Lateral root initiation in Arabidopsis:: Developmental window, spatial patterning, density and predictability
Lateral root initiation in Arabidopsis:: Developmental window, spatial patterning, density and predictability
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DOI：
10.1093/aob/mcj604
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发表时间：
2006-05-01
期刊：
影响因子：
4.2
通讯作者：
González, I
中科院分区：
文献类型：
--
作者：
Dubrovsky, JG;Gambetta, GA;González, I
背景和目的控制侧根（LR）发生的基本调控机制仍然知之甚少。本文试图描述LR起始的模式和时间，定义LR起始发生的发育窗口，并解决LR起始是否可预测的问题。方法对清净根制剂中LRs和LRs原基的空间分布规律进行表征。介绍了LRs和LRP密度的新测量方法（LRs和/或LRP的数量除以它们存在的根部分的长度），并通过对突变体aux1-7的比较分析说明了更常用的测量方法的缺点。利用增强子陷阱系J0121在延时实验中监测LR起始，并开发了一种基于等离子体裂解的方法来确定连续lrp之间的中柱鞘细胞数量。关键结果LRP起始严格地发生在肢端，在已经发展的LRs和LRP之间未发现新生起始事件。然而，lrp并没有以类似的模式变成LRs。侧壁器官的纵向间距是可变的，侧壁器官之间的距离与细胞数量和连续lrp起始时间成正比。在靠近原木质部两极的两个中柱鞘细胞锉之间，LR发生有强烈的交替趋势。由于发育缓慢的lrp的出现，lrp密度随着时间的推移而增加，并且在拟南芥个体中似乎是独一无二的。在拟南芥中，LR起始有一个狭窄的发育窗口，并且没有发现特定的细胞计数或距离测量机制来确定连续起始事件的位置。然而，分支密度和侧枝密度（LRs和lrp的密度）是植物特有的，基于后者的密度可以预测连续LRs之间的平均距离。
Background and Aims The basic regulatory mechanisms that control lateral root (LR) initiation are still poorly understood. An attempt is made to characterize the pattern and timing of LR initiation, to define a developmental window in which LR initiation takes place and to address the question of whether LR initiation is predictable.Methods The spatial patterning of LRs and LR primordia (LRPs) on cleared root preparations were characterized. New measures of LR and LRP densities (number of LRs and/or LRPs divided by the length of the root portions where they are present) were introduced and illustrate the shortcomings of the more customarily used measure through a comparative analysis of the mutant aux1-7. The enhancer trap line J0121 was used to monitor LR initiation in time-lapse experiments and a plasmolysis-based method was developed to determine the number of pericycle cells between successive LRPs.Key Results LRP initiation occurred strictly acropetally and no de novo initiation events were found between already developed LRs or LRPs. However, LRPs did not become LRs in a similar pattern. The longitudinal spacing of lateral organs was variable and the distance between lateral organs was proportional to the number of cells and the time between initiations of successive LRPs. There was a strong tendency towards alternation in LR initiation between the two pericycle cell files adjacent to the protoxylem poles. LR density increased with time due to the emergence of slowly developing LRPs and appears to be unique for individual Arabidopsis accessions.Conclusions. In Arabidopsis there is a narrow developmental window for LR initiation, and no specific cell-count or distance-measuring mechanisms have been found that determine the site of successive initiation events. Nevertheless, the branching density and lateral organ density (density of LRs and LRPs) are accession-specific, and based on the latter density the average distance between successive LRs can be predicted.