Genetic Diversity Analysis Of Aquilaria Sinensis Population Based On SSR Molecular Markers

Aquilaria sinensis is the plant from the Aquilaria genus of Thymelaeaceae and mainly distributed in the provinces of Hainan,Guangdong,Guangxi and other(sub)tropic regions.After natural injury or human injury,this plant will form the worldwidely famous resin,agarwood.As traditional precious spices and rare medicinal materials,agarwood presents high medicinal,economic and cultural value.However,by the reasons of man-made predatory exploitation and habitat loss,the wild resources of A.sinensis were gradually harvested in the past two decades.In addation,the genuineness of medicinal agarwood was also lost seriously,which restricted the sustainable utilization of A.sinensis resources and the development of agarwood industry.Selecting high-quality cultivated germplasm for artificial cultivation is the effective pathway to realize the protection and sustainable utilization of A.sinensis resources.To investigate the problems in agarwood industrialization,such as limited genetic background research and unclear genetic relationship of A.sinensis varieties,286 samples from 61 populations of A.sinensis from different regions in Hainan Island were collected to identify the leaf phenotypic traits and develop the SSR markers.Based on the genome and transcriptome of A.sinensis,the characteristics of SSR sequences were analyzed and SSR molecular markers were developed.Subsequently,the genetic diversity of A.sinensis populations in Hainan Island based on SSR molecular markers were analyzed for laying the foundation of the genetic basis evaluation of A.sinensis germplasm resources and its new varieties breeding.These results also contributed to realize the resource protection and sustainable utilization of A.sinensis resources.The main results of the study are as follows:1.The phenotypic traits of A.sinensis population were analyzed and evaluated by genetic diversity index,coefficient of variation,correlation analysis and cluster analysis.The results showed that the genetic variations among these populations in leaf phenotypic traits such as leaf length,leaf width and chlorophyll content.The variance analysis of the phenotypic traits of the leaves of A.sinensis demonstrated that the differences among the groups were significant(P < 0.01),indicating that the phenotypic traits of the leaves of A.sinensis were diversity in genetic variation among individuals in the group.2.SSR markers were developed based on the genome and transcriptome data of A.sinensis.The sequence features of SSR repeat motifs detected from the genome sequence of A.sinensis showed that dinucleotide had the highest repetition rate,which was consistent with the results of visual analysis,Dinucleotide repeat SSR sequence was focused on molecular marker development of A.sinensis.A total of 9362 SSR loci were identified in 128712 unigene transcripts.The largest number of dinucleotide repeats were found in SSR sequences,which types were AG/CT or AC/GT were and their repeats loci were mainly 5～11.3.SSR primers were developed based on the genomic SSR sequence,and 8 pairs of specific SSR primers were selected to analyze the genetic diversity of A.sinensis population.The Shannon index(I)(0.2599 ～ 0.9107)and Nei’s gene diversity index(H)(0.1775 ～0.5525)of 61 populations showed that the genetic diversity was high and the genetic variation was rich.There were large genetic variations within and between populations,and the genetic variation within populations was greater.The Shannon information index(I)was0.6165～1.0656 among the 16 geographical regions,which showed that the population resources of BT were more abundant and diversified than other places.4.The analysis of population structure showed that 286 materials were divided into three groups.The genetic structure map of the A.sinensis population was constructed with the optimal K value and the results present that the ancestral components of a small number of samples were very pure and most of the sample populations were seemed to be hybridized by2～3 ancestral subgroups.The final result suggested that gene penetration and genetic differentiation within the A.sinensis populations.