野菊舌状花形态变异的遗传分析

Genetic analysis of morphological variation of ray florets in Chrysanthemum indicum

舌状花是菊花头状花序的重要组成部分,其形态变异是造成菊花瓣型、花型多样性的重要原因,然而不同形态舌状花的起源及遗传规律尚不清晰。野菊(Chrysanthemum indicum)是栽培菊花起源的重要亲本,课题组前期通过种质资源调查获得了1株野菊突变株,其头状花序同时存在平瓣、匙瓣、管瓣3种瓣型,扦插繁殖后该特点保持不变,命名为CIZ株系。本研究构建了野菊突变株系CIZ和野生型CIW株系F代杂交群体,根据后代舌状花花冠筒基部合生程度(CTMD)探究舌状花形态变异遗传规律;同时统计以6种优选平瓣小菊为父本、野菊CIZ株系为母本杂交后代的瓣型,探究瓣型突变性状的遗传性及野菊CIZ株系用于瓣型育种的可能性。另一方面,为探究瓣型突变是否为嵌合性状,以平瓣、匙瓣、管瓣3种瓣型舌状花为外植体,观察再生植株的瓣型。结果表明,野菊CIZ株系和CIW株系杂交群体F代中都以平瓣类型为主,F代群体的CTMD表现为偏向于低值亲本的偏态分布;野菊CIZ株系与平瓣小菊杂交后代出现瓣型性状分离,野菊CIZ株系可作为菊花品种改良育种的重要材料;同时野菊CIZ株系平瓣、匙瓣、管瓣3种瓣型的再生植株开花后均表现为混合瓣型,平均CTMD无显著差异,表明该突变在花发育早期发生且为非嵌合性状。本研究为菊科植物舌状花变异遗传机制研究和菊花瓣型改良育种提供了重要的参考。

Ray floret is an important part of the capitulum of chrysanthemum, and its morphological variation is an important reason for the diversity of petal type and flower type in Chrysanthemum. However, the origin and genetic rule of ray florets with different forms are still not clear. Chrysanthemum indicum is an important parent of the origin of cultivated chrysanthemums. We have obtained a mutant C. indicum through germplasm resource investigation in the earlier stage, and the mutant C. indicum had three petal types on one capitulum at the same time, such as flat type, spoon type and tubular type. The above characteristic remained unchanged after cutting propagation and was named as CIZ strain. In this study, a hybrid population of Fgeneration of CIZ strain and wild type CIW strain was constructed. The genetic rules of ray floret morphological variation were investigated according to the corolla tube merged degree(CTMD) of offsprings. Besides, petal types of the offsprings crossbreeded by CIZ strain(the female parent) and six selected flat petaled chrysanthemum cultivars(the male parent) were counted to explore the heredity of mutant characteristics of petal type and the possibility of CIZ strain used in petal type breeding. On the other hand, the petal types of regenerated plants were observed to explore whether the petal type mutation was a chimeric trait, using ray florets of three different petal types such as flat type, spoon type and tubular type as explants. The results showed that, the flat petal type was the dominant type in Fgeneration crossbreeded by CIZ strain and CIW strain. The CTMD of Fpopulation showed a skewed distribution in favor of low value parent. The hybrid generations of CIZ strain and flat petaled chrysanthemum cultivars showed separation of petal type characteristics, and CIZ strain could be used as important material for the improvement and breeding of chrysanthemum varieties. The regenerated plants with three petal types(flat type, spoon type and tubular type) of CIZ strain showed mixed petal type after flowering, and there was no significant difference in the average CTMD value, indicating that the mutation occurred in the early stage of flower development and was non-chimeric character. This study provides important reference for genetic mechanism study of ray floret variation and improvement and breeding of petal shape for Compositae plants.