Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.
Plant Biotechnol J. 2018 Feb;16(2):451-458. doi: 10.1111/pbi.12784. Epub 2017 Jul 27.
Tissue-specific overexpression of useful genes, which we can design according to their cause-and-effect relationships, often gives valuable gain-of-function phenotypes. To develop genetic tools in woody biomass engineering, we produced a collection of Arabidopsis lines that possess chimeric genes of a promoter of an early xylem differentiation stage-specific gene, Arabidopsis Tracheary Element Differentiation-related 4 (AtTED4) and late xylem development-associated genes, many of which are uncharacterized. The AtTED4 promoter directed the expected expression of transgenes in developing vascular tissues from young to mature stage. Of T2 lines examined, 42%, 49% and 9% were judged as lines with the nonrepeat type insertion, the simple repeat type insertion and the other repeat type insertion of transgenes. In 174 T3 lines, overexpression lines were confirmed for 37 genes, whereas only cosuppression lines were produced for eight genes. The AtTED4 promoter activity was high enough to overexpress a wide range of genes over wild-type expression levels, even though the wild-type expression is much higher than AtTED4 expression for several genes. As a typical example, we investigated phenotypes of pAtTED4::At5g60490 plants, in which both overexpression and cosuppression lines were included. Overexpression but not cosuppression lines showed accelerated xylem development, suggesting the positive role of At5g60490 in xylem development. Taken together, this study provides valuable results about behaviours of various genes expressed under an early xylem-specific promoter and about usefulness of their lines as genetic tools in woody biomass engineering.
组织特异性过表达有用的基因，我们可以根据它们的因果关系进行设计，这通常会产生有价值的功能获得表型。为了在木质生物质工程中开发遗传工具，我们生产了一系列拟南芥株系，这些株系拥有早期木质部分化阶段特异性基因拟南芥 Tracheary Element Differentiation-related 4（AtTED4）和晚期木质部发育相关基因的嵌合基因，其中许多基因尚未被描述。AtTED4 启动子指导转基因在从幼嫩到成熟阶段的发育血管组织中的预期表达。在所检查的 T2 株系中，42%、49%和 9%被判定为具有转基因非重复型插入、简单重复型插入和其他重复型插入的株系。在 174 个 T3 株系中，有 37 个基因被确认为过表达株系，而只有 8 个基因产生了共抑制株系。AtTED4 启动子活性足够高，可以在野生型表达水平上过表达广泛的基因，尽管对于几个基因来说，野生型表达比 AtTED4 表达高得多。作为一个典型的例子，我们研究了 pAtTED4::At5g60490 植物的表型，其中包括过表达和共抑制株系。过表达但不共抑制的株系表现出加速的木质部发育，表明 At5g60490 在木质部发育中具有积极作用。总之，这项研究提供了关于在早期木质部特异性启动子下表达的各种基因的行为以及它们的株系作为木质生物质工程遗传工具的有用性的有价值的结果。
