Gene Expression In Ontogenetic Stages And Phylogenetic Relationships Of Representative Species Of Myxomycetes

Myxomycete (slime molds) is a widly distributed group, which is found in various environment, expecially in coot and wet forest. In cell genetics, physiology and biochemistry, and development of chemical composition, myxomycetes have important theoretical and applied value. Myxomycetes are always used as the model organism for cellular senescence and cancer. Because of the characteristic of its life circle, there is controversy over systematization of myxomycete. Because sporophore with spores likes fungi, and myxamoebae, swarm cells, plasmodia like protozoa, they were named as’Myxomycetes’and’Mycetozoa’ respectively.Here, discussed the characteristic of vegetative phase and reproducing phase and phylogeny relationship. That could provide a theoretical basis for reveal the origin and evolution of myxomycete.In this study, using moist chamber culture,54species were identified belong to22genus,7families,5orders. There were two new records in Inner Mongolia Hailar that Didymium megalosporum and Enerthenema papillatum. In moist chamber culture, the dominant family of Jilin Province and Inner Mongolia is Trichiaceae, and the dominant family of Qinling is Stemonitaceae.High quality RNA from sporophore and plasmodia were extracted by Trizol. Quantitative PCR was used to study the expression of CaM gene RNA in myxomycete sporophore and plasmodia period. The results showed that CaM gene RNA expressed throughout two stages, and the expression was relatively low in sporophore stage, high in plasmodia stage. Meanwhile, differential expression of CaM gene RNA from Physarella oblonga and Metatrichia vesparium may engender by artificial alimentation.Phylogenetic analysis of myxomycetes was investigated by partial SSU rRNA. EF-la and actin sequences amplified from19species (belonging to3orders) registered in Genbank. The accession numbers are JQ277908-JQ277932. Phylogenetic trees were constructed based on the maximum-likelihood and Bayes methods. The evolution trees showed that two clades:Trichiales, Physarales and Stemonitales. And based on phylogenetic trees, the result showed that evolution degree of Diachea leucopodia may be primitive, so that morphological characteristics of D. leucopodia looked alike Physarales and Stemonitales.For the genetic relationship within species of myxomycetes, Didymium squamulosum is an example of a cosmopolitan morphological species of myxomycete reported from numerous localities throughout the world. The molecular genetic relationships about D. Squamulosum from different geographically regions were analyzed based on SSU and5.8S rRNA sequences using Neighbor-joining method. From the molecular analysis result, genetic information of Didymium squamulosum from Alaska, New Zealand and Japan is not from one strain in same region. Because spores communicated by wind, and collection sites were not coherence. Ribosome sequences did not display arealvariation and migration completely.