MOLECULAR ANALYSIS OF PLANT ORGAN AND TISSUE DEVELOPMENT

本研究分为两个项目。我从拟南芥中分离出cuc突变体，该突变体的幼苗有融合的子叶，但没有茎尖分生组织。该突变体是由CUCI和CUC2基因双突变引起的，并克隆了CUC2基因。在本研究中，我们明确了以下四点。(1) CUC基因是茎尖分生组织形成过程中STM表达起始的重要基因。(2)后期CUC2在空间上适当表达以分离子叶需要STM。(3) CUC2在茎尖分生组织与叶原基、花序分生组织与花分生组织、花各器官之间表达。(4) ccu是形成完整雌蕊和胚珠所必需的。茎部倾斜；茎部呈负向重力。为了研究芽向地性的分子机制，我们从拟南芥中分离了许多减少向地性的突变体，并鉴定出9个与芽向地性有关的新位点SGRl-7、RHG和SLR。在本研究中，我们明确了以下四点。(1)编码bZIP型转录因子的sgr1和SGR7对下胚轴和花序干的内胚层细胞分化至关重要，内胚层细胞是这些器官的重力感知细胞。(2) SLR基因编码JAA 14基因，该基因是生长素信号通路中重要的核蛋白。(3) SGR2在茎向地向性和胚胎发生中都起重要作用。(4) sgr4在下胚轴和花序茎的内胚层细胞中淀粉质体定位和运动异常，导致向地性减弱。

This research is divided into two projects.1. Organ separation and shoot meristem formation I have isolated the cuc mutant in Arabidopsis thaliana, which seedlings have fused cotyledons and no shoot apical meristem. This mutant was caused by double mutations in CUCI and CUC2 genes and CUC2 genes was cloned. In this research, we made clear next 4 points. (1) The CUC genes were essential for initiation of STM expression to form shoot apical meristem. (2) STM was required for proper spatial expression of CUC2 at later stages to separate cotyledons. (3) CUC2 was expressed at boundaries between shoot apical meristem and leaf primordia, between inflorescence meristem and floral meristem, and among each organs of flowers. (4) CUCs were essential to form intact gynoecium and ovules in flowers.2. Shoot gravitropism ; Shoot shows negative gravitropism. To investigate molecular mechanisms of shoot gravitropism, we have isolated many reduced-gravitropic mutants from Arabidopsis thaliana and identified 9 new loci relating to shoot gravitropism, SGRl-7, RHG and SLR.In this research, we made clear next 4 points. (1) The SGRl, which encodes bZIP type transcription factor, and SGR7 were essential for endoderm cell differentiation in hypocotyl and inflorescence stem and endoderm cells were gravity perception cells in these organs. (2) The SLR gene encodes JAA 14 gene, which was a nuclear protein and important in auxin signaling pathway. (3) SGR2 was important for both shoot gravitropism and embryogenesis. (4) sgr4 was abnormal in amyloplastlocalization and movement in endoderm cells of hypocotyl and inflorescence stems causing reduced gravitropism.