中文摘要：

以耐铝性明显差异的两个大豆（Glycme max）基因型‘浙秋2号’（耐性）和‘浙春3号’（敏感）为材料，研究根尖边缘细胞比活度、粘液分泌和根长对铝胁迫和解除胁迫的反应，明确边缘细胞的粘液分泌对策在铝毒环境中的生态学意义。结果表明，‘浙秋2号’在100～400μmol·L^-1 Al^3＋处理的3～12h，边缘细胞比活率呈递减趋势，12h后比活率又略有上升。‘浙春3号’在300和400μmol·L^-1 Al^3＋处理的变化与前者一致。两个大豆基因型的粘液层随着Al^3＋浓度增加和时间延长而增厚，并于400μmol·L^-1 Al^3＋处理24h时达到最大（〉17μm）。‘浙秋2号’在低浓度Al^3＋（100和200μmol·L^-1）处理3～6h后就会分泌大量粘液，‘浙春3号’则在300μmol·L^-1Al^3＋处理12h后才有类似的变化。‘浙秋2号’在400μmol·L^-1Al^3＋处理下的根相对伸长率均高于100-300μmol·L^-1 Al^3＋处理，‘浙春3号’则表现为Al^3＋浓度越高，根伸长受抑越明显。Al^3＋胁迫解除后，‘浙秋2号’的粘液分泌速度和分泌量急剧下降，‘浙春3号’在胁迫解除后的24h，仍会持续、大量地分泌粘液（〉19μm）。可见，耐性大豆通过在铝胁迫初期快速、大量地分泌粘液以维持较高的边缘细胞活性和解除胁迫后迅速降低粘液的分泌速度及分泌量来适应铝毒害环境。

英文摘要：

Aims Border cells and their secretory mucilage can form a layer over the surface of younger parts of roots to help form a ＂rhizosheath＂ protecting the root tip from biotic and abiotic stresses. Our objective was to investigate the ecological role of mucilage secretion strategies in response to Al exposure and absence. Methods Soybean （Glycine max） ‘Zheqiu No. 2＇ and ‘Zhechun No. 3＇ were used in this study. Seedlings were aeroponically cultured in 0.2 mmol·L^-1 CaCl2 solution, pH 4.5, containing 0, 100, 200, 300 or 400 μmol·L^-1 AlCl3. Half of the seedlings were harvested after 24 h Al exposure and the other half continued to culture in the absence of Al^3＋. We measured percent viability of border cells, mucilage thickness and relative root elongation. Important findings Percent viability of root border cells decreased with increasing external Al^3＋ concentrations in both cultivars. Percent viability of ＇Zheqiu No. 2＇ border cells decreased slightly after a 3-12 h treatment with 100, 200, or 400 μmol·L^-1 Al^3＋ and then slightly increased with treatment time, whereas the same change in ＇Zhechun No. 3＇ seedlings was noted at Al^3＋ concentrations of 300 and 400 μmol·L^-1. Al^3＋ induced a thicker mucilage layer around border cells of both cultivars, with a maximum of 17 μm after 24 h at 400 μmol·L^-1 Al^3＋. ＇Zheqiu No. 2＇ border cells developed a thicker mucilage layer within 3-6 h in response to 100 and 200 μmol·L^-1 Al^3＋, while ＇Zhechun No. 3＇ cells exhibited the same change after 12 h to 300 μmol·L^-1 Al^3＋. Relative root elongation of ＇Zheqiu No. 2＇ exposed to 400μmol·L^-1 A13＋ was significantly higher than to 100-300 μmol·L^-1 Al^3＋ treatment, while ＇Zhechun No. 3＇ exhibited reduced relative root elongation after exposure to 100-400 μmol·L^-1 Al^3＋. With Al^3＋ recovery treatment, ＇Zheqiu No. 2＇ border cells developed a thinner layer of mucilage in the absence of Al^3＋ compared with Al^3＋ exposure, while ＇Zhechun No