Preliminary Study On The Taxonomy Of The Genus Acidosasa (Bambusoideae)

The genus Acidosasa B.M.Yang（Bambusoideae,Arundinarieae）,belonging to the family Poaceae,are mainly distributed in the south of the Yangtze River.Morphological traits of the tribe Arundinarieae are usually homogeneous,and its classification is still controversial.In this study,Based on the chloroplast genome data,the phylogenetic trees of the trib.Arundinarieae was reconstructed,and by using scanning electron microscopy（SEM）,micromorphological characters of abaxial leaf epidermis of 7 genera,including the genus Acidosasa 10 species and 1 variety,were observed.The main results were as follows:1.The chloroplast genome of Acidosasa was relatively conserved,consisting of LSC,SSC and IRa/b,and its length was 139667～139926 bp.Among the four basic structure regions,IR region has no difference,LSC region has the largest difference（175 bp）,and SSC region 92 bp.The average content of total GC was 38.9%.The chloroplast genome contains 132 specific genes,consisting of 85 coding genes,39 t RNA genes and 8 r RNA genes.2.The chloroplast genomes of Acidosasa and related genera are highly conserved in terms of gene number and sequence.The sequence variation of coding region was small,and the most variable was in the intergenic region.Compared with the relative genera,there are some differences in genes except IR and SC boundaries.Acidosasa and related genera formψndhh with incomplete replication in the IRb region..3.Based on complete chloroplast genome,the phylogenetic tree of the tribe Arundinarieae,including 11 Acidosasa species and 1 variety,was reconstructed,and showed that:1)the genus Acidosasa was not monophyletic,and the"three branches"taxa of the tribe Arundinarieae were highly clustered together;2)Acidosasa sp.1 had an independent system position,being sister to the extant acid bamboo species,and its characters were distinctive;3)Oligostachyum spongiosum was closely clustered with A.glauca,A.gigantea and A.notata(ML_BS=100%,PP=1.00),and its taxonomy should be revised.4.The micromorphological study of the abaxial leaf epidermis of Acidosasa and its related plants showed that papillae and their combinations with stomatal complexes were complex and should be divided into three types:Type I,no papillae around stomata（visible）;Type II,four long or short papillae surround,arch,or cover stomata,further divided into three groups according to the extent of stomata coverage,namely II-a,II-b and II-c;Type III,4-10 long or short papillae surround,arch,cover stomata,also divided into three groups,III-a,III-b and III-c.Combined with micro-hairs and silicon cells,the relatively stable patterns within the species have significant values to the taxonomy of"three-branched"group.Finally,based on literature,specimens,and above results,a new species—A.jiangxiensis W.G.Zhang&X.M.Li sp.nov.,a new combination—A.spongiosum（C.D.Chu&C.S.Chao）W.G.Zhang&X.M.Li comb.nov.,and a new variety—A.notata（Z.P.Wang&G.H.Ye）S.S.You’Hua’An 01’,have been found.