Differential regulation of anthocyanin pigmentation by temperature in Cymbidium orchid flowers

与其他植物一样，低温也能促进大花蕙兰花瓣和萼片中花青素的积累。另一方面，唇瓣中的酶不受低温的促进，而受高温的促进。以3个大花蕙兰品种（红宝石眼'金星'、Sazanami '春之海'和山谷花'三唇M_rchen'）为材料，研究了不同温度（31 ℃光照/23 ℃黑暗，16 h光周期）处理下，花色素苷色素的变化规律。在年轻的花蕾，唇瓣色素沉着强烈刺激高温。即使在高温处理3天后，唇瓣中花色苷的积累也是不可逆的。随着花芽的发育，高温的影响逐渐减弱。高温对发育良好的花蕾唇瓣花色素苷的积累几乎没有影响。另外，在谷花“三唇M_rchen”花的两个唇瓣状花瓣中，与真唇瓣一样，高温促进了花色素苷的着色。高温诱导的大花蕙兰唇瓣花色素苷合成与授粉和/或去雄诱导的唇瓣花色素苷合成是不同的现象，温度对唇瓣花色素苷合成的调控与其它花被花色素苷合成的调控不同。

As in other plants, anthocyanin accumulation in the petals and sepals of Cymbidium flowers is also stimulated by low temperature. On the other hand, that in the labellum is promoted not by low temperature but by high temperature. This interesting differential regulatory mechanism of anthocyanin pigmentation by temperature was investigated with three Cymbidium hybrids (Ruby Eyes 'Golden Star', Sazanami 'Haru-no-umi', Valley Flower 'Three Lip M_rchen'.Pigmentation pattern of the labellum at anthesis varied with developmental stages of flower buds at the onset of high temperature treatment (31ﾟC light/23ﾟC dark temperatures, 16 h photoperiod). In younger flower buds, labellum pigmentation was strongly stimulated by high temperature. Anthocyanin accumulation in the labellum was induced irreversively even by high temperatue for only 3 days. The influence of high temperature decreased with flower bud development. High temperature had little or no effect on the anthocyanin accumulation in the labellum of well-developed flower buds. Also in the two labellum-like petals of Valley Flower 'Three Lip M_rchen' flowers, anthocyanin pigmentation was promoted by high temperature as in the true labellum. The high temperature-induced stimulation of anthocyanin pigmentation in the labellum of Cymbidium hybrids seems to be a different phenomenon from pollination- and/or emasculation-induced labellum coloration.The step(s) of the anthocyanin biosynthetic pathway which is differentially regulated between the labellum and the other perianths by temperature remains to be determined.