Phylogenetic relationships among Oryza species revealed by AFLP markers

The genus Oryza to which cultivated rice belongs has 22 wild species. Seven ty-seven accessions of 23 Oryza species, five related genera, and three out group taxa were fingerprinted using amplified fragment length polymorphism (AFLP). A total of 1191 polymorphic markers were obtained using five AFLP p rimer combinations. AFLP data were analyzed to study species relationships using different clustering algorithms, and the resulting phenograms were te sted for stability and robustness. The findings suggest a common ancestry t o the genus Oryza. Moreover, the results demonstrate that: (1)evolution in Oryza has followed a polyphyletic path wherein multiple lineages underwent independent divergence after separation early in the evolution from a commo n ancestor/pool of related taxa; (2) newly assigned genomes, GG for O. meye riana and HHJJ for O. ridleyi complexes, are among the most diverged in the genus, (3) CCDD tetraploids have a relatively ancient origin among the Off icinalis complex; (4) O. malampuzhaensis, O. indandamanica, O. alta, and O. grandiglumis are diverged enough to deserve species status; (5) O. officin alis and O. eichingeri (CC) are putative progenitors of O. minuta/O. malamp uzhaensis and tetraploid O. punctata, respectively, (6) O. brachyantha is m ost diverged species in the genus. AFLP is reliable molecular technique and provides one of the most informative approaches to ascertain genetic relat ionships in Oryza, which may also be true for other related species/organis ms.