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 F1 and backcross (BC1) hybrids were produced by crossing DCW008 as a female parent with a high seed set tetraploid rice Sg99012 - 4X (2n = 4X = 48, AAAA). BC1F1 and BC1F2 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 BC1 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.
Highlights
The genus Oryza is composed of more than 20 species, represented cytogenetically by ten genome groups, including two cultivated species, O. sativa L. and O. glaberrima Steud (Li et al, 2001; Bao et al, 2006)
BC1F1 and BC1F2 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
Abundant wild species of Oryza provide extremely valuable genetic resources to broaden the genetic background of cultivated rice (Khush, 1977)
Summary
The genus Oryza is composed of more than 20 species, represented cytogenetically by ten genome groups, including two cultivated species, O. sativa L. and O. glaberrima Steud (Li et al, 2001; Bao et al, 2006). Allopolyploids, which have multiple chromosome sets, exhibit high plasticity since they have the evolutionary advantage of possessing additional genetic materials for growth and adaptation. They may play an important role in the distant hybridization and promote the exploitation of useful genes from wild species. Allopolyploid rice is a versatile material that can be used to study relationships between different genome groups or in research on rice evolution It can be used as a bridge for transferring desirable genes into cultivated rice through gene introgression (Cai et al, 2001). Grain yield and other major agronomic traits of F1, BC1F1 and BC1F2 were investigated
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