The expression of cyclin gene cyc1At induced by endogenous IAA promoted the growth of wheat (Triticum aestivum L.) root at phosphorus deficiency. The length of root axis and IAA concentration of wheat increased with the decrease in the level of P supply (Figs.1, 2). The allocation of assimilates to root in reased due to the polar transportation of IAA. The length of root axis under TIBA + low-P supply was markedly lower than low-P supply without TIBA (Table 1), suggesting that the greater length of root axis at low-P supply resulted from the higher endogenous IAA level under low-P. The increase in IAA concentration in root regulated the expression of cyc1At gene (Fig.4), and subsequently promoted the division of meristematic cells and thereby speeded up the extension of roots.%用液培方法研究了缺磷胁迫对小麦(Triticumaestivum L.)根系生长的影响。结果表明，随着介质磷水平的提高，小麦根轴长度和植株生长素浓度均降低。在低磷条件下用生长素极性运输抑制剂三碘苯甲酸(TIBA)处理后，小麦的根轴长度明显降低，表明生长素参与了缺磷小麦根轴生长的调控。缺磷小麦根部生长素浓度的提高诱导了细胞周期蛋白基因cyclAt的表达，促进了根分生组织细胞的分裂并驱动了根的生长。
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