Creating New Germplasm Of Chryssanthemum By Using Intergeneric Hybridization

Chrysanthemum,(Chrysanthemum X morifolium), originated from China and cultivated world widely, is one of the ten most famous flowers in China and one of the four most popular cut flowers over the world. Chrysanthemum is most commonly used as cut flower, pot plants and bedding flowers. However, the plant is easily damaged by abiotic and biotic stresses, which reduce the productivity and result in economic loss. Thereby, it’s necessary to improving the resistance of abiotic and biotic stresses. But because of the gap between different two genuses, the obtained intergeneric hybrids usually can’t grow or bloom normally. To improve the chrysanthemum cultivars’resistance to abiotic and/or biotic stresses, the present study conducted the intergeneric hybridization between cut chrysanthemum and Artemisia japonica Thunb., Artemisia vulgaris, respectively. Additionally, to improve the ornamental value of F1hybrid of C. grandiflorum ’Zhongshanjingui’x Ajania przewalskii, we produced BC1F1progeny using ’Zhongshanjingui’ as the recurrent parent. The main results are as follows:1. To transfer the traits of salt and drought tolerance from Artemisia japonica Thunb. to cut chrysanthemum, we made an intergeneric hybridization between’Maoyan’(female parent) and Artemisia japonica Thunb.(male parent), one intergeneric hybrid of this combination was created using embryo culture. The morphology of the hybrid differed from that of either parent. The hybrid was vigorous, flowered normally and its flower and leaf shape resembled those of the chrysanthemum more than those of the Artemisia japonica Thunb. parent. The leaf width and length of the hybrid was in the middle of those of parents, and the plant height and inflorescence diameter are between Dendranthema morifolium ’Maoyan’ and Artemisia japonica Thunb., while its leaf colour and form was similar to that of’Maoyan’. Under the salt and drought stress, the appearance of hybrid and parents were compared, and the contents of chlorophyll (Chl), free proline (Pro) and malondialdehyde (MDA) in the leaves were analyed. The result showed that the salt and drought tolerance of the hybrid was significantly superior to that of their C. morifolium parent. Intergeneric hybridization clearly provides an effective method of cultivar improvement in cut chrysanthemum.2. In order to transfer aphid’s(Macrosiphoniella sanbourni) resistance and drought tolerance traits of Artemisia vulgaris L. to cut chrysanthemum, embryo rescue (12-15d post pollination) was used to overcome post-fertilization barriers and create the hybrid from the wide cross between C. morifolium’Nannongxiaoli’(female parent) and Artemisia vulgaris ’Variegata’(male parent). We obtained124seedlings, only19out of124were true hybrids. Their hybridity was confirmed by a combination of morphological, cytological, and resistance analyzes. The hybrids were vigorous, flowered normally, and their flower and leaf shapes resembled those of the cut chrysanthemum more than those of the mugwort parent. Cytological analysis revealed that there are45chromosomes in hybrids cell, which is the mean number of their parents. The hybrids showed much higher resistance to chrysanthemum aphid and drought than maternal chrysanthemum, and each hybrid differed in the tolerance to stresses, but all the hybrids are less tolerant/resistant to the stress than mugwort parent is.3. The hybrids between C. morifolium’Zhongshanjingui’and Ajania przewalskii have been obtained, the Fi hybrids showed improved resistance to cold, but the ornamental value was not as high as that of female parent. Thus, in order to improve the ornamental value of F1hybrid of C. morifolium’Zhongshanjingui’×Ajania przewalskii, we produced BC1F1progeny using’Zhongshanjingui’as the recurrent parent.17backcross hybrids were successfully obtained, they differentiated obviously from their parents in many morphological characters. There happened three flower types, i.e. anemone type, mid-anemone type and non-anemone type. The flower color, viz. orange, is nearly as same as the maternal chrysanthemum. The hybrids’leaf shape also differentiated severely, and the sizes of leaves were laid in the parents. The protocols including the number of emergent rhizomes over wintering period, the content of MDA and Pro under cold stress, were applied to test and compare the cold tolerance of the backcross hybrids and their parents. The results showed the hybrid lines obtained the cold tolerance from the male parent. Therefore, it is possible to improve the intergeneric hybrids ornamental value by backcross.