Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan; College of Agriculture, Academic Institute, Shizuoka University, Shizuoka, 422-8529, Japan.
Research Institute of Green Science and Technology, Shizuoka University, Shizuoka, 422-8529, Japan; Center for Bioscience Research and Education, Utsunomiya University, Utsunomiya, 321-8508, Japan.
Plant Sci. 2019 Oct;287:110173. doi: 10.1016/j.plantsci.2019.110173. Epub 2019 Jun 24.
Anthocyanins are responsible for red, purple, and pink pigmentation of flowers in Cymbidium hybrids. Although anthocyanin content in all floral organs increases with flower development, they increase markedly in the tepals compared with the labella or columns. Using next-generation sequencing technology, we identified three anthocyanin biosynthesis regulatory genes, CyMYB1, CybHLH1, and CybHLH2, from Cymbidium 'Mystique'. Yeast two-hybrid analysis showed that the CyMYB1 protein can form a heterodimer with either CybHLH1 or CybHLH2. In the tepals, the expression level of CyMYB1 increased as the flower developed, whereas the high expression level of CyMYB1 was detected at the early flower developmental stages in the labella and columns, remaining constant until increasing at the late developmental stage. These expression profiles of CyMYB1 positively correlated with the profiles of anthocyanin accumulation in the tepals. When Cymbidium Sazanami 'Champion' was grown at 30 °C/25 °C, reduced anthocyanin levels were observed, specifically in the tepals, compared with those in flowers grown at 20 °C/15 °C. The transcription of CyMYB1 in the tepals was suppressed at high temperatures, and the expressions of CyDFR and CyANS were also synchronously suppressed. This study revealed that CyMYB1 activates the transcription of CyDFR and CyANS and regulates the temporal- and temperature-dependent anthocyanin accumulation in Cymbidium tepals.
花色素苷是导致蝴蝶兰杂交品种花朵呈现红色、紫色和粉色的原因。尽管所有花器官的花色素苷含量随着花朵的发育而增加，但在萼片和花瓣或柱头中，花色素苷含量显著增加。使用下一代测序技术，我们从蝴蝶兰 'Mystique' 中鉴定出三个花色素苷生物合成调控基因 CyMYB1、CybHLH1 和 CybHLH2。酵母双杂交分析表明，CyMYB1 蛋白可以与 CybHLH1 或 CybHLH2 形成异源二聚体。在萼片中，CyMYB1 的表达水平随着花朵的发育而增加，而在花瓣和柱头中，CyMYB1 的高表达水平则出现在早期的花朵发育阶段，一直保持不变，直到晚期发育阶段才增加。这些 CyMYB1 的表达谱与萼片中花色素苷积累的谱呈正相关。当蝴蝶兰 'Champion' 在 30°C/25°C 下生长时，与在 20°C/15°C 下生长的花朵相比，萼片中的花色素苷水平明显降低。萼片中 CyMYB1 的转录在高温下受到抑制，同时 CyDFR 和 CyANS 的表达也受到同步抑制。本研究表明，CyMYB1 激活 CyDFR 和 CyANS 的转录，并调节蝴蝶兰花萼片中时间和温度依赖的花色素苷积累。
