菊属植物分子系统学与菊花品种分子进化的研究

Chrysanthemum is a traditional flower in China and has been developed into a worldwide group of abundant ornamental cultivars. Although much work has investigated the origin of garden chrysanthemum, the phylogenetic relationships among species in this genus are unclear and the exact origin of Chrysanthemum is debated. In addition, it is often difficult to distinguish among mutants that have a common progenitor and among progenitors themselves owing to their large number and genetic variation. Furthermore, there is no universal identification system for Chrysanthemum taxonomy. Molecular data would provide a better understanding of plant evolutionary history. Single- and low-copy nuclear genes are less likely to be subject to concerted evolution than high-copy nuclear genes. Thus, the former genes are ideal tools to examine gene evolution in diploids and polyploids. We conducted a molecular phylogenetic analysis of various diploid and polyploid Chrysanthemum species to gain a better understanding of the evolutionary history of Chrysanthemum. Multiple genes, including five low-copy genes (ADH, CYC, LEAFY, RPB2, and PHY) and two plastid genes (the chloroplast matK gene and the mitochondrial nad1 gene), were explored to reconstruct the phylogenetic relationships of Chrysanthemum. Separate and combined analyses were performed using the maximum parsimony, maximum likelihood, and Bayesian inference methods to better understand the phylogeny and evolutionary history of the Chrysanthemum genus, how polyploid species formed, and the origin of the chrysanthemum genome; to position the genus in the Chrysanthemum and establish the relationship among wild relatives and cultivar chrysanthemum species combining the datas of karyomorphology of interphase nuclei and chromosome numbers. These investigations will help to develop and utilize wild chrysanthemum variety resources. Furthermore, according to how well the phylogeny analysis can evaluate specific genes, this could provide suitable DNA fragments for chrysanthemum identification and taxonomy, contribute valuable information for identifying species in other plant taxonomic groups, and help determine the standard DNA barcode in chrysanthemum.

菊花是中国传统名花，也是世界上品种最丰富的栽培植物之一。迄今由于缺少足够的遗传学信息，关于菊花起源的野生亲本始终不甚清楚，对菊花起源的方式众说纷纭，这就使菊花品种分类和鉴定困难重重。本研究拟以8种野生菊属植物（野菊、毛华菊、紫花野菊、甘菊、菊花脑、异色菊、神农香菊和小红菊）为材料并结合部分菊花品种，选取5个低拷贝核基因（LEAFY、CYC、PHY、ADH、RPB2）和叶绿体matK基因、线粒体nad1基因序列为分子标记，采取独立和多基因合并分析，构建菊属植物系统发育关系。结合细胞学研究，分析多倍体进化途径和基因组起源问题，探讨菊属植物分子进化和菊花品种演化历程，进而分析参与菊花起源的亲本种。这一研究不仅可以为菊花起源的深入研究提供更多证据，对于有效利用野生菊属植物种质资源进行菊花品种改良也具有实际意义，还可为菊花品种分类和鉴定提供DNA序列信息，有助于筛选适用于菊花品种分类的DNA条码。

菊花是中国传统名花，也是世界上品种最丰富的栽培植物之一。由于缺少足够的遗传学信息，关于菊花起源的野生亲本始终不甚清楚，对菊花起源的方式众说纷纭。本研究以8种野生菊属植物为材料并结合部分菊花品种，利用5个低拷贝核基因和2个细胞质基因为分子标记,对菊属植物的系统发育关系进行了分析。结果表明：多倍体野生菊属植物由同源加倍或异源加倍两种方式形成；杂交和异源多倍化在栽培菊花起源中发挥重要作用；甘菊、紫花野菊、银背菊、菊花脑和野菊等可能是一些菊花品种的直接起源亲本之一；野菊很可能参与了大多数栽培品种的起源；菊花很可能是多个父本、多次多地起源；人为活动在菊花品种演化中发挥重要的作用。这一研究为菊花起源的深入研究提供更多证据，为有效利用野生菊属植物种质资源进行菊花品种改良提供了理论基础。

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