai 8）为材料，研究了干旱胁迫下多胺含量和多胺氧化酶活性的变化。结果表明：旱过程中，幼苗根、叶中腐胺（Put）、亚精胺（Spd）、精胺（Spm）3种多胺含量和多胺氧化酶（PAO）活性先迅速升高，而后下降。与抗旱性弱的‘晋麦33’相比，抗旱性强的品种‘温麦8’幼苗根、叶中Spd、Spm 含量初期升高幅度大，之后下降速率减慢；PAO活性的变化与之相反，‘晋麦33’的PAO活性提高的幅度大于‘温麦8号’。多胺含量和PAO活性在小麦幼苗的根与叶之间呈极显著正相关。干旱初期，小麦根、叶中多胺迅速积累可能是干旱胁迫反应的一个信号，随后较高的Spd、Spm 水平有利于增强小麦幼苗的抗旱性。
Polyamine (PA) plays an important role in the regulation of senescence and stress-resistance of plants. It has been reported that PA accumulated, and the activities of PA-associated enzymes, involving polyamine oxidase (PAO), increased rapidly in leaves under drought stress. However, little is known about the effect of drought stress on PA metabolism of roots. In the present experiment, two wheat cultivar seedlings with different drought-resistances (Triticum aestivum L. cv. Jinmai 33 and Wenmai 8) under sand-cultivation were used to study the relationship between PA metabolism and drought-resistance. The results showed that the relative water content (RWC) of leaves declined gradually during drought stress (without water supply) compared with controls (with water supply during treatment), and the cv. Wenmai 8 (drought-resistant cultivar) could maintain more leaf RWC than cv. Jinmai 33 (drought-susceptible cultivar) after 48 h of drought stress. The PA (Put, Spd, Spm) content and PAO activity in roots and leaves of seedlings increased quickly during drought stress for 12 h. At this time, the contents of putrescine (Put), spermidine (Spd), spermine (Spm) in drought-treated seedlings of cv. Jinmai 33 were 86%, 69%, 50% higher than control in roots, and 71%, 18%, 11% higher in leaves, while in cv. Wenmai 8 these were 91%, 103%, 85% higher in roots, and 78%, 55%, 53% higher in leaves than control, respectively. The change of PAO activity between two cultivars differed, PAO activity in roots and leaves of drought treated seedlings were 47%, 40% in cv. Jinmai 33, and 26%, 10% in cv. Wenmai 8 higher than their control, respectively. Afterwards, the PA (Put, Spd, Spm) content and PAO activity in roots and leaves of seedlings in two cultivars all decreased, which PA did in a slower rate in cv. Wenmai 8. The Put content and PAO activity in roots and leaves of both cultivars, and the contents of Spd and Spm in cv. Jinmai 33 under drought stress, were significantly lower than their control, whereas the Spm and Spd contents in cv. Wenmai 8 were similar with control during drought stress for 48 h. The changing trends of PA content and PAO activity in roots and leaves were similar. A significant positive relationship in PA content and PAO activity was found between roots and leaves. It is suggested that the rapid accumulation of PA might be a signal responding to drought stress at first, and then the higher contents of Spm and Spd in roots and leaves could enhance drought-resistance in wheat seedlings.
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