Study On The Interspecific Relationships Of Cornus Subg.Syncarpea Based On The Whole Chloroplast Genome

Cornus subg.Syncarpea has a wide distribution and large morphological differences.The phylogenetic relationship between species has not been fully studied so far.As the field statistical investigation of the traits of the Cornus subg.Syncarpea,combined with the analysis of chloroplast genome,the interspecific relationship of the Cornus subg.Syncarpea was comprehensively analyzed.In order to analyze the traits of the Cornus subg.Syncarpea,the commonly used morphological researchThe methods combining metric traits and non-metric traits are used to study and analyze the leaves with obvious morphological differences.The analysis of the traits of Cornus subg.Syncarpea show that the measurable traits of Cornus hongkongensis subsp.melanotricha,Cornus hongkongensis,Cornus hongkongensis subsp.elegans and Cornus hongkongensis subsp.gigantea are relatively small.The difference in measurable traits between Cornus hongkongensis and Cornus hongkongensis subsp.gigantea is relatively small.The results of non-metric trait analysis were similar.In this study,the total DNA was extracted from the collected samples of ten species of Cornus subg.Syncarpea,and then the chloroplast DNA was isolated from the total DNA,and then the quality detection,DNA library construction,sequencing,gene assembly and other steps were carried out.And finally annotated the chloroplast genomes of 10 assembled plants of Cornus subg.Syncarpea.For the first time,the chloroplast genome sequences of 10 plants of Cornus subg.Syncarpea were obtained.The size of the ten chloroplast genome sequences is 156,965-157,380 bp,with a typical tetrad structure,which can be divided into four regions,LSC region(large The size of the single copy region is 86,296-86,689 bp,the size of the SSC region(small single copy region)is 18,386-18,454 bp,and the size of IRa and IRb(a pair of inverted repeat regions)is 26,112-26143 bp.All ten chloroplast genes encode 131 functional genes,including 86 protein-coding genes,8 r RNA genes,and 37 t RNAs.The total GC content in the whole genome of ten species ranges from 38.12%-38.17%,the average GC content is 38.145%,and the total GC content range is 0.05%.The comparison of the structural features of the chloroplast genomes of ten species of Cornus subg.Syncarpea showed that they were all highly conserved,while the comparison of the IR region boundary revealed that only the ndh F gene and the ycf1 gene in the SSC region were different.The number of simple repetitive sequences in the chloroplast genome sequence of ten species is not many,mainly distributed in the LSC region,accounting for 80%-89%,followed by the SSC region,accounting for 7%-14%,and the IR region is the least.0-8%.In order to clarify the phylogenetic status of the ten species in Cornus subg.Syncarpea,five data sets including the whole chloroplast genome,coding region,LSC region,intron and IR region sequence were used to construct Phylogenetic tree based on the maximum parsimony method(ML).Among them,the phylogenetic tree constructed with the whole chloroplast genome,in addition to plants of Cornus subg.Syncarpea,also used other 12 extra-groups as references.Among the five topological structures formed,the overall topological structure of the 10 species of Cornus subg.Syncarpea has little difference.According to the constructed phylogenetic tree,it is concluded that the Cornus hongkongensis flower is closely related to Cornus hongkongensis subsp.gigantea.Combining the trait analysis of the Cornus subg.Syncarpea and the results of chloroplast genome analysis,it can be concluded that Cornus hongkongensis and Cornus hongkongensis subsp.gigantea belong to the same species.There is a theoretical basis.For Cornus hongkongensis subsp.melanotricha,Cornus hongkongensis subsp.elegans,Cornus hongkongensis subsp.ferruginea and Cornus hongkongensis subsp.tonkinensis,there is not enough theoretical basis to prove that they belong to the same species.