A RING domain gene is expressed in different cell types of leaf trace, stem, and juvenile bundles in the stem vascular system of zinnia
A RING domain gene is expressed in different cell types of leaf trace, stem, and juvenile bundles in the stem vascular system of zinnia
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DOI：
10.1104/pp.104.057901
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发表时间：
2005-07-01
期刊：
影响因子：
7.4
通讯作者：
McCann, MC
中科院分区：
文献类型：
--
作者：
Dahiya, P;Milioni, D;McCann, MC
体外百日草（Zinnia elegans）叶肉细胞系统，其中叶片叶肉细胞被诱导高度同步地转分化为气管元件，已成为研究木质发生的既定模型。百日草 Envy 的茎维管系统的结构包含三个处于不同发育阶段的解剖学上不同的维管束。顶端下区域的幼年维管束发育成具有叶迹段和茎段的成熟维管束。幼虫、叶迹和茎束中基因表达的特征模式通过分子标记、RING 结构域编码基因 ZeRH2.1 来揭示，ZeRH2.1 最初是从源自分化体外培养物的百日草 cDNA 文库中分离出来的。通过 RNA 原位杂交，我们发现 ZeRH2.1 在成熟百日草茎中的两种特定细胞类型中优先表达。在叶迹束中，ZeRH2.1 转录物在木质部薄壁细胞中丰富，而在茎束中，它在韧皮部伴细胞中丰富。这两种细胞类型均表现出转移细胞的壁向内生长特征。此外，ZeRH2.1转录本在幼年束的一些韧皮部细胞和叶栅栏薄壁组织中丰富。 ZeRH2.1 复杂且受发育调节的表达模式揭示了百日草茎血管解剖结构的异质性。我们讨论了该基因在细胞间运输过程中的潜在功能。
The in vitro zinnia ( Zinnia elegans) mesophyll cell system, in which leaf mesophyll cells are induced to transdifferentiate into tracheary elements with high synchrony, has become an established model for studying xylogenesis. The architecture of the stem vascular system of zinnia cv Envy contains three anatomically distinct vascular bundles at different stages of development. Juvenile vascular strands of the subapical region develop into mature vascular strands with leaf trace segments and stem segments. Characteristic patterns of gene expression in juvenile, leaf trace, and stem bundles are revealed by a molecular marker, a RING domain-encoding gene, ZeRH2.1, originally isolated from a zinnia cDNA library derived from differentiating in vitro cultures. Using RNA in situ hybridization, we show that ZeRH2.1 is expressed preferentially in two specific cell types in mature zinnia stems. In leaf trace bundles, ZeRH2.1 transcript is abundant in xylem parenchyma cells, while in stem bundles it is abundant in phloem companion cells. Both of these cell types show wall ingrowths characteristic of transfer cells. In addition, ZeRH2.1 transcript is abundant in some phloem cells of juvenile bundles and in leaf palisade parenchyma. The complex and developmentally regulated expression pattern of ZeRH2.1 reveals heterogeneity in the vascular anatomy of the zinnia stem. We discuss a potential function for this gene in intercellular transport processes.