Dataset Information

Multiple origins of BBCC allopolyploid species in the rice genus (Oryza).

ABSTRACT: In the rice genus (Oryza), about one half of the species are allopolyploids. These species are not only important resources for rice breeding but also provide a unique opportunity for studying evolution of polyploid species. In the present study, we sequenced four biparentally inherited nuclear loci and three maternally inherited chloroplast fragments from all diploid and tetraploid species with the B- and C-genome types in this genus. We detected at least three independent origins of three BC-genome tetraploid species. Specifically, the diploid O. punctata (B-genome) and O. officinalis (C-genome) were the parental progenitors of O. minuta and O. malampuzhaensis with O. punctata being the maternal donors, whereas the diploid O. punctata and O. eichingeri (C-genome) were the progenitors of tetraploid O. punctata with O. punctata being the paternal donor. Our relaxed clock analyses suggest that all the BBCC species originated within the last one million years, which is coincident with the severe climate oscillations occurred during the last ice age, implying the potential impact of climate change on their formations and dispersals. In addition, our results support previous taxonomic arguments that the tetraploid O. punctata might be better treated as a separate species (O. schweinfurthiana).

SUBMITTER: Zou XH

PROVIDER: S-EPMC4602239 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Multiple origins of BBCC allopolyploid species in the rice genus (Oryza).

Zou Xin-Hui XH Du Yu-Su YS Tang Liang L Xu Xin-Wei XW Doyle Jeff J JJ Sang Tao T Ge Song S

Scientific reports 20151013

In the rice genus (Oryza), about one half of the species are allopolyploids. These species are not only important resources for rice breeding but also provide a unique opportunity for studying evolution of polyploid species. In the present study, we sequenced four biparentally inherited nuclear loci and three maternally inherited chloroplast fragments from all diploid and tetraploid species with the B- and C-genome types in this genus. We detected at least three independent origins of three BC-g ...[more]

PMID: 26460928

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Project description:BackgroundThe total protein contents of rice seeds are significantly higher in the three wild rice species (Oryza rufipogon Grill., Oryza officinalis Wall. and Oryza meyeriana Baill.) than in the cultivated rice (Oryza sativa L.). However, there is still no report regarding a systematic proteomic analysis of seed proteins in the wild rice species. Also, the relationship between the contents of seed total proteins and rice nutritional quality has not been thoroughly investigated.ResultsThe total seed protein contents, especially the glutelin contents, of the three wild rice species were higher than those of the two cultivated rice materials. Based on the protein banding patterns of SDS-PAGE, O. rufipogon was similar to the two cultivated rice materials, followed by O. officinalis, while O. meyeriana exhibited notable differences. Interestingly, O. meyeriana had high contents of glutelin and low contents of prolamine, and lacked 26 kDa globulin band and appeared a new 28 kDa protein band. However, for O. officinali a 16 kDa protein band was absent and a row of unique 32 kDa proteins appeared. In addition, we found that 13 kDa prolamine band disappeared while special 14 kDa and 12 kDa protein bands were present in O. officinalis. Two-dimensional gel electrophoresis (2-DE) analysis revealed remarkable differences in protein profiles of the wild rice species and the two cultivated rice materials. Also, the numbers of detected protein spots of the three wild rice species were significantly higher than those of two cultivated rice. A total of 35 differential protein spots were found for glutelin acidic subunits, glutelin precursors and glutelin basic subunits in wild rice species. Among those, 18 protein spots were specific and 17 major spots were elevated. Six differential protein spots for glutelin acidic subunits were identified, including a glutelin type-A 2 precursor and five hypothetical proteins.ConclusionThis was the first report on proteomic analysis of the three wild rice species. Overall results suggest that there were many new types of glutelin subunits and precursor in the three wild rice species. Hence, wild rice species are important genetic resources for improving nutritional quality to rice.

Project description:BackgroundInter-specific hybridization occurs frequently in higher plants, and represents a driving force of evolution and speciation. Inter-specific hybridization often induces genetic and epigenetic instabilities in the resultant homoploid hybrids or allopolyploids, a phenomenon known as genome shock. Although genetic and epigenetic consequences of hybridizations between rice subspecies (e.g., japonica and indica) and closely related species sharing the same AA genome have been extensively investigated, those of inter-specific hybridizations between more remote species with different genomes in the rice genus, Oryza, remain largely unknown.Methodology/principal findingsWe investigated the immediate chromosomal and molecular genetic/epigenetic instability of three triploid F1 hybrids produced by inter-specific crossing between species with divergent genomes of Oryza by genomic in situ hybridization (GISH) and molecular marker analysis. Transcriptional and transpositional activity of several transposable elements (TEs) and methylation stability of their flanking regions were also assessed. We made the following principle findings: (i) all three triploid hybrids are stable in both chromosome number and gross structure; (ii) stochastic changes in both DNA sequence and methylation occurred in individual plants of all three triploid hybrids, but in general methylation changes occurred at lower frequencies than genetic changes; (iii) alteration in DNA methylation occurred to a greater extent in genomic loci flanking potentially active TEs than in randomly sampled loci; (iv) transcriptional activation of several TEs commonly occurred in all three hybrids but transpositional events were detected in a genetic context-dependent manner.Conclusions/significanceArtificially constructed inter-specific hybrids of remotely related species with divergent genomes in genus Oryza are chromosomally stable but show immediate and highly stochastic genetic and epigenetic instabilities at the molecular level. These novel hybrids might provide a rich resource of genetic and epigenetic diversities for potential utilization in rice genetic improvements.

Dataset Information

Multiple origins of BBCC allopolyploid species in the rice genus (Oryza).

Publications

Multiple origins of BBCC allopolyploid species in the rice genus (Oryza).

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