A General Polyploid Model for Analyzing Gene Segregation in Outcrossing Tetraploid Species

Corresponding author: Rongling Wu, Department of Statistics, 533 McCarty Hall C, University of Florida, Gainesville, FL 32611., rwu{at}stat.ufl.edu (E-mail)

Communicating editor: M. A. ASMUSSEN

Polyploidy has played an important role in higher plant evolution and applied plant breeding. Polyploids are commonly categorized as allopolyploids resulting from the increase of chromosome number through hybridization and subsequent chromosome doubling or autopolyploids due to chromosome doubling of the same genome. Allopolyploids undergo bivalent pairing at meiosis because only homologous chromosomes pair. For autopolyploids, however, all homologous chromosomes can pair at the same time so that multivalents and, therefore, double reductions are formed. In this article, we use a maximum-likelihood method to develop a general polyploid model for estimating gene segregation patterns from molecular markers in a full-sib family derived from an arbitrary polyploid combining meiotic behaviors of both bivalent and multivalent pairings. Two meiotic parameters, one describing the preference of homologous chromosome pairing (expressed as the preferential pairing factor) typical of allopolyploids and the other specifying the degree of double reduction of autopolyploids, are estimated. The type of molecular markers used can be fully informative vs. partially informative or dominant vs. codominant. Simulation studies show that our polyploid model is well suited to estimate the preferential pairing factor and the frequency of double reduction at meiosis, which should help to characterize gene segregation in the progeny of autopolyploids. The implications of this model for linkage mapping, population genetic studies, and polyploid classification are discussed.

This article has been cited by other articles:

				M. Stift, C. Berenos, P. Kuperus, and P. H. van Tienderen Segregation Models for Disomic, Tetrasomic and Intermediate Inheritance in Tetraploids: A General Procedure Applied to Rorippa (Yellow Cress) Microsatellite Data Genetics, August 1, 2008; 179(4): 2113 - 2123. [Abstract] [Full Text] [PDF]

				A.-B. Nyberg Berglund, A. Saura, and A. Westerbergh Electrophoretic Evidence for Disomic Inheritance and Allopolyploid Origin of the Octoploid Cerastium alpinum (Caryophyllaceae) J. Hered., May 1, 2006; 97(3): 296 - 302. [Abstract] [Full Text] [PDF]

				P. Catalan, J. G. Segarra-Moragues, M. Palop-Esteban, C. Moreno, and F. Gonzalez-Candelas A Bayesian Approach for Discriminating Among Alternative Inheritance Hypotheses in Plant Polyploids: The Allotetraploid Origin of Genus Borderea (Dioscoreaceae) Genetics, March 1, 2006; 172(3): 1939 - 1953. [Abstract] [Full Text] [PDF]

				J. P. Curole and D. Hedgecock Estimation of Preferential Pairing Rates in Second-Generation Autotetraploid Pacific Oysters (Crassostrea gigas) Genetics, October 1, 2005; 171(2): 855 - 859. [Abstract] [Full Text] [PDF]

				R. Wu and C.-X. Ma A General Framework for Statistical Linkage Analysis in Multivalent Tetraploids Genetics, June 1, 2005; 170(2): 899 - 907. [Abstract] [Full Text] [PDF]

				R. Wu, C.-X. Ma, and G. Casella A Bivalent Polyploid Model for Mapping Quantitative Trait Loci in Outcrossing Tetraploids Genetics, January 1, 2004; 166(1): 581 - 595. [Abstract] [Full Text] [PDF]

				C.-X. Ma, G. Casella, Z.-J. Shen, T. C. Osborn, and R. Wu A Unified Framework for Mapping Quantitative Trait Loci in Bivalent Tetraploids Using Single-dose Restriction Fragments: A Case Study from Alfalfa Genome Res., December 1, 2002; 12(12): 1974 - 1981. [Abstract] [Full Text] [PDF]