State Key Laboratory of Tree Genetics and Breeding; Research Institute of Forestry, Chinese Academy of Forestry, 100091, Beijing, China.
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, 510650, Guangzhou, China.
Commun Biol. 2020 Feb 28;3(1):89. doi: 10.1038/s42003-020-0821-8.
An unbalanced pigment distribution among the sepal and petal segments results in various colour patterns of orchid flowers. Here, we explored this type of mechanism of colour pattern formation in flowers of the Cattleya hybrid 'KOVA'. Our study showed that pigment accumulation displayed obvious spatiotemporal specificity in the flowers and was likely regulated by three R2R3-MYB transcription factors. Before flowering, RcPAP1 was specifically expressed in the epichile to activate the anthocyanin biosynthesis pathway, which caused substantial cyanin accumulation and resulted in a purple-red colour. After flowering, the expression of RcPAP2 resulted in a low level of cyanin accumulation in the perianths and a pale pink colour, whereas RcPCP1 was expressed only in the hypochile, where it promoted α-carotene and lutein accumulation and resulted in a yellow colour. Additionally, we propose that the spatiotemporal expression of different combinations of AP3- and AGL6-like genes might participate in KOVA flower colour pattern formation.
花瓣和萼片之间色素分布不均导致兰花花朵呈现出各种颜色图案。在这里，我们探索了卡特兰杂种 'KOVA' 花朵中这种颜色图案形成的机制。我们的研究表明，色素积累在花朵中表现出明显的时空特异性，可能受到三个 R2R3-MYB 转录因子的调节。在开花前，RcPAP1 特异性表达在上唇表皮细胞中，激活花色素生物合成途径，导致大量飞燕草色素积累，呈现出紫红色。开花后，RcPAP2 的表达导致花被片积累低水平的飞燕草色素，呈现出浅粉色，而 RcPCP1 仅在下唇表皮细胞中表达，促进α-胡萝卜素和叶黄素的积累，呈现出黄色。此外，我们提出不同组合的 AP3-和 AGL6 样基因的时空表达可能参与了 KOVA 花朵颜色图案的形成。
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