Cytomorphological Characterization of the Backcross Progeny of Synthetic Amphiploid Rice (AABB) and Tetraploid Oryza sativa (AAAA)

Abstract

DCW008, a synthetic allopolyploid rice (2n = 4X = 48, AABB), was obtained from chromosome doubling of interspecific hybrids between Oryza sativa (2n = 24, AA) and O. punctata (2n = 24, BB). The F 1 and backcross (BC 1 ) hybrids were produced by crossing DCW008 as a female parent with a high seed set tetraploid rice Sg99012 -4X (2n = 4X = 48, AAAA). BC 1 F 1 and BC 1 F 2 overcame many of the wild-type traits of DCW008; they had yellow-hulled grains, seed set ranged from 0% to 71.31% and the grain morphology was similar to that of cultivated rice. Variable numbers of chromosomes were observed in pollen mother cells (PMCs) from the BC 1 plant. Genomic in situ hybridization (GISH) revealed that the majority of somatic cells and PMCs contained six chromosomes of O. punctata with fragment recombination observed in two of them. The backcross selection method employed in this study to generate allopolyploid progeny provides a reliable way of transferring useful genes from wild species into cultivated rice.

A New Way of Rice Breeding: Polyploid Rice Breeding

“…Tu et al made useful explorations in the use of autotetraploid three-line hybrid rice, and studied the methylation modification and Wx gene expression of autotetraploid rice [25][26][27][28]. Liu et al researched the reasons for the decrease of fertility and seed setting rate of autotetraploid rice through reproductive studies of autotetraploid rice and their interspecific hybrids [29][30][31][32]. Xing et al used a basic population of double embryo seedlings to screen out a batch of autopolyploid rice lines and crossed them with normal diploids for early-generation stable breeding [33,34].…”