QTL analysis for hybrid sterility and plant height in interspecific populations derived from a wild rice relative, Oryza longistaminata

Hybrid sterility is a serious barrier in the utilization of wild rice for breeding, but little is known regarding hybrid sterility between the cultivated rice, Oryza sativa, and its wild relative, O. longistaminata. In order to understand further the nature of interspecific hybrid sterility, pollen and spikelet fertility were investigated in two BCsub(7)Fsub(2) populations derived from a semisterile individual of BCsub(5)Fsub(1) between Oryza sativa L. and O. longistaminata. One main-effect QTL for pollen and spikelet fertility qpsf6 was detected on the short arm of chromosome 6 close to RM587, around it favoring O. longistaminata allele was found. Comparing the position and effect with other studies indicated that this QTL coincides with the gamete eliminator, S1. It suggests that there exists an orthologous hybrid sterility locus that controls the reproduction barrier between O. sativa and its AA genome relatives. QTL mapping for plant height was also conducted in one of the BCsub(7)Fsub(2) populations. One QTL, qph1, was detected on the long arm of chromosomes 1 close to RM6333 and coincides with the semi-dwarf gene, sd-1. These new QTL information will increase the efficiency of cultivar development via interspecific hybridization involving O. longistaminata, and offset the stage for fine mapping of these QTL.