Werner T, Motyka V, Strnad M, Schmülling T
Centre for Plant Molecular Biology (ZMBP)/Allgemeine Genetik, Universität Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany.
Proc Natl Acad Sci U S A. 2001 Aug 28;98(18):10487-92. doi: 10.1073/pnas.171304098. Epub 2001 Aug 14.
Cytokinins are a class of plant-specific hormones that play a central role during the cell cycle and influence numerous developmental programs. Because of the lack of biosynthetic and signaling mutants, the regulatory roles of cytokinins are not well understood. We genetically engineered cytokinin oxidase expression in transgenic tobacco plants to reduce their endogenous cytokinin content. Cytokinin-deficient plants developed stunted shoots with smaller apical meristems. The plastochrone was prolonged, and leaf cell production was only 3-4% that of wild type, indicating an absolute requirement of cytokinins for leaf growth. In contrast, root meristems of transgenic plants were enlarged and gave rise to faster growing and more branched roots. These results suggest that cytokinins are an important regulatory factor of plant meristem activity and morphogenesis, with opposing roles in shoots and roots.
细胞分裂素是一类植物特有的激素，在细胞周期中起核心作用，并影响众多发育程序。由于缺乏生物合成和信号转导突变体，细胞分裂素的调控作用尚未得到充分理解。我们通过基因工程在转基因烟草植株中表达细胞分裂素氧化酶，以降低其内源细胞分裂素含量。细胞分裂素缺乏的植株茎尖发育受阻，顶端分生组织较小。节间延长，叶片细胞产量仅为野生型的3-4%，表明叶片生长绝对需要细胞分裂素。相反，转基因植株的根分生组织增大，产生生长更快、分支更多的根。这些结果表明，细胞分裂素是植物分生组织活性和形态发生的重要调节因子，在茎和根中发挥相反的作用。
