Identification and Genetic Analysis of Collinearity Loci for Interspecific Hybrid Sterility in Genus Oryza.

Background: Hybrid sterility is a common phenomenon in hybrids between the Asian cultivated rice (Oryza sativa L.) and its relatives with AA genome, which limits the utilization of interspecific heterosis and favorable gene introgression. Numerous loci for hybrid sterility have been identified between O. sativa and its relatives. However, it remains elusive whether hybrid sterility between different species is controlled by a set of conserved loci, and whether there are variations in the genetic mode of these loci.

Results: In this study, six novel hybrid sterility loci for pollen sterility were identified from different cross combinations between O. sativa and its three wild relatives. S59 caused hybrid pollen sterility in hybrids between O. sativa and O. rufipogon. S60 and S61 controlled the hybrid pollen sterility between O. sativa and O. glumaepatula. S62, S63 and S64 governed the hybrid pollen sterility between O. sativa and O. barthii. Genetic and linkage analysis showed that S59, S60, and S62 were located in near the same region on the short arm of chromosome 5. S61 and S63 were mapped near RM27460 on the short arm of chromosome 12. S64 was restricted into the 60.27 kb region between RM4853 and RM3372 on the short arm of chromosome 3. The genetic behavior of six novel hybrid sterility loci follows one-locus allelic interaction model, the male gametes carrying the alleles of O. sativa in the heterozygotes were selectively aborted except for S62.

Conclusions: The findings from this research would provide a better understanding for the genetic nature of interspecific hybrid sterility in rice.