Interspecific hybrids (F1's) between Asian rice (Oryza sativa 2n=24 AA) and African rice (Oryza glaberrima 2n=24 AA) are almost completely sterile. This hybrid sterility barrier is mainly caused by an arrest of pollen development at the microspore stage. Intersubspecific F1 hybrid sterility is mainly caused by cryptic chromosomal aberrations and allelic interaction between indica and japonica. To identify O. glaberrima specific loci, 67 subspecies-specific (SS) sequenced-tagged site (STS) marker were used to evaluate 30 O. glaberrima accessions, which could be classified into sub eleven groups. SPI (subspecies-prototype index) of O. glaberrima accessions ranged from 51.67 to 60.00, suggesting intermediate subspecific type based on whole-genome. Some informative markers for classifying O. glaberrima accessions, called reference markers, S01054, S01160, S02085, S02140, S03041, and S08107, showed indica alleles, which might have contributed to genomic diversification of O. glaberrima. Ten (14.9%) SS markers generated glaberrima-specific alleles, implying loci adjacent with these markers could be a key for interspecific hybrid sterility. Only 40 (59.7%) SS markers might be useful in O. glaberrima analysis, as other markers did not amplify heterozygous alleles in F1 of O.sativa x O. glaberrima.
Key words: Subspecies-specific marker (SS), STS markers, indels, subspecies-prototype (SP), Oryza sativa, Oryza glaberrima.
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