The Study On Systematics Of Stigonema Ag.(Cyanobacteria)

Stigonema Ag. is a genera of cyanophyta, stigonematales, stigonemataceae, and also the only genera of stigonemataceae which reported in China, with complex true branch. Currently, there is a few results about the systematics of Stigonema Ag.. In this paper, we studyed systematically on the species of Stigonema Ag., the purpose is through comprehensive study of morphological and molecular, to further understand the Stigonema Ag., then explain the origin of it.The environmental samples of Stigonema Ag. were collected in Northeast China and North China, a total of1267samples. All the samples were observed under the microscope of the BX53, selected the samples which contain the species of Stigonema Ag., the Stigonema Ag. were photoed by micrograph, retention of digital photos. Described the species of the morphology in detail, compiled the morphological classification. At the same time, pure cultured of the selected Stigonema Ag. using the BG-11and CT culture medium. In order to provide the strain of pure cultured for research on molecular aspects, and to study the scope of more features.In order to determine the systematic location of Stigonema Ag. and the origin, we used the16S rRNA gene as target gene, PCR of the cultured strains and environmental strains. Ordinary PCR for the pure cultured Strain, and environmental samples with the whole-cell method for PCR. The products were cloned and sequenced, finally obtained the16srRNA gene sequences of14strains. Constructed NJ, MP tree of the obtained sequence using the software PAUP4.0, and analyzed the correlation of molecular systematics about those species. Then established the phylogenetic tree with the other species of Cyanophyta, illustrated the origin of Stigonema Ag..The results of morphology showed, there were Stigonema hormoides, Stigonema minutum, Stigonema minutum var. ramertaceum, Stigonema scytonematoides, Stigonema ocellatum, Stigonema lavardei, Stigonema aerugineum, Stigonema nanxionggensis, Stigonema turfaceum, Stigonema informe, Stigonema dendroidecum, Stigonema tomentosum and5Stigonema sp. in the Northeast and North China.The results of molecular showed that Stigonema Ag. was multiple origins.This study is not only an important help for the study on Stignema Ag., but also is significance to the study of prokaryotic evolution system.