Oryza glumaepatula Steud. introgression lines in rice: identification of genes for reproductive barriers

摘要

To broaden rice genetic resources, we developed introgression lines carrying Oryza glumaepatufa (IRGC-Acc. 105668} and O. sativa cv, Taichung 65 cytoplasm. These lines contain overlapped O. glumaepatula chromosomal segments that covered most parts ofthe O. glumaepatula genome in the Taichung 65 genetic background, Introgression lines were developed through repeated backcrossing with Taichung 65 as a recurrent parent, Candidate lines were selected using 106 restriction fragment length polymorphism (RFLP) markers well distributed on 12 rice chromosomes. During the process of development, two reproductive barriers, hybrid weakness and pollen semisterility, were observed in the backcross populations. Hybrid weakness was attributed to the interaction between O. glumaepatula cytoplasm and the nuclear genome of Taichung 65. The dominant allele of O. glumaepatula restored the hybrid weakness of the plants having O. glumaepatula cytoplasm. The gene responsible for hybrid weakness restoration was designatedRhw (hybrid weakness restoration for O. glumaepatula cytoplasm) and was closely linked to RFLP marker C1115 on chromosome 8. Two F_1 pollen semisterility genes, S22(t) and S23(t), were closely linked to RFLP markers S910 on chromosome 2 and C1340 on chromosome 7, respectively. Since the O. glumaepatula homozygous alleles were not observed at the S910 locus in the BC_4F_2 population, it seemed that the pollen having the O. glumaepatula allele at the S22(t) locus aborted.