Abstract: 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.

Key words: Arabidopsis thaliana, low-phosphate supply, physiological mechanism, root system architecture