Blancaflor EB, Jones DL, Gilroy S
Biology Department, 208 Mueller Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802 (E.B.B., S.G.).
Plant Physiol. 1998 Sep;118(1):159-72. doi: 10.1104/pp.118.1.159.
Although Al is one of the major factors limiting crop production, the mechanisms of toxicity remain unknown. The growth inhibition and swelling of roots associated with Al exposure suggest that the cytoskeleton may be a target of Al toxicity. Using indirect immunofluorescence microscopy, microtubules and microfilaments in maize (Zea mays L.) roots were visualized and changes in their organization and stability correlated with the symptoms of Al toxicity. Growth studies showed that the site of Al toxicity was associated with the elongation zone. Within this region, Al resulted in a reorganization of microtubules in the inner cortex. However, the orientation of microtubules in the outer cortex and epidermis remained unchanged even after chronic symptoms of toxicity were manifest. Auxin-induced reorientation and cold-induced depolymerization of microtubules in the outer cortex were blocked by Al pretreatment. These results suggest that Al increased the stability of microtubules in these cells. The stabilizing effect of Al in the outer cortex coincided with growth inhibition. Reoriented microfilaments were also observed in Al-treated roots, and Al pretreatment minimized cytochalasin B-induced microfilament fragmentation. These data show that reorganization and stabilization of the cytoskeleton are closely associated with Al toxicity in maize roots.
虽然铝是限制作物产量的主要因素之一，但其毒性机制仍不清楚。与铝暴露相关的根系生长抑制和肿胀表明，细胞骨架可能是铝毒性的靶点。利用间接免疫荧光显微镜，观察了玉米（Zea mays L.）根中的微管和微丝，并将它们的组织和稳定性变化与铝毒性症状相关联。生长研究表明，铝毒性部位与伸长区有关。在该区域内，铝导致内皮层微管重新排列。然而，即使在毒性慢性症状出现后，外皮层和表皮中的微管方向仍保持不变。铝预处理阻止了生长素诱导的外皮层微管重新定向和冷诱导的微管解聚。这些结果表明，铝增加了这些细胞中微管的稳定性。铝在外皮层的稳定作用与生长抑制相一致。在铝处理的根中也观察到微丝重新定向，并且铝预处理使细胞松弛素B诱导的微丝断裂最小化。这些数据表明，细胞骨架的重新组织和稳定与玉米根中的铝毒性密切相关。
