Kinnersley A M, Davies P J
Section of Genetics, Development and Physiology, Division of Biological Sciences, Cornell University, Ithaca, New York 14853.
Plant Physiol. 1976 Dec;58(6):777-82. doi: 10.1104/pp.58.6.777.
Anthocyanin synthesis, hair formation, and the synthesis of ascorbic acid oxidase are all phytochrome-mediated reactions occurring in the hypocotyl of mustard (Sinapis alba L.), controlled by phytochrome actually located in the hypocotyl. A comparison of these three reactions showed that in certain respects they differ greatly in their response to light. The ability of the seedling to respond to light by showing the three responses was strongly influenced by the state of development of the seedling. White light given very early after seed imbibition was unable to evoke any of the three reactions. By 50 hours after imbibition, all systems were fully inducible by light. The addition of actinomycin D to a fully competent seedling coincident with illumination strongly inhibited the development of all three responses. In contrast, the addition of cordycepin at this time inhibited the synthesis of anthocyanin and ascorbic acid oxidase but had no effect on hair formation. Cycloheximide inhibited all three responses when given up to several hours after light. This suggests the necessity for RNA and protein synthesis for light-induced expression of these reactions, and that the RNA species involved in the three reactions may have differing degrees of polyadenylation. The lag period between the onset of light and the first display of the response was 3 hours for anthocyanin and ascorbic acid oxidase synthesis, and about 5 hours for hair formation. Amounts of light sufficient to give large increases in the levels of ascorbic acid oxidase and hair formation gave a much smaller increase in anthocyanin synthesis. Hair formation and ascorbic acid oxidase synthesis showed a much greater sensitivity to induction at early stages of seedling development than did anthocyanin synthesis. Following an inductive light period, anthocyanin synthesis was sensitive to far red light inhibition for a period twice as long as the other two reactions. The differences in the response of the three reactions to light suggest that the phytochrome-mediated reactions which control their development also differ.
花青素合成、毛发形成以及抗坏血酸氧化酶的合成都是由光敏色素介导的反应，发生在芥菜（白芥）的下胚轴中，实际上由位于下胚轴中的光敏色素控制。对这三种反应的比较表明，在某些方面它们对光的反应差异很大。幼苗通过表现出这三种反应来对光作出反应的能力受到幼苗发育状态的强烈影响。种子吸胀后很早给予的白光无法引发这三种反应中的任何一种。吸胀后50小时，所有系统都完全可被光诱导。在光照时向完全有反应能力的幼苗中添加放线菌素D强烈抑制了所有三种反应的发展。相比之下，此时添加虫草素抑制了花青素和抗坏血酸氧化酶的合成，但对毛发形成没有影响。放线菌酮在光照后数小时内给予时抑制了所有三种反应。这表明这些反应由光诱导表达需要RNA和蛋白质合成，并且参与这三种反应的RNA种类可能具有不同程度的聚腺苷酸化。光照开始与反应首次出现之间的延迟期，花青素和抗坏血酸氧化酶合成是3小时，毛发形成约为5小时。足以使抗坏血酸氧化酶水平和毛发形成大幅增加的光量，使花青素合成的增加幅度小得多。毛发形成和抗坏血酸氧化酶合成在幼苗发育早期对诱导的敏感性比花青素合成高得多。在诱导光照期之后，花青素合成对远红光抑制的敏感时期是其他两种反应的两倍。这三种反应对光的反应差异表明，控制它们发育的光敏色素介导的反应也不同。
