Zakir Hossain A K M, Koyama Hiroyuki, Hara Tetsuo
Laboratory of Plant Cell Technology, Department of Biotechnology, Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu-shi, Japan.
J Plant Physiol. 2006 Jan;163(1):39-47. doi: 10.1016/j.jplph.2005.02.008.
The present study was conducted to investigate the cell wall properties in two wheat (Triticum aestivum L.) cultivars differing in their sensitivity to Al stress. Seedlings of Al-resistant, Inia66 and Al-sensitive, Kalyansona cultivars were grown in complete nutrient solutions for 4 days and then subjected to treatment solutions containing Al (0, 50 microM) in a 0.5 mM CaCl(2) solution at pH 4.5 for 24 h. Root elongation was inhibited greatly by the Al treatment in the Al-sensitive cultivar compared to the Al-resistant cultivar. The Al-resistant cultivar accumulated less amount of Al in the root apex than in the Al-sensitive cultivar. The contents of pectin and hemicellulose in roots were increased with Al stress, and this increase was more conspicuous in the Al-sensitive cultivar. The molecular mass of hemicellulosic polysaccharides was increased by the Al treatment in the Al-sensitive cultivar. The increase in the content of hemicellulose was attributed to increase in the contents of glucose, arabinose and xylose in neutral sugars. Aluminum treatment increased the contents of ferulic acid and p-coumaric acid especially in the Al-sensitive cultivar by increasing the activity of phenylalanine ammonia lyase (PAL, EC 4.3.1.5). Aluminum treatment markedly decreased the beta-glucanase activity in the Al-sensitive cultivar, but did not exert any effect in the Al-resistant cultivar. These results suggest that the modulation of the activity of beta-glucanase with Al stress may be involved in part in the alteration of the molecular mass of hemicellulosic polysaccharides in the Al-sensitive cultivar. The increase in the molecular mass of hemicellulosic polysaccharides and ferulic acid synthesis in the Al-sensitive cultivar with Al stress may induce the mechanical rigidity of the cell wall and inhibit the elongation of wheat roots.
本研究旨在调查两个对铝胁迫敏感性不同的小麦（Triticum aestivum L.）品种的细胞壁特性。耐铝品种Inia66和铝敏感品种Kalyansona的幼苗在完全营养液中培养4天，然后在pH 4.5的0.5 mM CaCl₂溶液中，用含铝（0、50 microM）的处理溶液处理24小时。与耐铝品种相比，铝处理对铝敏感品种的根伸长有极大的抑制作用。耐铝品种根尖积累的铝量比铝敏感品种少。根中果胶和半纤维素的含量随铝胁迫增加，且这种增加在铝敏感品种中更明显。铝处理使铝敏感品种中半纤维素多糖的分子量增加。半纤维素含量的增加归因于中性糖中葡萄糖、阿拉伯糖和木糖含量的增加。铝处理尤其在铝敏感品种中通过提高苯丙氨酸解氨酶（PAL，EC 4.3.1.5）的活性增加了阿魏酸和对香豆酸的含量。铝处理显著降低了铝敏感品种中的β-葡聚糖酶活性，但对耐铝品种没有任何影响。这些结果表明，铝胁迫下β-葡聚糖酶活性的调节可能部分参与了铝敏感品种中半纤维素多糖分子量的改变。铝胁迫下铝敏感品种中半纤维素多糖分子量的增加和阿魏酸合成可能诱导细胞壁的机械刚性并抑制小麦根的伸长。
