Chrysanthemum (Chrysanthemum spp.; Asteraceae, Anthemideae) is not only a traditional Chinese flower, but also one of the most important cut flower, garden flower, and potted ornamental floricultural crops in the world. Although a native from China (Editorial Committee of the Flora of China, 1983), chrysanthemums have been associated with various international cultures and have been widely cultivated for centuries for their beauty, fragrance, edibility, and medicinal values. Huge numbers of genotypes have been created by cultivation and breeding over thousands of years (Anderson, 2006).
Chrysanthemums are among the most important and valuable fall-blooming plants for their diversity of flower shapes, colors, and forms. Chen et al. (1995) started to breed new garden chrysanthemums in 1961, hybridizing dwarf cultivars with wild species through mixed pollination or open pollination. After generations of hybridization and selection, groundcover chrysanthemums were developed, and many outstanding cultivars were introduced to urban landscapes (Chen et al., 1995, 2005; Wang and Chen, 1990). The distinguishing features of groundcover chrysanthemums are compact sizes, abundant flowers, long bloom duration, and rich colors. They are also highly drought-tolerant.
To breed desirable chrysanthemum cultivars, it is important to select appropriate parents that are beautiful and genetically diverse. In addition, in consideration of the self-incompatibility of most chrysanthemums, the crossability of parents is important for cross-breeding. Breeders would have much better success in creating new cultivars if they knew the genetic relatedness of the parents before initiating crosses (Saxena et al., 2010). Molecular technology has been widely used in analyzing genetic relationships and diversity. For example, random amplified polymorphic DNA (RAPD) markers were used to analyze 18 chrysanthemum cultivars (Chrysanthemum ×grandiflora) (Qin et al., 2002). Miao et al. (2007) classified 85 popular chrysanthemum cultivars into six groups using intersimple sequence repeat analysis. In contrast, the AFLP technique is a much more highly polymorphic and more efficient method that has been widely used to detect genetic variation. Evolutionary relationships in the genus Chrysanthemum were analyzed by AFLPs (Zhou and Dai, 2002), and genetic variation in potted and garden chrysanthemum cultivars was also tested (Han et al., 2007; Liu et al., 2008; Wu et al., 2007). However, no reports of genetic variation between wild species and groundcover chrysanthemum cultivars have been published. This article reports the genetic relatedness of 12 wild species and 62 groundcover chrysanthemum cultivars as revealed through AFLP analyses.
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