Abstract:

This research is the first time developing SSR molecular markers based on whole genomic sequences of Jasminum sambac，analyzing the composition and characteristics of SSR loci in the whole genomic of J. sambac，and conducting genetic diversity analysis of 40 collected Jasminum germplasms and parentage relationship identification of 41 open pollination lines of J. sambac. The research results were as follows：a total of 140 803 SSR loci were detected in the whole genome sequences of single and double petal J. sambac using MISA software. There are five types of repeat motifs，the highest number of repeat types are dinucleotides and trinucleotides，87 785 and 46 735 respectively，accounting for 62.35% and 33.19% of the total SSR loci. The SSR loci that are common and have variations in single and double petal J. sambac are selected based on the reference genome of single petal J. sambac，1 847 pairs of primers were successfully designed using Primer v3.0 software，and 240 pairs of evenly distributed SSR primers were randomly selected. The mixed DNA of 8 Jasminum germplasms with significant genetic background differences was used as the template for amplification，and 14 pairs of polymorphic SSR markers were finally developed. Using the developed SSR markers，a total of 169 alleles were detected in 40 Jasminum germplasm materials. The average number of alleles per locus（N_a），effective number of alleles（N_e），Shannon’s Information Index（I），observed heterozygosity（H_o）and expected heterozygosity（H_e）were 12.1，4.067，1.772，0.505 and 0.725，respectively. The polymorphism information content（PIC）ranged from 0.378 to 0.817，with a mean of 0.702. Through UPGMA clustering，40 Jasminum germplasms were divided into three major groups at Nei’s genetic distance of 0.82. J. sambac and J. multiflorum were separately clustered into one group with Nei’s genetic distance of 0.66. Genetic structure analysis shows that 40 Jasminum germplasms can be divided into 3 groups，and there are some genetic exchange between groups. 41 open pollination lines and 14 candidate male parents of J. sambac were detected using the developed SSR markers，103 alleles were found. The mean value of N_a，N_e，I，H_o and H_e were 7.4，2.446，1.061，0.366 and 0.522，respectively. The PIC ranged from 0.159 to 0.744，with an average of 0.477，and 6 pairs of primers were highly polymorphic loci. The 55 test materials were divided into three major groups at a genetic distance of 0.82，with all tested maternal parents of J. sambac and their open pollination lines clustered in one group. At a genetic distance of 0.28，2 maternal parents of J. sambac were clustered together with their open pollination lines. Using Cervus v3.07 software to analyze the genetic diversity parameters of SSR loci in open pollinated lines，known maternal parents and candidate paternal parents，the cumulative exclusion probability increased with the number of loci. For the single parent known non-paternal exclusion probability（NE-2P），the cumulative exclusion probability of 14 loci is as high as 0.9962. When the confidence levels of candidate male parents and triplets were both 95%，30 out of 41 open pollination lines of J. sambac identified male parents，LOD values were positive. Of these，26 open pollination lines of J. sambac were identified as self-crossing offspring，86.67%，and 4 open pollination lines of J. sambac were identified as hybrid offspring，13.33%. All male parents of the hybrid offsprings are J. sambac‘Thailand Double Layers’.

Key words: Jasminum sambac, SSR molecular marker, parentage testing identification, genetic diversity, whole genomic sequences