Gene segregation in autotetraploids: prediction from meiotic configurations

Jackson, R. C.; Jackson, Jeff W.

doi:10.1002/j.1537-2197.1996.tb12756.x

Cited by 29 publications

(27 citation statements)

References 36 publications

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“…There are several recent papers on this subject, both from a cytogenetic and a mathematical modelling point of view (Sybenga, 1994(Sybenga, , 1995(Sybenga, , 1996(Sybenga, , 1999Jackson and Jackson, 1996). The evidence suggests that these situations should be characterised by a general polyploid inheritance model with no complete preference to homologous or homeologous paring (Wu et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Estimation of allele frequencies in polyploids under certain patterns of inheritance

et al. 2005

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Allele frequencies have long been studied by biologists interested in evolution and speciation. More recently, with the application of molecular markers in human DNA profiling we have also seen the need for reliable population allele frequency estimates for making probabilistic inferences. There is now interest in applying the same DNA profiling technology to identification of plant varieties. HortResearch maintains a large germplasm of horticultural plant species. It is becoming evident that accurate identification of these accessions through DNA fingerprinting is essential for effective utilisation and maintenance of this germplasm. Microsatellites are the markers of choice for this fingerprinting. However, such markers do not reveal the dosage of alleles in a polyploid. Polyploidy is common amongst horticultural plants. Estimating allele frequencies in a polyploid population is, therefore, complicated because of some marker genotypes being phenotypically indistinguishable. For example, in a tetraploid, with four alleles at a locus showing polysomic inheritance, although 35 genotypes are possible, these will fall into only 15 marker phenotypic classes. Furthermore 'null' individuals are rarely detected in polyploids. Furthermore, some polyploids can be cryptic exhibiting disomy, instead of the polysomic inheritance. We will discuss the implications of these factors and present an EM-type algorithm for estimating allele frequencies of a polyploid population under certain patterns of inheritance. The method will be demonstrated on simulated data. We also discuss the nature of some of the additional problems that may be encountered with estimating allele frequencies in polyploids for which other solutions still need to be developed. Heredity (2005) 95, 327-334.

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Section: Introductionmentioning

confidence: 99%

Estimation of allele frequencies in polyploids under certain patterns of inheritance

et al. 2005

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“…Specifically, autopolyploids may undergo either bivalent pairing (two homologs pair) or multivalent pairing (more than two homologues pair), and it varies in different species (Rieseberg and Doyle 1989;Sybenga 1995). Furthermore, the manner in which the paired chromosomes segregate during meiosis, especially for multivalent pairing, also varies among species (Jackson and Jackson 1996). Finally, the number of alleles for each locus, how many copies of each allele, and the linkage phase between loci for the parents and the progeny are unknown.…”

Section: Introductionmentioning

confidence: 99%

Interval Mapping for Autopolyploids

Cao¹,

Craig²,

Doerge³

2003

Conference on Applied Statistics in Agriculture

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While extensive progress has been made in quantitative trait locus (QTL) mapping of diploid species, the progress of QTL mapping in polyploids has been limited due to the polyploid's complex genetic architecture. To date, QTL mapping in polyploids has focused primarily on tetraploids with dominant markers and/or codominant markers. In this paper, we extend the interval mapping methodology to any autopolyploid of even ploidy level. Our approach selects a set of likely parental chromosomal configurations (models) using a Bayesian model reduction step. The EM algorithm is then employed to estimate each model's parameters including QTL location, marker dosages, QTL dosages, and the trait effect.

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“…Polyploids have been classified as either autopolyploids, originated from genetically similar genomes, or allopolyploids with chromosome combination derived from distinct (interspecific) genomes (3,6). However, the terms disomic polyploids and polysomic polyploids better describe the nature of polyploids from the viewpoint of both genetics and breeding (7).…”

mentioning

confidence: 99%

“…Disomic polyploids have bivalent chromosome pairing between strictly homologous chromosomes and a diploid-like genetic behavior (allopolyploids are generally disomic) (7). However, many polyploid taxa represent intermediate stages between these two extremes (3,6).…”

mentioning

confidence: 99%

Selection–mutation balance in polysomic tetraploids: Impact of double reduction and gametophytic selection on the frequency and subchromosomal localization of deleterious mutations

Butruille

Boiteux

2000

Proc. Natl. Acad. Sci. U.S.A.

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We modeled the behavior of recessive mutations with deleterious effects to either the sporophyte or the gametophyte, or both, in polysomic tetraploid populations by allowing for varying levels of double reduction, mutation, and self-fertilization. Double reduction causes a decrease of the equilibrium frequencies of deleterious alleles, and it has much more influence on genes subjected to gametophytic selection than on genes solely under sporophytic selection. With gametophytic selection, low frequencies of double reduction are enough to reduce equilibrium frequencies severalfold. Double reduction occurs when sister alleles migrate to the same gamete during meiosis. It depends on the frequency at which a locus recombines with its centromere, and on the frequency of multivalent formation. Therefore, a greater accumulation of deleterious mutations should occur on polysomic chromosomes with a prevalence of bivalent pairing and in chromosomal regions between centromeres and proximal chiasmata. Proximal loci should have a greater impact in reducing the fitness of a polyploid population being inbred. This prediction can explain observations that homozygosities at different subchromosomal regions have distinct effects on inbreeding depression in polyploids. Furthermore, even mildly deleterious alleles can lead to large amounts of inbreeding depression because of their high equilibrium frequencies. Molecular studies correlating level of heterozygosity and degree of heterosis should take into account this nonuniform distribution of deleterious alleles in polyploid genomes. Preservation or enhancement of heterozygosity would be more critical at proximal regions than at other chromosome regions in polysomic polyploid species.

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Gene segregation in autotetraploids: prediction from meiotic configurations

Abstract: Physiology and BiochemistrySinapate esters provide greater UV-B attenuation than f1avonoids in Arabidopsis thaliana (Brassicaceae) JOHN J. SHEAHAN 679

Cited by 29 publications

References 36 publications

Estimation of allele frequencies in polyploids under certain patterns of inheritance

Estimation of allele frequencies in polyploids under certain patterns of inheritance

Interval Mapping for Autopolyploids

Selection–mutation balance in polysomic tetraploids: Impact of double reduction and gametophytic selection on the frequency and subchromosomal localization of deleterious mutations

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