Complete Chloroplast Genome Sequence Of Manglietia Longirostrata In Magnoliaceae

In accordance with the classification system of the family Magnoliaceae by Sima and Lu(2012),Magnolia hookeri var.longirostrata D.X.Li et R.Z.Zhou ex X.M.Hu,Q.W.Zeng et L.Fu,was combined and restated as M.longirostrata by Sima Yongkang(2016),which was described as a new variety for the long-beaked apex of the follicles and scanning electron micrographs of pollen grains by Hu X.M.?Q.W.Zeng,and they only found one individual in Malipo County(23°03?29?N,104°42?53?E),Yunnan Province,China.As to which of the above classification treatments is more scientific,that is,whether it is a variety or a distinct species,further research is needed.In this paper,through the study of chloroplast genome to explore beaks Manglietia system location within the Magnoliaceae,fill the blank of the long beak of Manglietia chloroplast genome research,preliminary parsing the chloroplast genome structure,and has carried on the codon preferences,repetitive sequence and mutation loci,IR boundary,the chloroplast genome comparative analysis,has been clear about the beaks Manglietia classification status within the Magnoliaceae,at the same time for the species in species identification,genetic engineering and the development of molecular markers and population genetics research lay the foundation.The results showed that:1.The full length of the chloroplast genome was 160094 bp,which was a typical quadrant circular DNA with a GC ratio of 39.30%.131 genes were found after annotation,containing eighty-six proteincoding genes,eight rRNA genes and thirty-seven tRNA genes.2.There are 25 optimal codons,which are affected by both natural selection and mutation in the process of evolution,but natural selection plays a dominant role.3.A total of 41 SSR loci(microsatellite repeats)were detected,which were mainly divided into single,two,four and six base repeats.However,single base repetition was dominant,accounting for 86.03%.In terms of simple repeats,a total of 5 forward repeats and 4 palindromic repeats were detected in the chloroplast genome of M.longirostrata,but no reverse repeats were found.In terms of tandem repeats,19 tandem repeats with length from 15 to 24 and number of repeats from 2 to 8 were detected.4.The SNP loci and InDel loci were obtained from the comparison between M.longirostrata and M.ficifolia Sima?Tao Xu.The results showed that there were relatively few base variation loci among atp B-rbcL,matK and ndhF,and these sequence fragments were limited in the intergenera or subspecies relationships of Magnoliaceae.5.Because ycf1 spanned the SSC region and IRa region,a pseudogene was generated in M.longirostrata.IR boundary analysis showed that the difference of IR boundary between M.longirostrata and other 9 species was mainly due to the difference of JLB,JSB and JLA regions.The variation in JLB region was the expansion of rpl2 gene in IRB region.The variation of JSB region was the expansion of ndhF gene in SSC region.The mutation in JLA region was trnH gene inexpansion in LSC region.In other words,the main factors affecting the boundary between LSC and IR region are rpl2 and the inexpansion of trnH gene.The main factors affecting SSC and IR region are the size of ycf1 gene at JSA and the expansion of trnH gene.The size of ycf1 gene in JSA is also the reason for the difference between the two species.6.By comparing the chloroplast genomes of M.longirostrata and other 9 species of Magnoliaceae,we found that the variation degree of coding region was less than that of non-coding region in Magnoliaceae species,and the most mutated gene was ycf1 gene between 129 K and 131 K.The most important locally different gene sequences were 6 K-9 K(rps16-psbl),31 K-33 K(psbM-psbD),38 K-40 K(psbZ-rpsl4),48 K-52 K(rps4-ndhK),66 K-68 K(petA-psbE)and 117 K-120 K(ndhF-ccsA).7.Finally,the MrBayes method was used to cluster 30 different species of Magnoliaceae,which indicated that there was a close relationship between M.longirostrata and M.megaphylla and that there was a far relationship between M.longirostrata and M.hookeri.It should be considered as a distinct species.