多胺生物合成抑制剂D-精氨酸对拟南芥幼苗根系生长的影晌

为探讨多胺生物合成抑制剂D-精氨酸（D-arginine，D-Arg）对拟南芥根系生长的影响，首先用腐胺（0．1mmol‘L-1）和D—Arg（1．0mmol·L-1）处理种子萌发后生长2d的拟南芥幼苗。腐胺（0．1mmol·L-1）显著促进主根伸长，D-Arg（1．0mmol-L-1）显著抑制主根伸长，并对主根根尖的细胞形态有明显影响。为了进一步了解D—Arg影响拟南芥主根生长的机理，采用浓度梯度D．Arg处理幼苗根系。实验结果表明，随着D-Arg浓度增加（0．2～1．0mmol·L-1），拟南芥幼苗主根生长受抑制的程度越严重。微分干涉观察主根根尖发现，外源施加D—Arg，引起拟南芥主根根尖分生区的细胞数目减少，使拟南芥幼苗表现出主根的伸长生长变缓。当分生区数目较少时，出现主根几乎不再仲长的现象。由此推测，多胺生物合成抑制剂D-Arg对拟南芥幼苗根生长的抑制作用机制，是D-Arg影响了其根尖分生区的细胞分裂活动，使分生区细胞数目减少，从而引起分生区长度减小，最终导致拟南芥主根仲长生长受到抑制。

Effects of Polyamine Biosynthetic Inhibitor D-arginine on Root Growth in Ar- abidopsis thaliana Seedlings

To analysis the effects of polyamine biosynthetic inhibitor D-arginine （D-Arg） on root growth in Ar- abidopsis thaliana, firstly two-day seedlings were treated with 0.1 mmol.L-1 putrescine or 1.0 mmol-L-1 D-Arg. The results showed that putrescine promoted the elongation of main root, while D-Arg inhibited significantly and also had negative effect on the shape of root tip cells. In order to further research the effects of D-Arg on main root development, Arabidopsis seedlings were treated with D-Arg of varying concentrations. The results showed that the degree of inhibition on main root growth was increased with an increase of D-Arg concentra- tion （0.2-1.0 mmol.L-l）. The observation of root tip structure by differential interference microscopy found that D-Arg decreased the cell number of main root meristematic zone and main root growth length in A. thaliana. When the cell number of meristematic zone was very few, main root elongation growth almost stopped. So we conclude that the mechanism of D-Arg treatment resulting in main root growth inhibition is that D-Arg inhibits cell division of meristem leading to cell number of meristem zone reduction and then suppresses the main root elongation growth in A. thaliana.