中文摘要：

以紫花苜蓿为材料，探讨了铝对根伸长、根毛变形、结瘤和苜蓿根瘤菌（Rhizobium meliloti）生长的影响，旨在阐明豆科作物共生结瘤的初期铝毒害的机制。结果显示，在3、6、9μmol·L^-1 AlCl3，处理24h后，初生根相对伸长率分别为对照（不加铝）的78．4％、43．1％和26．8％，根瘤菌的活菌数分别比对照减少了47．37％、63．16％和84．21％；在不接种根瘤菌而添加结瘤因子的情况下，苜蓿结瘤初期根毛对结瘤信号的应答反应-根毛变形的比率降低了44．59％、71．43％和80．09％，而在缺乏结瘤因子的情况下，铝对根毛变形无显著的影响；在接种根瘤菌条件下，用2、3、4、5、6μmol·L^-1 Al处理48h后，根毛变形率分别减少了24．54％、33．18％、51．82％、63．05％和67．86％。这些结果说明，在铝胁迫下根毛变形受阻可能是铝抑制结瘤信号传递的结果。

英文摘要：

To elucidate the mechanisms of the toxicity of Al to leguminous plants at initial stages of symbiotic nodulation, the effects of Al on the growth of primary root, root hair deformation （RHD）, nodulation of Medicago sativa L. and the growth of Rhizobium melilot （R. meliloti） were investigated in this study. After treatment with 3, 6 and 9μmol·L^-1 Al for 24 h, the relative elongation of primary roots was just 78.4%, 43.1% and 26.8% of the contrast （-Al）, moreover, the live R. meliloti cells reduced by 47.37%, 63.16%, 84.21%, respectively. Furthermore, in the absence of R. meliloti but in the presence of Nod factors （NF）, the RHD, which indicated root hairs responce to nodulation signal at ini- tial stages of nodulation on Medicago sativa L., was depressed by 44.6%, 71.4% and 80.1%, respectively. However, in the absence of NF, there was no prominent effect on RHD by Al. The RHD reduced by 24.54%, 33.18%, 51.82%, 63.05% and 67.86%, respectively after the roots inoculated R. meliloti were treated for 48 h with 2, 3, 4, 5 and 6 μmol·L^-1 Al. These results suggested that the inhibition of RHD might be the result of Al suppressing the transduction of nodulation signal.