Improving bridge effect to overcome interspecific hybrid sterility by pyramiding hybrid sterile loci from Oryza glaberrima

Abstract In order to evaluate the hybrid sterile effect and the bridging effect caused by the hybrid sterile locus, total nine NILs carrying one, two and three alleles of O. glaberrima were developed and used as test lines to cross with O. sativa and O. glaberrima accessions. The results showed that the degree of pollen sterility of F 1 hybrids between the NILs and Dianjingyou 1 has deepened with the increase of the number of alleles from O. glaberrima at the hybrid sterile loci. Under the action of three hybrid sterile loci, F 1 hybrids between the two cultivated rice species are almost completely sterile. On the other hand, the NILs carrying a single allele of O. glaberrima had limited effect on improving pollen fertility of interspecific hybrid. The pyramided lines containing multiple sterile alleles of O. glaberrima showed increased pollen fertility when crossing with O. glaberrima accessions. Further the backcrossing can be used to improve pollen and spikelet fertility of interspecific hybrids after the first cross. The report has potential for understanding the nature of interspecific hybrid sterility, and overcoming the interspecific hybrid F 1 pollen grain sterility between O. sativa and O. glaberrima .