McCombs P J, Ralph R K
Biochem J. 1972 Sep;129(2):403-17. doi: 10.1042/bj1290403.
Bacteria-free cultures of Spirodela oligorrhiza continue to increase in frond number for 2 to 3 days after transfer to darkness. There is then no further increase in frond number for 3 to 4 weeks, although DNA, RNA and protein synthesis continue at decreased rates and starch accumulates in the plants. We refer to such ;non-growing' plants in darkness as dormant. Adding kinetin to dormant Spirodela initiated increased DNA, RNA and protein synthesis within 1h, although new fronds were not detected until 24h after the addition of kinetin. The frond number then continued to increase. Starch accumulated in dormant plants. Accumulation of starch appeared to be a consequence of inhibition of growth rather than the converse. No evidence was obtained for a block in [(14)C]glucose metabolism that might explain the lack of growth in darkness in the absence of kinetin. In darkness, more ribosomes were membrane-bound in dormant Spirodela than in Spirodela growing with kinetin. Similarities between the response of Spirodela to darkness, stringent control in bacteria and pleiotypic controls in animal cells are discussed. It is suggested that all three processes are ultimately controlled by specific protein kinases that are individually sensitive to different effectors.
少根紫萍的无菌培养物在转移至黑暗环境后，叶状体数量会持续增加2至3天。此后3至4周内，叶状体数量不再增加，尽管DNA、RNA和蛋白质合成仍以降低的速率继续进行，且淀粉在植物体内积累。我们将黑暗中这种“不生长”的植物称为休眠植物。向休眠的少根紫萍添加激动素后，1小时内DNA、RNA和蛋白质合成开始增加，不过直到添加激动素24小时后才检测到新的叶状体。此后叶状体数量继续增加。淀粉在休眠植物中积累。淀粉的积累似乎是生长受抑制的结果，而非相反。未获得证据表明存在对[(14)C]葡萄糖代谢的阻断，这可能解释在没有激动素的情况下黑暗中生长停滞的现象。在黑暗中，休眠少根紫萍中膜结合核糖体比在添加激动素生长的少根紫萍中更多。文中讨论了少根紫萍对黑暗的反应、细菌中的严紧控制和动物细胞中的多效控制之间的相似性。有人提出，所有这三个过程最终都由对不同效应物分别敏感的特定蛋白激酶控制。
