XVI International Botanical Congess

Oryza L. includes about 20 wild and two cultivated species. Much work has been conducted on Oryza, but still there is considerable controversy about species relationship. We sequence the ITS regions of nuclear rDNA of 29 accessions representing 22 species of Oryza and four species of outgroups. The phylogenetic cladogram generated from parsimony analysis of ITS sequences shows four major clades, which are correspondent to four complexes. All species with AA genome make one clade, in which O. meriodonalis is relatively far from the other species. Species with BB, BBCC,CC,CCDD and EE gemones are in one clade,even though they show clear differentiation. In this clade, O. australiensis allied with all the other species loosely. The third clade supported by 100% bootstrap value contains O. ridleyi and O. longiglumis. This indicates that thay have close relationship. In the fourth clade, O, meyeriana is very closely related to O.granulata. O. brachyantha shows closer affinity with Poteresia coarctata, while O. schlechteri has close relationship with Leersia hexandra than with any other species in the genus Oryza.