A Taxonomic Study Of China-distribution Subtribe Ligustrinae(Oleaceae)

Ligustrum Linn.and Syringa Linn.are belong to the Syringa tribe(Trib.Syringeae),Oleaceae in the taxonomy system of Fo C.In the latest study and the taxonomic system used in this article,they are both large genera belong to the Subtribe Ligustrine.Ligustrum plants are the main components of evergreen/deciduous broad-leaved forests or shrubs in many places.Some species have ornamental,medicinal,or potential scientific research value,and almost the vast majority of species are native to China.Similarly,China is also the modern distribution center of Syringa.The corolla of some wild lilac are raw materials for extracting essence and preparing high-grade spices.Therefore,conducting systematic and taxonomic research of genus Ligustrum and Syringa in China can lay the foundation for the comprehensive revision of the world Ligustrum and Syringa and the establishment of a more natural and objective taxonomic system of the genus Ligustrum and Syringa,and provide theoretical basis and guidance for the rational development of the natural resources of them.As a group with high potential scientific research value and economic benefits,there have been significant problems in the taxonomy of these two genera.For instance,the existing taxonomy systems of the genera Ligustrum and Syringa are almost entirely based on morphological and a small amount of cytological and sporopollen studies,which not only cannot clearly and accurately delimit species,but also fails to solve the phylogenetic relationship of the vast majority of groups in the genus.In recent years,although studies on morphology,systematics,cytology,and palynology of these two genera have been continuously published and accumulated,systematic and comprehensive studies are still lacking.The latest molecular phylogenetic research results of Oleaceae indicate that Ligustrum and Syringa do not form a sister group,but a single lineage together,and Ligustrum is located within the phylogenic framework of Syringa.Therefore,in the following text,we use Subtribe Ligustrinae refers to Ligustrum plus Syringa.at the same time,it is urgent to establish a more reasonable and natural taxonomic system for the Subtribe Ligustrinae based on more comprehensive molecular systematics and morphology,and to revise the original taxonomy system.This study conducted taxonomic studies on morphology,molecular systematics,cytology,and palynology of the China-distributed Subtribe Ligustrinae,and identified for the first time that the Ligustrum and Syringa jointly constitute a monophyletic Subtribe Ligustrine,and all the Ligustrum are included within the Syringa branch.In this paper,this brand-new taxonomic system is named 2023 Subtribe Ligustrine taxonomic system,and the Subtribe Ligustrine is divided into 6 genera,Namely [in systematic order]: 1)Syringa(Include Syringa oblata,Sringa vurlgare and the related species);2)The genus Neosyringa(Included Ser.Pinnatifoliae);3)Pseudosyringa(including most species within the “general Syringa”);4)Ligustrina,It is a morphological transitional group of Lilac and narrow Ligustrum;5)Parasyringa(including the only species Ligustrum sempervirens);6)Ligustrum,Contains all Ligustrum species except Ligustrum sempervirens.At the same time,we reconstruct the taxonomic system of the narrow Ligustrum,divide the Pseudosyringa into 2 sections,and divide the Ligustrum into 10 clades,and organize its systematic relationships and synapomorphy.This study not only clarified the phylogenetic relationships among the main branches within the genus,but also sorted out the phylogenetic relationships of some respectively species,inferring their evolutionary and migratory history and processes through floristic geography,chromosomes,etc.,and laying a foundation for morphological evolution research and establishing a more comprehensive and complete classification system.In addition,among the chloroplast genome data used for phylogenetic analysis in this article,Ligustrum robustum subsp.chinense,Ligustrum sinense var.myrianthum,Ligustrum japonicum ’Howardii’,Ligustrum leucanthum,Ligustrum strongylophyllum,Ligustrum fengjieense and Ligustrum delavayanum were first sequenced and reported."Among them,Ligustrum fengjieense is a new species published by the author during his post–graduate based on morphology.This study made up for the defect of the former that no gene sequencing was performed,and determined its systematic location,further improving and optimizing the phylogenetic tree of Oleceae.".