Pluripotency of Arabidopsis xylem pericycle underlies shoot regeneration from root and hypocotyl explants grown in vitro
Pluripotency of Arabidopsis xylem pericycle underlies shoot regeneration from root and hypocotyl explants grown in vitro
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DOI：
10.1111/j.1365-313x.2008.03715.x
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发表时间：
2009-02-01
期刊：
影响因子：
7.2
通讯作者：
Chriqui, Dominique
中科院分区：
文献类型：
--
作者：
Atta, Ramzy;Laurens, Lieve;Chriqui, Dominique
我们已经建立了一个详细的框架，从拟南芥根和下胚轴外植体在体外生长的芽再生的过程。使用其中GUS或GFP基因与发育基因的启动子融合的转基因植物系（WUS、CLV 1、CLV 3、STM、CUC 1、PLT 1、RCH 1、QC 25），或编码生长素应答（DR 5）或转运（PIN 1）、细胞分裂素（CK）应答（ARR 5）或合成（IPT 5）或有丝分裂活性（CYCB 1）的指示物的基因的启动子，结果表明，再生芽直接或间接起源于邻近木质部极的周鞘细胞。此外，芽再生似乎部分类似于侧根分生组织（LRM）的形成。在富含2，4-二氯苯氧乙酸（2，4-D）的愈伤组织诱导培养基（CIM）上预培养期间，木质部周壁再活化建立了不是真正愈伤组织但具有LRM的许多特征的副产物。转移到一个CK丰富的芽诱导培养基（SIM）导致早期LRM样原基改变拍摄分生组织。直接起源的芽从木质部周发生后，直接培养含CK的培养基上没有事先生长的CIM。因此，看来木质部周壁比以前认为的多能性更强。这种多能性伴随着即使在几轮细胞分裂后，膜衍生物仍能保持二倍体的能力。与此相反，韧皮部周壁没有表现出这样的发育可塑性，并回应CK只有平周分裂。这些观察结果加强了这样的观点，即周鞘是一个“延伸的分生组织”，包括两种类型的细胞群。他们还表明，LRM启动的创始细胞最初并没有完全指定为这一发育途径。
We have established a detailed framework for the process of shoot regeneration from Arabidopsis root and hypocotyl explants grown in vitro. Using transgenic plant lines in which the GUS or GFP genes were fused to promoters of developmental genes (WUS, CLV1, CLV3, STM, CUC1, PLT1, RCH1, QC25), or to promoters of genes encoding indicators of the auxin response (DR5) or transport (PIN1), cytokinin (CK) response (ARR5) or synthesis (IPT5), or mitotic activity (CYCB1), we showed that regenerated shoots originated directly or indirectly from the pericycle cells adjacent to xylem poles. In addition, shoot regeneration appeared to be partly similar to the formation of lateral root meristems (LRMs). During pre-culture on a 2, 4-dichlorophenoxyacetic acid (2, 4-D)-rich callus-inducing medium (CIM), xylem pericycle reactivation established outgrowths that were not true calli but had many characteristics of LRMs. Transfer to a CK-rich shoot-inducing medium (SIM) resulted in early LRM-like primordia changing to shoot meristems. Direct origin of shoots from the xylem pericycle occurred upon direct culture on CK-containing media without prior growth on CIM. Thus, it appeared that the xylem pericycle is more pluripotent than previously thought. This pluripotency was accompanied by the ability of pericycle derivatives to retain diploidy, even after several rounds of cell division. In contrast, the phloem pericycle did not display such developmental plasticity, and responded to CKs with only periclinal divisions. Such observations reinforce the view that the pericycle is an 'extended meristem' that comprises two types of cell populations. They also suggest that the founder cells for LRM initiation are not initially fully specified for this developmental pathway.