Auxin and root initiation in somatic embryos of Arabidopsis
Auxin and root initiation in somatic embryos of Arabidopsis
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DOI：
10.1007/s00299-006-0207-5
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发表时间：
2007-01-01
影响因子：
6.2
通讯作者：
Yeung, Edward C.
中科院分区：
文献类型：
--
作者：
Bassuner, Burgund M.;Lam, Russell;Yeung, Edward C.
拟南芥的体细胞胚可以从发育中的合子胚的外植体产生。外植体在成熟培养基上的培养导致三种主要类型的再生结构的发育：不定芽、融合芽和完整的体细胞胚。使用连续塑料切片检查这些结构的个体发育和解剖。此外，两个分子标记进行了测定，以监测转录生长素的反应和根分生组织的形成在这个过程中：PIN 4的LENNY等位基因，一个转座子插入创建一个融合的报告基因GUS;和DR 5：：GUS，生长素诱导的转录的合成报告。在合子胚胎发生中，PIN 4表达局限于根分生组织的中心，并开始在胚胎发生的球形阶段检测到，而DR 5：：GUS表达在根的更远侧区域标记“生长素感知最大值”。不定芽和融合的芽没有解剖学上可识别的根分生组织，并且在其基端不表达两个标记中的任何一个。相反，其轴的脉管系统直接连接到外植体的脉管系统。相比之下，完整的体细胞胚仅松散地附着在外植体上，具有解剖学上定义的根分生组织，并且在其根端显示两个标记的表达。我们的研究结果表明，根分生组织在体细胞胚的建立需要适当的生长素水平在其发展过程中。
Somatic embryos of Arabidopsis thaliana can be produced from explants of developing zygotic embryos. Cultivation of explants on maturation medium results in development of three main classes of regenerative structures: adventitious shoots, fused shoots, and complete somatic embryos. The ontogeny and anatomy of these structures was examined using serial plastic sections. Furthermore, two molecular markers were assayed to monitor transcriptional auxin responses and formation of a root meristem in this process: the LENNY allele of PIN4, a transposon insertion creating a fusion to the reporter gene GUS; and DR5::GUS, a synthetic reporter of auxin-induced transcription. In zygotic embryogenesis, PIN4 expression is confined to the center of the root meristem and begins to be detectable by the globular stage of embryogenesis, while DR5::GUS expression marks an "auxin perception maximum" in the more distal regions of the root. Adventitious and fused shoots develop no anatomically recognizable root meristem and do not express either of the two markers at their basal pole. Instead, the vasculature of their axis is directly connected to the vasculature of the explant. By contrast, complete somatic embryos were only loosely attached to the explant, had an anatomically defined root meristem and showed expression of both markers at their root pole. Our results suggest that the establishment of a root meristem in somatic embryos required appropriate auxin levels during the course of their development.