Abstract:

【Objective】 The interspecific hybridization barrier between cultivated chrysanthemum and diploid wild species were overcome by doubling chromosome, in order to transfer excellent traits or genes of the diploid wild species into chrysanthemum, broaden the gene pool in chrysanthemum, and achieve novel germplasm. 【Method】 Artificial hybridizations were made between the diploid and tetraploid of Chrysanthemum nankingense (♂) and cultivated chrysanthemum (Ch. grandiflorum ‘Zhongshanzixing’) (♀). Cytology analysis was used for hybrids identification and some characters of the hybrids were analyzed. 【Result】 Pollen viability of the diploid and tetraploid were higher and the pollen grains could germinate on the stigma of Ch. grandiflorum ‘Zhongshanzixing’ well. But no seed was obtained in the combination between the diploid of Ch. nankingense and Ch. grandiflorum ‘Zhongshanzixing’ while a number of interspecific hybrids were obtained by crossing tetraploid Ch. nankingense with Ch. grandiflorum ‘Zhongshanzixing’. The chromosome number of Ch. grandiflorum ‘Zhongshanzixing’, tetraploid of Ch. nankingense and their hybrids were 54, 36, and 45, respectively. The chromosome commonest configurations at metaphaseⅠ per pollen mother cell in Ch. grandiflorum ‘Zhongshanzixing’, tetraploid Ch. nankingense and their hybrids were 27Ⅱ, 1.70Ⅰ+13.23Ⅱ+0.03Ⅲ+ 1.90Ⅳ and 5.32Ⅰ+13.84Ⅱ+2.79Ⅳ+0.16Ⅵ, mainly with bivalent. Plant height, leaf width, petiole length of hybrids were significantly positive in mid-parent heterosis of hybrids, while their internode length, leaf index, inflorescence diameter, floral disk diameter, and floret number were significantly negative in mid-parent heterosis. 【Conclusion】 Doubling the chromosome of Ch. nankingense could overcome the distant hybridization barrier with the cultivated chrysanthemum.

Key words: Chrysanthemum×grandiflorum')">Chrysanthemum×grandiflorum, tetraploid of Chrysanthemum nankingense, interspecific hybrdization, meiosis, character