Evolutionary Divergence In Neolitsea(Lauraceae)based On Complete Chloroplast Genomes And Nuclear Ribosomal Cistrons

Genomic,evolutionary and biogeographical studies of complex,diverse and widely distributed plant groups are hampered by a number of technical and practical difficulties.This is especially true for major plant families in the tropics.Lauraceae are highly species rich with over 3000 species worldwide and are an important structural and evolutionary component of wet tropical forests.But unfortunately,they are in danger of extinction,as evidenced by the growing number of Lauraceae on the IUCN Red List recently.Lauraceae remain poorly known and difficult to identify,primarily due to the absence of clear vegetative characters that can aid in successful identification.The genus Neolitsea consists of nearly 100 species.China is a center of diversity for the genus with nearly 50 species distributed across the southern provinces.Little is known about the internal relationships of the genus or its exact position in the family,as higher generic relationships in Lauraceae remain unclear.In our study,we present the first complete plastome for the genus Neolitsea,using complete chloroplasts for 16 Neolitsea and 7 related genera produced by our ongoing project,we clarified the position of the genus Neolitsea in Lauraceae and confirmed its inclusion in the Laureae group by geting the whole chloroplast sequence with Mig-seq and NGS technology.We use orgasm,Geneious.OGDraw to do the feature analysis.Moreover we made SH-like ML tree with 23 species.We provide a first estimates of its genomic divergence from the rest of family.Phylogenetic trees were constructed by using five different data sets(small single copy.coding sequence,complete chloroplast,large single copy,nuclear ribosomal cistrons),which indicate that two large sisterclades define the relatioonships in the sampled species(Clade A:N.chuii,N.sericea,N.dealbata,N.ovatifolia,N.cambodiana,N.aurata and clade B:N.pinninervis,N.zeylanica,N.longipedicellata,N.shingningensis).The data failed to resolve relationship when using only coding sequence or large single copy.The combination of complete chloroplast and nuclear ribosomal cistrons data has the potential to solve the problem of intra-generic differentiation of Neolitsea and provides strong evidence to support the monophyly of Neolitsea.our studies demonstrate that the use of complete chloroplast,and the comination with nuclear DNA data,opens exciting opportunities to address evolutionary questions in Lauraceae.Finally,more extensive data of this large and complex plant family.will enable us to address the many questions on its evolution,ecology and conservation.