A Phylogenetic Study On The Genus Ophiorrhiza

Ophiorrhiza L.is a medium-sized genus in Rubiaceae,with a total of about 200 to 300 species.Ophiorrhiza and Spiradiclis Blume are very similar in morphology and are traditionally placed in Ohiorrhzieae,Rubiaceae.In recent years,with the deepening of molecular phylogeny in Rubiaceae,recent research results show that the samples of Ophiorrhiza are interspersed with Spiradiclis and Keenania Hook.f.,which leads to the controversy of the boundary division of Ophiorrhiza.This study intends to explore the phylogenetic relationship between Ophiorrhiza and its related genera and determine the category of this genus through macromorphology,micromorphology and molecular phylogeny.The main results are as follows.1.The results of macroscopic morphology study showed that the plants of Ophiorrhiza,Spradiclis and Keenania had a large variation range in morphological characteristics such as habit,leaf,stipule,inflorescence and flower,but the comparison results were similar,and the three had a large overlapping range.The capsule is flattened on both sides,which is the biggest recognition point of Ophiorrhiza.However,in the comparison results,the author found that the fruits of S.emeiensis and S.malipoensis are also flattened on both sides,which provides support for the rationality of integrating Spiradiclis into Ophiorrhiza.2.The results of comparative study on micromorphology showed that the leaf epidermal cells of Ophiorrhiza and Spiradiclis were irregular and polygonal,the vertical peripheral wall is mainly wavy and flat,Stomatal apparatus only distributed in the lower epidermis.The types of stomatal apparatus were double ring flat type,all of which belonged to mesogenic origin.Stomatal density and stomatal index varied greatly in the two genera;The shape of the seed is mainly irregular,the surface decoration is honeycomb,and the vertical and flat peripheral walls have high similarity in style.3.The results of molecular phylogeny revealed that the phylogenetic trees constructed by ITS-ETS,ndhF-rps16 and all fragment joint genes of Ophiorrhiza,Spiradiclis and Keenania showed that Ophiorrhiza,Spiradiclis and Keenania were inlaid with each other to form a good monophyletic group.Most samples of Ophiorrhiza and Spiradiclis were inlaid with each other to form branches with certain statistical support;Two species of Keenania and some species of Spiradiclis form a branch.Based on the research data of macromorphology,micromorphology and molecular systematics,it is supported to incorporate Spiradiclis into Ophiorrhiza.Combined with the research data of macro morphology and molecular systematics,it is supported that Keenania is also incorporated into Ophiorrhiza.