Abstract
Precise control of chromosome pairing is vital for conferring meiotic, and hence reproductive, stability in sexually reproducing polyploids. Apart from the Ph1 locus of wheat that suppresses homeologous pairing, little is known about the activity of genes that contribute to the cytological diploidization of allopolyploids. In oilseed rape (Brassica napus) haploids, the amount of chromosome pairing at metaphase I (MI) of meiosis varies depending on the varieties the haploids originate from. In this study, we combined a segregation analysis with a maximum-likelihood approach to demonstrate that this variation is genetically based and controlled mainly by a gene with a major effect. A total of 244 haploids were produced from F(1) hybrids between a high- and a low-pairing variety (at the haploid stage) and their meiotic behavior at MI was characterized. Likelihood-ratio statistics were used to demonstrate that the distribution of the number of univalents among these haploids was consistent with the segregation of a diallelic major gene, presumably in a background of polygenic variation. Our observations suggest that this gene, named PrBn, is different from Ph1 and could thus provide complementary information on the meiotic stabilization of chromosome pairing in allopolyploid species.
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Selected References
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- Masterson J. Stomatal size in fossil plants: evidence for polyploidy in majority of angiosperms. Science. 1994 Apr 15;264(5157):421–424. doi: 10.1126/science.264.5157.421. [DOI] [PubMed] [Google Scholar]
- Ozkan H., Feldman M. Genotypic variation in tetraploid wheat affecting homoeologous pairing in hybrids with Aegilops peregrina. Genome. 2001 Dec;44(6):1000–1006. [PubMed] [Google Scholar]
- Parkin I. A., Sharpe A. G., Keith D. J., Lydiate D. J. Identification of the A and C genomes of amphidiploid Brassica napus (oilseed rape). Genome. 1995 Dec;38(6):1122–1131. doi: 10.1139/g95-149. [DOI] [PubMed] [Google Scholar]
- Roberts M. A., Reader S. M., Dalgliesh C., Miller T. E., Foote T. N., Fish L. J., Snape J. W., Moore G. Induction and characterization of Ph1 wheat mutants. Genetics. 1999 Dec;153(4):1909–1918. doi: 10.1093/genetics/153.4.1909. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sharpe A. G., Parkin I. A., Keith D. J., Lydiate D. J. Frequent nonreciprocal translocations in the amphidiploid genome of oilseed rape (Brassica napus). Genome. 1995 Dec;38(6):1112–1121. doi: 10.1139/g95-148. [DOI] [PubMed] [Google Scholar]
- Shaw P., Moore G. Meiosis: vive la difference! Curr Opin Plant Biol. 1998 Dec;1(6):458–462. doi: 10.1016/s1369-5266(98)80035-6. [DOI] [PubMed] [Google Scholar]
- Sánchez-Morán E., Benavente E., Orellana J. Analysis of karyotypic stability of homoeologous-pairing (ph) mutants in allopolyploid wheats. Chromosoma. 2001 Sep;110(5):371–377. doi: 10.1007/s004120100156. [DOI] [PubMed] [Google Scholar]
- Wu R., Li B., Wu S. S., Casella G. A maximum likelihood-based method for mining major genes affecting a quantitative character. Biometrics. 2001 Sep;57(3):764–768. doi: 10.1111/j.0006-341x.2001.00764.x. [DOI] [PubMed] [Google Scholar]