SSR-based Analysis of Genetic Diversity and Quality Trait-related Markers of 69 Picria felterrae Germplasm Samples / 中国实验方剂学杂志

ABSTRACT

Objective:Sixty-nine germplasm samples of Picria felterrae collected from the main producing areas in Guangxi were subject to genetic diversity and genetic relationship analyses using the simple seguence repeat(SSR) molecular marker technology and good germplasm genes associated with the content of picfeltarraenins were screened so as to provide references for germplasm resource evaluation, phylogenetic analysis, and molecular mark assisted breeding of that species. Method:20 pairs of randomly selected primers were amplified based on the transcriptome sequencing technology. The genetic diversity of and genetic relationship between the 69 samples were analyzed using the genetic polymorphic information for each marker locus, and one-variable linear regression and multiple stepwise regression analyses were performed to screen molecular markers associated with the content of picfeltarraenins. Result:The amplification using the 20 pairs of SSR primers produced 76 alleles, 3.8 alleles for each locus on average, higher than effective alleles (1.969 2), and the rare allele rate was 38.2%, suggesting that the alleles distributed unequally. The polymorphism rates of alleles varied between 0-59%, with an average of 38.24%, showing a great difference among loci. The polymorphic information content (PIC) varied between 0-0.621 1, with an average of 0.378 0.Shannon polymorphic information index varied between 0-1.240 1, with an average of 0.759.Nei's gene diversity index (Nei) varied between 0-0.682 3, with an average of 0.440 9.P21 had the highest level accompanied with the lowest P7 for the above three indexes, and significant genetic diversity differences were identified among the loci. For all loci, the mean observed heterozygosity was 0.382 4, lower than the average expected heterozygosity of 0.442 5, suggesting the loss of heterozygosity, the average genetic differentiation coefficient (Fst) was 0.365 9 and the average gene flow Nm was 0.433 2, suggesting a high genetic divergence and a low gene flow. The results of one-variable linear regression and multiple stepwise regression showed that there were 5 loci related to each of the picfeltarraenin IA and IB, and only 1 loci was associated with the content of both. Conclusion:There were significant differences in the genetic diversity of 20 SSR marker sites, and the 69 germplasm samples were greatly genetically differentiated and had low gene flow. From the selected 20 SSR markers 9 marker loci associated with the content of picfeltarraenin IA and IB were selected. The results can be used as a reference for phylogenetic analysis and selective breeding of Picria felterrae.