The Phylogentic Relationships Among Avena Species Based On The Sequences Of PsbA-trnH,Acc1and Pgk1, And Oat Glutenin Patterns

The genus of Avena L. belong to the tribe Aveneae, Poaceae, consists of29species. Clutivated oats as one of the most important crops in the world have been known for its high economic value in human nutrition and health. The genus Avena with many elite genetic resources is a very important gene pool for improving cultivated oats and related species. However, the species in this genus are often overlapping in distribution and morphologically in similar that it is very difficult to identify and classify. Thorough evaluation of the genetic resources, clear relationships among Avena species and reasonable classificational system are essential for maximum utilizing these germplam resources. In this study, based on the glutenin patterns, plastid intergenetic region psbA-trnH, single copy nuclear genes Accl and Pgkl, the relationships among Avena species and the evolution of polyploids of genus Avena were discussed. The main results are summaried as follows:1. Glutenin patterns of106accessions including23Avena taxa based on SDS-PAGE were investigated. A total of24glutenin bands and72glutenin patterns were detected. The hexaploids with ACD genomes and the diploids with A genome had the higher glutenin variations compared to the tetraploids with AB genomes, The tetraploids with AC genomes and the diploids with C genome had the percentage of polymorphism of85.7%and61.1%, respectively. These results indicated that the A genome had more variations. The clustering analysis showed that the majority accessions with identical genome constitutions or populations from one species could be clustered into one group at a given similarity coefficient. It suggested that the glutenin patterns could be used as fingerprint of genus Avena.2. Based on the maternal inheritance of chloroplast gene, the plastid intergenetic region psbA-trnH was sequenced to discuss the materal parents of the different polyploid species. MP tree showed all polyploids had been clutered with the diploids with A genome, suggesting that C genome as male parents participated in the evolution of polyploids. Most tetraploids with AB genome and the naked hexaploids with ACD genomes were clustered with the diploids with As genome. Most ACD genome hexaploids A. sativa clustered with populations from As genome diploids A. atlantica and Ac genome diploids A. canariensis. AC genome tetraploids and ACD genome hexploids A. occidentalis had a close relationship with Ai genome A. longiglumis and As genome diploids A. wiestii. These results indicated that several diploids with A genome were maternal parents involving in the evolution of different polyploids.3. Single copy nuclear genes Accl and Pgkl are widely utilized in the phylogenetic analysis. In this study, the partial sequences of Accl and Pgkl genes were obtained with the range from1529to1555bp, and1391to1523bp, respectively. The Accl gene sequences had8exons,7introns and1573alignment sites in which there were260variable characters with137parsimony-informative characters. The Pgkl gene sequences have5exons,4introns and1538alignment sites in which there were332variable characters with229parsimony informative characters.4. One of the main objectives in this study is to discuss the formation of polyploids of genus Avena. Based on the phylogenic analysis of psbA-trnH, Accl and Pgkl, the AB genome tetraploids A. barbata, A. abyssinica and A. vaviloviana had a close relationship with As genome diploids, suggesting that thes genome diploids might be the A gonome donar of these three AB genome tetraploids. In addition, another type of Accl gene sequences from the AB genome tetraploids A. barbata, A. abyssinica, A. vaviloviana were clustered into an independent clade, and it could not find any diploid species in this study which had a close relationship with those Accl gene sequences type. It is very noteworthy that the AB genome tetraploids A. agadiriana separated from the other AB genome tetraploids. Phylogenetic analysis of nuclear genes Accl and Pgkl indicated that A. agadiriana had close relationship with the Ac genome diploid species A.canariensis. Clustering analysis based on the glutenin patterns also got the similiar results. Analyses based on psbA-trnH sequences and glutenin patterns indicated that AC genome tetraploids had a close relationship with ACD genome hexaploids, indicating that AC tetraploids might be as a parent participated in the formation of ACD genome hexaploids.