Study On The Genetic Diversity Of Caryopteris Mongolica Natural Population

Caryopteris mongolica is a perennial deciduous shrub of the Verbena family Caryopteris,with ornamental,medicinal,forage and other values,and it is rare species under the national third-level protection.At present,the research on Caryopteris mongolica mainly focuses on physiological characteristics,breeding and cultivation,community structure,etc.,while the research in the field of genetics diversiy is relatively lagging behind.so,In this study,the molecular genetics of 13 natural populations of Caryopteris mongolica were studied by using chloroplast genome information and transcriptome sequencing technology.At the same time,a number of polymorphic EST-SSR molecular markers were developed to provide powerful SSR molecular tools for revealing the genetic characteristics of Caryopteris mongolica.The main findings are as follows:(1)Based on the 151707 bp genome information of C.mongolica chloroplast,a total of 31 cp SSR loci were found,of which the number of single nucleotide was the most and the number of trinucleotide was the least.Single nucleotide was distributed in LSC,SSC and IR regions of chloroplast genome,while trinucleotide was only found in LSC region.Thirty-one cp SSR loci were designed as primers for capillary test,and eight pairs of polymorphic primers were screened out.(2)Eight pairs of cp SSR primers were used to perform UPGMA cluster analysis on C.mongolica,and the population was clustered into four categories: WH and ALS were grouped together as one group;HLB and NX are divided into two groups;the remaining 11 groups are grouped into one group.(3)In this study,the stems and leaves of C.mongolica were used as samples for Illumina sequencing for the first time,and a total of 46.7Gb of Clean Data transcriptome data were released.After assembly,60293 Unigenes with a total length of 59,742,218 bp were obtained,which were annotated into the NR,COG,KEGG and GO databases respectively,at the same time,EST-SSR sites were discovered based on transcriptome information,19839 EST-SSR markers were obtained,1500 pairs of primers were designed,100 pairs of primers were screened with 20 templates,and finally 13 pairs of highly polymorphic EST-SSR primers were used for genetic analysis and filled the gap of SSR molecular markers in Caryopteris mongolica.(4)The genetic diversity analysis of 13 different geographical locations of C.mongolica samples was carried out by using the above 13 pairs of polymorphic C.mongolica EST-SSR primers.The results showed that: there were 9 pairs of EST-SSR primers whose PIC values were >0.5,indicating high polymorphism,the primers had good discriminating power;the population polymorphism analysis showed that the mean number of alleles(Na)is 3.36,the mean number of effective alleles(Ne)is 2.33,the mean observed heterozygosity(Ho)is 0.43,the mean expected heterozygosity(He)is 0.47,and the mean value of Shannon’s information index I is 0.79.The level of genetic diversity is high,and the genetic diversity level of the population: SLQ population is the highest,HLB is the lowest.(5)Based on AMOVA analysis: it was concluded that intraspecific variation highly interspecific variation of C.mongolica population.F statistic analysis shows that C.mongolica has a relatively high level of differentiation;the UPGMA cluster map based on EST-SSR markers shows that the population is divided into three branches,the NX population is divided into one branch,and the second branch is divided into two Group:ALS and ETK are grouped together,and WH is grouped together;the third branch is divided into two grouped together: BLG and HLB;EL,DS,XS,SLQ,LJD,DQS,and JB groups are grouped together.In addition,Mantel test found that genetic distance was significantly positively correlated with geographic distance.