低磷供应对拟南芥根系构型的影响

在人工气候箱中，采用Johnson培养基对拟南芥在低磷供应条件下根系构型的变化进行了研究，结果表明：拟南芥在磷饥饿诱导下，主根缩短，侧根密度、根毛的数量和长度显著增加，并且，根尖到第一侧根和第一根毛的距离也大大缩短。这些改变增加了根系比表面积，并且使得根系分布更加靠近土壤表层，有利于提高植物吸收土壤中有机磷的效率。低磷胁迫还导致拟南芥根系分生组织区细胞形状变异，柱细胞数量减少；主根生长和细胞伸长的动力学分析显示，磷饥饿促使拟南芥主根生长变缓，细胞长度随磷饥饿程度的加深迅速缩小。CycB1;1:GUS染色分析结果表明，低磷破坏拟南芥根系分生组织细胞分裂能力，这些结果说明磷胁迫同时抑制了细胞的伸长和分裂，从而引起拟南芥主根的缩短。

Effect of Low-phosphate Supply on the Root System Architecture in Arabidopsis thaliana

Using Johnson medium, under climatic chamber condition, we detected the change of root architecture under Pi starvation in Arabidopsis. Results showed that the P deficiency inhibited primary root growth, enhanced lateral root concentration and stimulated root hair elongation and root hair proliferation. Moreover, P-starvation decreases the distance from root tip to first lateral root primordium and to first root hair. These changes increased the root specific surface area and distributed the root system closer to soil surface, therefore enhanced the absorption ability of root. P starvation also induced the cell distortion， arrested columella cells development. The kinetic assays on cell length and primary root growth showed a reduction in the primary root elongation and in the cell length when compared with high P-grown plants. CycB1;1:GUS staining suggested that P-starvation destroyed cell division in root meristem. Therefore, the reduced primary root growth was due to the reduced cell elongation and cell division.