De4veropment of rRNA database for yeast type strains and multiple gene analysis for yeast taxonomy

本研究建立了酵母rRNA数据库，并对其作为rRNA基因信息的分类指标进行了评价。在此基础上，利用一个复合基因进行分子系统分析，试图为酵母分类的发展找到新的方法和新的概念，在许多分类群中，这些分子信息和分析可以在发现新的微生物的同时进行，能够收集多种类型酵母的rRNA基因信息。建立了酵母菌分子分类的开放式数据库，通过多基因分析发现，在所分析的所有属中，18S rDNA的替换率晚于26S rRNA D 1/D2结构域的替换率。在rRNA基因中存在一个突变丰富的位置和一个不存在突变的位置。结果表明，rRNA基因片段在属水平和种水平上均能较好地用于鉴定。有趣的是，26S rDNAD1/D2结构域在同一属内同源性是连续的，而18S rRNA基因的同源性是不连续的。特别是将毕赤酵母属的物种划分为多个系统发育类群，对酵母的分子系统进行了总结，提出了酵母分类的新概念。

In this research, production of the rRNA database of yeasts and evaluation as a classification index of rRNA gene information were performed. Furthermore, molecular systematic analysis using a multiplex gene is conducted, and it tried to find out the new method and new concept for developing the classification f yeasts.In many classification groups, those molecular information and analysis could be conducted simultaneously with discovery of a new microbe, and the rRNA gene information of many types of yeast was able to be collected. The open database of yeast molecular taxonomy was started to set up.Based on the multiple gene analysis, it was founded that the substitution rate of the 18S rDNA is late compared with the substitution rate of the 26S rRNA D 1/D2 domain in all of the analyzed genera. There are a position which is rich in mutation, and a position which is not so in rRNA gene. It seemed that the parts of the rRNA gene could be properly used as identification in a genus level and species level. Interestingly the continuity in the homology of 26S rDNA D1/D2 domain within the same genus was shown, but the discontinuity of 18S rRNA gene were found. Especially the species of genus Pichia were devided to several phylogenetic groups.We could summarize the molecular systematic of yeasts and proposed the new concepts of yeast classification.