Preliminary Study On Male Gametophyte Fertility Of Rosa Multiflora Thunb. And Cultivar 'Chunshui L?bo'

Rosa belongs to Rosoideae in Rosaceae.It plays an important role in appreciation such as colourful flowers,long bloom duration and strong adaptability.As an excellent ornamental plants,many new varieties with excellent characters has been produced.However the triploid germplasm resources has not been taken fully advantage of in rose breeding work.It is usually considered that triploid plant has high infertility due to abnormal meiosis,however more and more study shows that the triploid is not complete sterile.It was found that the triploid plants R.Multiflora Thunb.and 'Chunshui L?bo'(Chinese old graden rose)has higher fruiting rate in large breeding efforts.Thus the two Rosa plants deserve deep research to make the rose triploid germplasm resources bring in the breeding work,as well as provide a new thought of ploidy breeding.In this study,from the biological characteristics and pollen mother cell meiosis and abnormal behavior observation and sexual hybridization study to analyzes the two triploid plants sterility.The major results as follows:1.Pollen viability detection:The pollen germination rate was 66.72% at 5%sucrose concentration of R.Multiflora Thunb,and the rate was 10% at 20% sucrose concentration of 'Chunshui L?bo' The pollen tubes elongation situation in stigma detection shows that the pollen began to germinate after 8h,a larger number of germination after 10h,the tube reach the column in the upper after 24h and reach the style part after 48h,after 70h the tubes arrive the ovary to complete the whole process of fertilization.2.Stigma receptivity detection:The results of stigma receptivity of R.Multiflora Thunb.and 'Chunshui L?bo' shows that it was no receptivity or has lower receptivity.3.Meiosis observation of pollen mother cell:The results shows that both R.Multiflora Thunb.and 'Chunshui L?bo' have the abnormal meiosis behaviors,which R.Multiflora Thunb.contains lagging chromosome and triad and 'Chunshui L?bo'mainly for lagging chromosome,chromosome bridge,micronuelei,dyad,triad and so on.There was different frequency of all kinds of abnormal behaviors.But because of these irregular chromosome pairing,dyad and triad,the triploid meiosis may produce sterility pollen.4.Ploidy breeding:The test using two trioloid plants,R.Multiflora Thunb.and'Chunshui L?bo' with the diploid and tetraploid rose varieties to reciprocal hybridizations.Results shows that when the two trioloid plants as female,the seed fertility was zero.When the two triploid plants as male,the six combinations were higher seed setting rate,individual hybrid combinations can even reach 100%.62 F1 were obtained in hybrid test,7 plants were diploid,37 plants were triploid and other 13 plants were tetraploid.Combination with morphology features of F1,preliminary screening two triploid plants conform to the goal.Combine all results,two triploid plants R.Multiflora Thunb.and 'Chunshui L?bo'both have certain fertility,performance for female infertility and male gametophyte fertile.They can be used to hybridize proper male to achieve triploid introgression breeding in Rosa.