Systematic Studies On Eragrostis

Eragrostis belongs to Chloridoideae of Poaceae and widely distributes in tropical and temperate regions of the world.It can be used as forage and also have medicinal value.Research on Eragrostis is very little in our country,mainly concentrats on the germplasm resources and resistance.Systematic position of Eragrostis has been controversial and the relationship between Eragrostis and its relatives is uncertain.To study on the systematic position of Eragrostis,75 taxa representing 35 genera were chosen as materials.Our research concentrated on micromorphological characters of lemma and caryopsis,molecular phylogeny based on ITS and matK.The species division of materials in experiments is based on ?Flora of China?.The results were as follows:Lemma micromorphological characters were investigated using Scanning Electron Microscopy.Five types of lemma micro morphological characters were reported here.The character of Eragrostis is: long cells are tubular,side walls are parallel,end walls are vertical,the wall of long cells are moderately thickened,slightly undulating or moderately undulating.Paired short cells,shape of subsidiary cells are low dome-shaped or low triangular,long-base Chloridoid-type microhairs,silica bodies are saddle-shaped,dumb-bell or cross-shaped,prickles persistent and lack of macro-hairs,papillae and hooks.32 characters were selected for phylogenetic analysis based on NTsys,Harpachne was embedded into Eragrostis.We supported subsuming Harpachne harpachnoides within Eragrostis.Caryopsis micromorphological characters were investigated using Scanning Electron Microscopy and anatomical lens.Six types of caryopsis micro morphological characters were reported here.The character of Eragrostis is: the length of caryopsis is about 1 mm,the colour of caryopsis is yellow,brown or yellow-brown,the shape of caryopsis is elliptic or spherical,the type of compression usually lateral or no,ventral face is slightly convex,ratio of hilum is 1/3 to 1/2,stylopodium persistent,hilum is round or oblong,surface sculpture is rectangular reticulate.35 characters were selected for phylogenetic analysis based on NTsys,Harpachne was embedded into Eragrostis,formed a clade together with Enneapogon.We supported subsuming Harpachne harpachnoides within Eragrostis.Nuclear ITS sequence and plastid matK sequences were used to conduct a molecular phylogenetic study using maximum likelihood and Bayesian.Carex albursina was treated as the outgoup.The tree divided into two segments in Chloridoideae,one contained Enneapogon,Eragrostis and Harpachne with bootstrapping of 0.998/1,Harpachne is embedded into Eragrostis with bootstrapping of 0.991/1.In the other one,Zoysia,Spartina,Sporobolus and Crypsis formed a small clade with bootstrapping of 0.995/1.Tragus,Buchloe,Muhlenbergia,Eleusine,Leptochloa,Enteropogon,Chloris,Dinebra,Orinus,Cleistogenes,Acrachne,Dactyloctenium and Tripogon formed a clade together.We supported subsuming Harpachne harpachnoides within Eragrostis.According to the morphological study of caryopsis and lemma,based on phylogeny tree of ITS and matK,Harpachne should be canceled,Harpachne harpachnoides should be put in Eragrostis,they formed a small Eragrostideae together.