Larsson Emma, Sitbon Folke, Ljung Karin, Von Arnold Sara
Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, PO Box 7080, SE-75007 Uppsala, Sweden.
Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden.
New Phytol. 2008;177(2):356-366. doi: 10.1111/j.1469-8137.2007.02289.x. Epub 2007 Nov 27.
Current hypotheses concerning the role of polar auxin transport in embryo development are entirely based on studies of angiosperms, while little is known about how auxin regulates pattern formation in gymnosperms. In this study, different developmental stages of somatic embryos of Norway spruce (Picea abies) were treated with the polar auxin transport inhibitor 1-N-naphtylphthalamic acid (NPA). Effects of the treatments on auxin content, embryo differentiation and programmed cell death (PCD) were analysed. During early embryo development, NPA-treatment led to increased indole-3-acetic acid (IAA) content, abnormal cell divisions and decreased PCD, resulting in aberrant development of embryonal tube cells and suspensors. Mature embryos that had been treated with NPA showed both apical and basal abnormalities. Typically the embryos had abnormal cotyledon formation and irregular cell divisions in the area of the root meristem. Our results show that polar auxin transport is essential for the correct patterning of both apical and basal parts of conifer embryos throughout the whole developmental process. Furthermore, the aberrant morhologies of NPA-treated spruce embryos are comparable with several auxin response and transport mutants in Arabidopsis. This suggests that the role of polar auxin transport is conserved between angiosperms and gymnosperms.
目前关于极性生长素运输在胚胎发育中作用的假说完全基于被子植物的研究，而对于生长素如何调控裸子植物的模式形成却知之甚少。在本研究中，用极性生长素运输抑制剂1-N-萘基邻苯二甲酸（NPA）处理挪威云杉（Picea abies）体细胞胚胎的不同发育阶段。分析了处理对生长素含量、胚胎分化和程序性细胞死亡（PCD）的影响。在胚胎发育早期，NPA处理导致吲哚-3-乙酸（IAA）含量增加、细胞分裂异常以及PCD减少，从而导致胚管细胞和胚柄发育异常。用NPA处理的成熟胚胎表现出顶端和基部均异常。典型的情况是，胚胎子叶形成异常，根分生组织区域细胞分裂不规则。我们的结果表明，极性生长素运输对于整个发育过程中针叶树胚胎顶端和基部的正确模式形成至关重要。此外，NPA处理的云杉胚胎的异常形态与拟南芥中的几种生长素响应和运输突变体相当。这表明极性生长素运输的作用在被子植物和裸子植物之间是保守的。
