Studies On Systematic Relationships Of Three Species Of Elymus In Australia And Genome Constitution Of Elymus Tenuis

Elymus L.is a very important genus in Triticeae Dumortier,with about 150 species. They are widely distributed in the temperate and subtropical regions of Asia,Europe, Australia,North America and South America.Many species of Elymus can be used as fodder crops.While enhancing the quality of cereal crops and pasture,Elymus has biological significance in the study of Triticeae evolution.Therefore,the study on classification and biological systems of Elymus species has an important theoretical and practical value.Since Elymus was established by Linnaean,this genus boundary of classification has been disputed considerably.Early plant taxonomists classified the species of Elymus based on morphological features.The dispute on Elymus definition revolves around whether the number of spikelet per spike as one of the key features of the classification criteria.Some taxonomists included the species with 2-4 spikelets per spike in Elymus,while the species with single spikelet were treated as other genus.But some scholars who defined Elymus more broadly,do not consider the number of spikelet per ear as a restriction.Therefore,the generic definition of Elymus has not yet to be in agreement.Yen et al.(2006) included the species of Elymus from Australia into Anthosachne.But most of their systematic relationships are still blurry.And the genome constitution of octploid Elymus tenuis is unavailable.In order to analyze the systematic relationships of three species of Elymus in Australia and the genome constitution of Elymus tenuis,Prof.Connor (University of Canterbury,New Zealand) carded out a lot of hybridizations and obtained interspecific hybrids among these species.In the present study,the chromosome pairs at MI of meiosis of pollen mother cells in these hybrids were observed and analyzed.The main results are as followed.1.E.scaber,E.multiflorus and E.solandri are all hexaploid species with the StYW genomes.There were average 20.28(17～21) bivalent in E.multiflorus~E,solandri.None multivalent was observed.In E.solandri×E.scaber,the average bivalent was 15.02(8～19). Multivalent were observed in some cells.The C-value of E.solandri×E.scaber was 0.52, which was much lower than that of E.multiflorus×E.solandri(0.86).So,E.multiflorus is much more closely related to E.solandri and the genome of E.scaber has an obvious variability.2.In genome analysis of hybrids E.multiflorus×E.tenuis,E.solandri×E.tenuis and Au.enysiix E.tenuis,bivalent of the three hybrids were close to 21,21 and 14.The C-values of them were 0.91,0.92,0.60,separately.Thus the genome constitution of E.tenuis is StYWH.