Kang Julie, Tang John, Donnelly Petra, Dengler Nancy
Department of Botany, University of Toronto, Toronto, Ontario, M5S 1A1, Canada.
New Phytol. 2003 Jun;158(3):443-454. doi: 10.1046/j.1469-8137.2003.00769.x.
• Primary vascular pattern determines pathways of long distance transport for water, nutrients and signalling molecules within plant shoot systems. • Expression of an Arabidopsis thaliana homeobox gene 8::GUS construct is restricted to the procambium and provides a molecular marker for vascular pattern at early developmental stages. • Primary vascular pattern and phyllotaxis are highly coordinated, with vascular sympodia corresponding to phyllotactic parastichies. During vegetative development, primary vasculature forms a reticulate pattern, with each leaf trace derived from two vascular sympodia. Shoot phase change is marked by alterations of this fundamental pattern. Formation of leaf trace procambial strands is temporally coordinated with primordium initiation, but ATHB-8::GUS expression is discontinuous in these strands at early stages. • The interconnection of vascular sympodia provides alternate pathways for long distance transport in shoots of A. thaliana and reflects the limited secondary growth in this species. ATHB-8::GUS expression identifies a prepattern that precedes anatomical definition of procambium. The longitudinal discontinuity in ATHB-8::GUS expression indicates that one function of this gene is to define the xylem components of vascular radial pattern.
• 初生维管模式决定了植物地上部系统中水分、养分和信号分子的长距离运输途径。
• 拟南芥同源异型框基因8::GUS构建体的表达局限于原形成层，为早期发育阶段的维管模式提供了一个分子标记。
• 初生维管模式和叶序高度协调，维管合轴单位对应于叶序斜列线。在营养生长发育过程中，初生维管系统形成网状模式，每个叶迹源自两个维管合轴单位。地上部阶段变化以这种基本模式的改变为标志。叶迹原形成层束的形成在时间上与原基起始协调一致，但在早期这些束中ATHB - 8::GUS的表达是不连续的。
• 维管合轴单位的相互连接为拟南芥地上部的长距离运输提供了替代途径，并反映了该物种有限的次生生长。ATHB - 8::GUS表达确定了在原形成层解剖学定义之前的一种预模式。ATHB - 8::GUS表达中的纵向不连续性表明该基因的一个功能是定义维管径向模式的木质部成分。
