Sumitomo Katsuhiko, Narumi Takako, Satoh Shigeru, Hisamatsu Tamotsu
National Institute of Floricultural Science (NIFS), National Agriculture and Food Research Organization (NARO), 2-1 Fujimoto, Tsukuba, Ibaraki 305-8519, Japan.
J Exp Bot. 2008;59(15):4075-82. doi: 10.1093/jxb/ern247. Epub 2008 Oct 24.
Temperature plays a significant role in the annual cycling between growth and dormancy of the herbaceous perennial chrysanthemum (Chrysanthemum morifolium Ramat.). After exposure to high summer temperatures, cool temperature triggers dormancy. The cessation of flowering and rosette formation by the cessation of elongation are characteristic of dormant plants, and can be stimulated by exogenous ethylene. Thus, the ethylene response pathway may be involved in temperature-induced dormancy of chrysanthemum. Transgenic chrysanthemums expressing a mutated ethylene receptor gene were used to assess this involvement. The transgenic lines showed reduced ethylene sensitivity: ethylene causes leaf yellowing in wild-type chrysanthemums, but leaves remained green in the transgenic lines. Extension growth and flowering of wild-type and transgenic lines varied between temperatures: at 20 degrees C, the transgenic lines showed the same stem elongation and flowering as the wild type; at cooler temperatures, the wild type formed rosettes with an inability to flower and entered dormancy, but some transgenic lines continued to elongate and flower. This supports the involvement of the ethylene response pathway in the temperature-induced dormancy of chrysanthemum. At the highest dosage of ethephon, an ethylene-releasing agent, wild-type plants formed rosettes with an inability to flower and became dormant, but one transgenic line did not. This confirms that dormancy is induced via the ethylene response pathway.
温度在多年生草本菊花（Chrysanthemum morifolium Ramat.）生长与休眠的年度循环中起着重要作用。在经历夏季高温后，凉爽的温度会触发休眠。开花停止以及莲座状形成（通过伸长停止）是休眠植物的特征，并且可被外源乙烯诱导。因此，乙烯反应途径可能参与了温度诱导的菊花休眠。利用表达突变乙烯受体基因的转基因菊花来评估这种参与情况。转基因株系表现出乙烯敏感性降低：乙烯会使野生型菊花叶片变黄，但转基因株系的叶片仍保持绿色。野生型和转基因株系的伸长生长和开花在不同温度下有所不同：在20摄氏度时，转基因株系与野生型表现出相同的茎伸长和开花情况；在较低温度下，野生型形成莲座状且无法开花并进入休眠，但一些转基因株系继续伸长和开花。这支持了乙烯反应途径参与温度诱导的菊花休眠。在乙烯释放剂乙烯利的最高剂量下，野生型植物形成莲座状且无法开花并进入休眠，但一个转基因株系没有。这证实休眠是通过乙烯反应途径诱导的。
