Differential regulation of anthocyanin pigmentation by temperature in Cymbidium orchid flowers

与其他植物一样，兰花的花瓣和花被片中花青素的积累也受到低温的刺激。另一方面，唇部的这种作用不是由低温促进的，而是由高温促进的。以红宝石眼‘金星’、花冠‘Haru-no-umi’和谷花‘Three Lip M_rchen’3个兰花品种为材料，研究了花色苷着色随温度的变化规律。在高温处理初期(31ﾟC光/23ﾟC暗温度，16h光周期)，不同花蕾发育阶段的唇瓣着色模式不同。在幼嫩花蕾中，高温强烈刺激唇瓣色素沉着。高温处理3d后，花青素在唇瓣中的积累不可逆。高温的影响随着花芽的发育而减弱。高温对发育良好的花蕾唇瓣中花青素的积累影响很小或没有影响。在谷花‘三唇’花的两个唇瓣状花瓣中，高温促进了花青素的着色，与真唇瓣一样。高温诱导的兰花唇瓣花色苷着色似乎不同于授粉和/或去雄诱导的唇瓣着色，花青素生物合成途径的步骤(S)受温度的不同调控仍有待确定。

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.