Study On Phylogenetic Relationships Of Michelia Linn.in China

Michelia belongs to Magnoliaceae,which has important value for wood,medicine,oil and landscaping.There is a large range of morphological variation and some interspecific hybridization in this genus,which leads to the difficulty of classification.There are disputes in the intra-genus grouping and interspecific systematic relationship and species status.In this research,we studied the phylogenetic relationships of 40 species in this genus,based on the combined sequence of 5 chloroplast DNA spacer sequences(psb A-trn H?psb B-H?trn L-F?trn C-ycf6?trn D-E),simplified genome sequencing(super GBS)and morphological branch analysis.The results showed as follows:The combined length of chloroplast fragment was 3313 bp,including the number of Variable sites was 133,the number of Parsim-informative substitutions was 60,the average of G and C was36.58%.Phylogenetic results showed that the 40 species of Michelia were grouped into 7 branches.Michelia odora and other plants of Michelia constituted a monophyletic group,which did not support the independent genera of M.odora.The relationship between Michelia caloptila and Michelia Fujianensis is far away and the combination of M.caloptila and M.Fujianensis is not supported.According to the haplotype,53 individuals had their own haplotypes.According to the phylogenetic network tree analysis,the gene tree is conflict and reticular evolution in Michelia elegans and Michelia×alba,May the reason is that the M.elegans and M.×alba are hybrid.There were gene conflicts and reticular evolution in the species,but no gene conflicts and reticular evolution in the species.There was no interspecific gene conflict and reticular evolution between M.Fujianensis and other species from three different habitats,There were gene conflicts and reticular evolution between M.odora and other species,There is a complex reticular evolution phenomenon in the genus Michelia.The BEAST divergence indicates that the Michelia and Yulania diverged between the late Eocene and the middle Oligocene(29.8968-46.2531Mya).M.elegans was the first species to diverge from the Michelia and the time is about 29.8968 Mya.During the Miocene(13-17Mya),the Michelia showed rapid differentiation.That climate change is likely to be affected Michelia on the origin of species and diversity increased a major driving force,the results and predecessors' studying results,namely the Oligocene to middle-late Miocene,global warming leads to the Antarctic glaciers covered area is narrow,lead to the vast majority of north temperate forest species in Asia is consistent with that of origin and diversification.2)High-throughput sequencing was conducted based on Super GBS technology,and 34.55 GB of valid data were obtained.A total of 236,473,346 Cleanreads were obtained from the original GBS sequencing data of all samples,with an average reads of 4461,761 and an average Raw Base of 0.73 GB.Clean Base 0.65 GB.The average Q20 of each sample was more than or equal to 93.83%,and the average Q30 was more than or equal to 85.78%.The sequencing quality was high,and the average GC content of each sample was 45.02%.A phylogenetic tree was constructed by adjacency method based on 317833 SNP loci obtained.The results showed that the 51 samples were divided into 6 branches,To support the incorporation of M.odora into the Michelia;Support the independence of M.caloptila from M.Fujianensis.It is necessary to expand the sampling range for further study on the variation of M.skinneriana and the relationship with M.caloptila.The results of phylogenetic tree and genetic structure analysis diagram are mutually verified.3)The morphological characteristics of the species were grouped into 6 branches,which was consistent with the results of cp DNA and SNP clustering based on high-throughput sequencing.The form of M.skinneriana is rich in variation.It is difficult to distinguish some individuals from M.caloptila in morphological characteristics,and further research is needed.4)Based on the combined chloroplast fragments,Super GBS phylogenetic analysis and morphological character cluster analysis were combined.We support the division of Michelia into 6 groups,which is quite different from the system proposed by Law.