Development and characterization of synthetic amphiploid (AABB) between Oryza sativa and Oryza punctata

Oryza punctata, a wild relative of cultivated rice, belongs to the BB genome of Oryza. Interspecific hybrids (CW008, AB) between Oryza sativa (2n = 24 AA) and O. punctata (2n = 24 BB) were obtained using embryo rescue technique. Synthetic allopolyploid (DCW008, AABB) were produced through chromosome doubling by colchicine. Hybrids overcame many wild traits except the shattering and awn. The synthetic amphiploid plants showed obvious superiority in growth and production. Interspecific hybrids CW008 were completely infertile but DCW008 had better seed set after selfing. Genomic in situ hybridization investigations were performed on DCW008. The result indicated that the A genome was closed to the B genome and translocations occurred between some chromosomes of cultivated and wild rice. Meiosis was nearly normal in the amphiploid hybrid but was disrupted in the diploid hybrid, which resulted in different fertility of them.