Identification and characterization of Australian wild rice strains of Oryza meridionalis and Oryza rufipogon by SINE insertion polymorphism.

Of the rice species with an AA genome, Oryza meridionalis has been identified in northern Australia as a species of the annual type, among those previously classified as Oryza perennis, Oryza rufipogon or Oryza nivara. This notion has, however, led to some confusion to determine which strains belong to O. meridionalis and how different these strains are from the O. rufipogon strains of the annual type. In this paper, we examined Australian wild rice strains for the presence or absence of p-SINE1 members, which have been used for identification of the strains of species with the AA genome, by PCR using primers that hybridize to the sequences flanking each p-SINE1 member. The rice strains examined include perennial and annual strains, which have previously been described as O. rufipogon. We found that all the annual strains and other strains, whose types have not been determined, have p-SINE1 members that are specifically present at the corresponding loci in the standard strains of O. meridionalis, but do not have those which are specifically present at the corresponding loci in the strains of the other species with the AA genome. The perennial strains, however, have p-SINE1 members that are specifically present at the corresponding loci in the standard O. rufipogon strains of either the annual or the perennial type, but do not have those which are specifically present at the corresponding loci in the strains of the other species with the AA genome, including O. meridionalis. These findings support the previous notion that O. meridionalis consists of the annual strains and is a distinct species from O. rufipogon. The p-SINE1 members used in this study appear to be very useful for classification of any wild rice strains of the AA-genome species, even when one has limited knowledge of morphology, taxonomy, physiology, and biochemistry of rice strains.