Unpllinated Ovule Culture Of Ground-cover Chrysanthemum(Chrysanthemum×grandiflorum)

Ground-cover chrysanthemum is an important landscape ground cover plant. Because of self-incompatibility, it is difficult to obtain homozygous inbred lines. Pure lines can be quickly obtained by anther or unpollinated ovule culture. It has been reported that haploids can be obtained by anther culture of ground-cover chrysanthemum, in which ovule culture has not been reported. The aim of this study is to develop an ovule culture system to produce haploid of ground-cover chrysanthemum, and understand the mechanist of gynogenesis. The effect of various treatment for ovule culture was investigated. Stomata character and plant morphology of different ploidy have been compared. The embryology and the procedure of the induction of gynogenesis were studied. The main results were as follows:1. Chrysanthemum inflorescence morphology had correlation with embryo sac development period. When the ray florets fully unfolded and vertical to receptacle, the embryo sac is mature. Ovules collected when ray florets was fully opened and disk flower was about to open induced the highest frequency of callus induction.2. Different genotypes of ground-cover chrysanthemum induced in different mediums. WS was benefit to cultured in the medium:MS+6-BA2.0mg/L+NAA0.5mg/L+sucrose30g/L or MS+6-BA2.0mg/L+NAA0.5mg/L+sucrose60g/L. PD was benefit to cultured in the medium: MS+6-BA1.Omg/L+NAA0.5mg/L+sucrose30g/L. Differentiation medium was MS+6-BA2.0mg/L+NAA0.05mg/L+30g/L sucrose.3. Ovule callus induction rate under light condition was significantly higher than under the dark conditions.4. The low temperature pretreatment can improve callus induction to some extent. Cullus induction rate as high as76.25%was achieved after3days cold pretreatment at4℃.5.75regenerated plants were obtained in the study. The ploidy of20plants regenerated from WS were checked and obtained one haploid (n=3x=27), one tetraploid(2n=4x=36), one pentaploid (2n=5x=45) and an aneuploid(2n=5x-3=42).6. It was observed that antipodal cells were able to start division after3days culture, and then developed as the form of callus. The embryoid was also observed at micropylar end..