Origin And Evolvement Of Aster Ageratoides Vai. Gerlachii

Hce established the Aster ageratoides var gerlachii in1880and placed it in Aster L.(Asterinae, Astereae, Asteraceae). Its distribution center is south of China in Hunan and Hubei province. It extends southwest to Guizhou province and extends northwest to Shan’xi province. Although a small number of previous studies have shown that it comes from Aster ageratoides, only a few species of Aster ageratoides var. gerlachii have been included or so little molecular markers were considered in previous analyses especially in different varieties and populations. Therefore to make the thorough and meticulous revision is very necessary and meaningful.In the present study, through reviewing herbarium specimens, observing leaf epidermis stomatals, karyotype analysis and molecular systermatics study, we will understand the origin and evolution of Aster ageratoides var gerlachii. According to such research, we preliminarily detemines its female parent is Aster ageratoides, its male parent is Aster homochlamydeus Hand-Mazz in Lixian. The relationship of Aster ageratoides var gerlachii should be that two octaploid groups are developed from tetraploid communities, but the two tetraploid population who are more primitive is not very clear.1、Morphological studiesAccording to on all specimens of Aster ageratoides var gerlachii different population were different in size of leaves, indumentum and other characters.We found that these characters were quite variable.It’s a pity that we haven’t interpreted the origin and evolution of the relationship between Aster ageratoides car gerlachii. This finding was of low to moderate significance.On the leaf epidermis micro morphology, the epidermal cells of Aster ageratoides var gerlachii in Liping were similar to Aster ageratoides var gerlachii in Hupingshan. We can guess that Aster ageratoides var gerlachii in Hupingshan is evolving from Aster ageratoides var gerlachii in Liping. The epidermis stomatal apparatus cells of Aster ageratoides var gerlachii in Shennongjia belong to the normal and the epidermis stomatal apparatus cells of other three groups have two types. Maybe the three other groups developed from Aster ageratoides var gerlachii in Shennongjia.2、Cytological researchThe results of cytological observations relieved that its basic number of somatic chromosome is9,they are tetraploid with36chromosomes and octaploid with72chromosomes. Aster ageratoides var gerlachii in Shennongjia and Liping are tetraploid. While Aster ageratoides var gerlachii in Baijin and Hupingshan are octaploid. In addition, two octaploid communities of chromosome karyotype asymmetry coefficient is higher than any other two tetraploid groups. All mentioned above supported that octaploid groups were came from or evolved from the more primitive tetraploid population. The chromosome data and karyotypes of Aster ageratoides var gerlachii are reported for the first time.3、Molecular systematicsBy reconstruction of a phylogenetic tree, the origin and evolution of Aster ageratoides var gerlachii was studied. We know Aster ageratoides var gerlachii is heterozygous. His male parent is Aster homochlamydeus Hand-Mazz, his female parent is Aster ageratoides. In tetraploid population, there is asynchronism in evolution of ITS sequence, that is to say, the same clone individuals tend to male parent in ITS1sequences. While ITS2sequence tends to be the female parent. Through sequences analysis in comparision with each other, it is obvious that concerted evolution in tetraploidpopulation have not complectly finished.On the contrary, the concerted evolution in octaploid are complectly finished and all populations are partial to male parent.In general the more somatic chromosomes they are the more completely concerted evolution they will be.In addition to,through SBP cloning results from four diploid individuals, we can be determined that SBP sequence is low copy sequence, rather than a single copy in Aster ageratoides. The molecular biology information about Aster ageratoides var gerlachii all are reported for the first time.