Flower color, one of the most important quality traits for ornamental plants, is of great adaptive significance during the natural evolution process of plants. Moreover, flower color is also an important content for epigenetic researches. Anthocyanins, the most important pigments for flower coloration, designate the flower colors of approximately 80% plant families in angiosperm. Up to date, more than 600 anthocyanins have been isolated and identified from the natural world, which are mainly derived from six anthocyanidins. The biosynthetic pathway of anthocyanins has been well studied, which starts from the flavonoid metabolic pathway. Different branch pathways result in the diversity of anthocyanins, mainly due to the differences of substituent groups that are located on the basic skeleton of various anthocyanidins. During the biosynthetic process of anthocyanins, the competition forces of enzymes which are located on the branch nodes and the substrate specificity of some key enzymes result in the genus and species specificity of anthocyanins and the corresponding flower color phenotypes. Anthocyanins are transferred to vacuole and are packaged as chromatophore after being biosynthesized. The accumulation and conserve abilities on the chromatophore of vacuole affect the coloration of anthocyanins to a large extent. Therefore, many intracellular factors, such as the pH value of vacuole, the content of co-pigments and the complexation of metal ion, jointly affect the final coloration of anthocyanins in the petals. At present, some structural and regulatory genes that are related to the anthocyanins biosynthesis and coloration have been isolated, whose functions also have been well revealed. Based on these genes, some transgenic flowers have been successfully bred out. However, the mechanisms of gene regulating expression, including the regulation mechanisms on the transcriptional and post-transcriptional levels, and the differences of DNA sequences and the DNA methylation, still remain elusive. Moreover, the present modifications on the flower colors are still very limited. Therefore, how to apply these mechanisms on the transgenic breeding of flower color modification is a frontier topic. Revealing the organ coloration mechanisms based on anthocyanins in horticultural crops is conducive to the understanding of coloration mechanisms of flowers; studies on the mechanisms of flower color in ornamental plants is of important reference value for the reveal of the organ coloration mechanisms in horticultural crops. Therefore, in this paper, we reviewed the mechanisms of flower coloration in ornamental plants from three aspects, including the mechanisms of the branch pathways generation, the genetic regulation mechanisms of anthocyanins biosynthetic pathway, and the main factors affecting the anthocyanins coloration and the corresponding genetic regulation mechanisms. Finally, we summarized the successes of molecular design breeding on flower color modification based on these mechanisms, especially the international-concerned molecular breeding for blue flowers, aiming at providing references for the directive breeding of ornamental plants with novel flower colors.%花色是观赏植物最重要的品质性状之一，是植物自然进化过程中最具适应意义的表型性状，也是表观遗传学研究的重要内容。花青素苷是使花朵呈色的重要色素之一，被子植物中约有80%的科的花朵颜色由花青素苷决定；迄今从自然界分离和鉴定出的花青素苷多达600种，主要由6种花青素苷元衍生而来。花青素苷合成途径是迄今为止研究得最为清楚的植物次生代谢途径之一，它的合成首先取决于类黄酮代谢途径的生成，花青素苷种类的多样性则源于其不同分支途径的形成，在花青素苷元基本骨架上不同位置取代基的差异形成了多种多样的花青素苷。在花青素苷生物合成过程中，分支点酶的竞争机制和关键酶的底物特异性使花青素苷的种类及相应的花色表型具有种属特异性。花青素苷合成后需要转运到液泡中被包裹成色素体，植物细胞中的液泡积累和贮存色素体的能力是影响花青素苷呈色的重要因素，因此，花青素苷在花瓣中的最终呈色还受液泡pH、助色素含量以及金属离子的络合作用等多种细胞内因素的影响。目前，已经在多种植物中获得了与花青素苷合成及呈色相关的结构基因和调节基因，并解析了其功能，成功获得了一些转基因花卉，但是这些基因调控表达的机制，包括转录水平和转录后水平的调控、DNA 序列本身的差异和 DNA 甲基化修饰的调控机制等仍不清楚，转基因植株花色改良的程度也很有限，对于如何将这些机制应用于花色改良的转基因育种也是一个前沿的课题。花青素苷对园艺作物器官呈色机制的解析有助于对花朵呈色机制的理解，观赏植物中花色形成机理的研究对于园艺作物器官呈色机制的解析同样具有重要的参考价值。因此，本文以观赏植物为例，从花青素苷合成分支途径形成的机理、花青素苷生物合成途径的遗传调控机理以及影响花青素苷呈色的主要因素及其遗传调控机理3个方面，对影响植物花朵呈色的机制进行了综述，并对近年来基于花青素苷代谢和呈色机理的花色改良分子设计育种，尤其是国际上广泛关注的蓝色花育种进行了梳理和总结，以期为定向培育具有新奇花色的观赏植物新品种提供参考。
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