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

Abstract

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.

Transcriptome shock in an interspecific F1 triploid hybrid of Oryza revealed by RNA sequencing

“…Oryza punctata is a wild species containing two cytoforms, i.e., diploid (genome BB, 2 n = 24) and tetraploid (genome BBCC, 2 n = 48), and is phylogenetically distant from cultivated Asian rice, O. sativa (genome AA, 2 n = 24). Nevertheless, recently both interspecific hybrid and allotetraploid plants between cultivated rice and the diploid cytoform of O. punctata (genome BB, 2 n = 24) were obtained and molecularly/cytogenetically characterized (Ishikawa et al ; Wang et al ). Here, we report successful inter‐ploidal hybridization and generation of a series of triploid F1 hybrid plants (genome ABC, 2 n = 36) between the laboratory standard cultivar (Nipponbare) of cultivated rice and the tetraploid cytoform of O. punctata (genome BBCC, 2 n = 48), which is an essential first step for assessing utility of this cytoform for rice improvement.…”

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

“…Hybrid plants were generated through embryo rescue according to the procedure described by Wang et al (2013). First backcross generations (BC 1 ) were generated using Sg99012-4X as a recurrent male parent.…”

“…From an evolutionary perspective, different genomic combinations and polyploidization reflects the general direction of crop evolution (Cai et al, 2001). Allopolyploids possess the evolutionary advantage of having double the genetic material for growth and adaptation and can overcome the reproductive barrier of wild and cultivated species (Wang et al, 2013). Hence, they may play an important role in the distant hybridization and assist plant breeders in the utilization of genetic resources from wild species.…”

“…It can also be used as a bridge for transferring desirable genes into cultivated rice through gene introgression (Cai et al, 2001). This study utilized the synthetic allopolyploid rice DCW008 (AABB) (created by our laboratory and reported by Wang et al 2013), which exhibits good fertility and advantageous agronomic traits. DCW008 was crossed and backcrossed with the high seed set tetraploid rice Sg99012-4X (AAAA) as a male parent to obtain the backcross derivatives.…”

Breeding and study of two new photoperiod- and thermo-sensitive genic male sterile lines of polyploid rice (Oryza sativa L.)

“…However, rice is diploid and has a small genome and DNA content relative to polyploid species, such as wheat. The demand for increased rice yield and quality is high, and the limited genetic resources of diploid cultivated rice have hampered improvements in hybrid rice breeding 11 . Therefore, new ways or methods are needed to address this dilemma.…”