A Preliminary Study On The Genes Of Myxosomal Protein And β - Tubulin

Myxomycetes are important and special group of eukaryotes. The taxonomic position of Myxomycetes in living nature was still controversy due to their life cycle which contain distinctly some features of both animal and fungus. Recently, they were phylogenetically included into one group of protozoa. However, Myxomycetes belonged to fungi or protozoa were always the task which taxonomist discussed. Aimed to set up a taxonomic system inclining to nature, the actin gene and β-tubulin gene from Myxomycetes have been amplified by PCR and sequenced in this paper. Systematic relation has been discussed by comparing and analyzing the sequence, and find more favorable evidences to solve this problem that Myxomycetes should belong to is difficult to determine using the morphological taxonomic methods, and was to establish the base to set up a taxonomic system inclining to nature.By pure culture of Didymium squamulosum and Stemonaria longa, we obtained their visible plasmodium. Consuming about the same quality of the fruiting body, extracted genomic DNA from plasmodium is a more effective method. When extracting genomic DNA from plasmodium, we obtained higher quality of the genomic DNA exclude outside pollution caused by human operation and there is no towing phenomenon, the DNA can be used directly in the subsequent PCR program. In a certain extent this approach can solve the problems that myxomycetes with less fruiting body and difficult to acquire as well as a new method to obtain higher quality of genomic DNA.In this study, using a pair of primer to amplify actin gene of seven samples and downloaded six actin gene sequences of Physarum polycephalum from GeneBank, constructed the phylogenetic tree based on the Maximum likelihood (ML) method. The phylogeny tree showed that the actin gene can effectively dividing the Liceales, Trichiales, Physarales and Stemonitales into two branches, one is the order Stemonitales displayed alone in a branch, the other is the Liceales, Trichiales and Physarales belonged to another branch.In this study, using a pair of primer to amplify β-tubulin gene of seven samples of Myxomycetes and downloaded two β-tubulin gene sequences of Physarum polycephalum from GeneBank, constructed the phylogenetic tree based on the Maximum likelihood (ML) method. The phylogeny tree showed that D.squamulosum (Physarales) and S.longa (Stemonitales) were cluster together at first, and then together with D. leucopodia (Physarales). It indicated that β-tubulin gene is not suitable for being a molecular marker of Myxomycetes.We deduced actin and β-tubulin amino acid sequences of seven myxomycetes. The differences of actin amino acid between species is about28%, about7%between β-tubulin amino acid sequences. It indicted that p-tubulin is more conserve than actin. The two proteins can distinguish plants, fungi, animals and protists in a better way. Phylogenetic tree constructed by actin amino acid suggested that myxomycetes are closer with fungi and animals, the results is consistent with the traditional classification of myxomycetes, but as to β-tubulin, the protein is so conserve that it doesnot reflect the relationship of myxomycetes.