Genetic significance of mode of polyploidization: somatic doubling or 2n gametes?

Genome ◽  
1991 ◽  
Vol 34 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Kazuo Watanabe ◽  
Stanley J. Peloquin ◽  
Masatoshi Endo
Keyword(s):  
Combining Ability ◽  
Allelic Diversity ◽  
2N Gametes ◽  
Genotypic Diversity ◽  
P Value ◽  
Sexual Polyploidization ◽  
Gamete Formation ◽  
Single Exchange ◽  
Genetic Significance ◽  
2N Gamete

Computer simulation was undertaken to compare the genetic consequences of asexual (somatic doubling) and sexual (2n gametes) polyploidization. The coefficient of inbreeding at a locus, the number and frequency of genotypes at a locus, and the proportion of tri- and tetra-allelic genotypes were considered. The factors considered to estimate the genetic consequences were (i) mechanisms of sexual polyploidization, by first division restitution (FDR) × second division restitution (SDR), FDR × FDR, or SDR × SDR; (ii) position of the locus in relation to the centromere, which affects the gametic output in 2n gamete formation and thus the probability of single-exchange tetrads in meiosis during 2n gamete formation (p value); and (iii) allelic diversity at a locus. In comparing asexual and sexual polyploidization, regardless of the position of a locus in relation to the centromere, sexual polyploidization generally indicated less inbreeding, more genotypic diversity, and a higher proportion of tri- and tetra-allelic genotypes. When allelic diversity at a locus was increased, these characteristics were even more prominent. When only two alleles are possible at a locus, somatic doubling would not be inferior to sexual polyploidization. Overall results favored SDR × FDR and FDR × FDR as a mode and mechanisms of polyploidization. The genetic variations produced by 2n gametes could be attributed to "combining ability of 2n gametes."Key words: asexual polyploidization, sexual polyploidization, inbreeding, heterozygosity, combining ability of 2n gametes.

The Role of 2n Gametes and Endosperm Balance Number in the Origin and Evolution of Polyploids in the Tuber-Bearing Solanums

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 287-294 ◽  
Author(s):  
Domenico Carputo ◽  
Luigi Frusciante ◽  
Stanley J Peloquin
Keyword(s):  
Parental Species ◽  
2N Gametes ◽  
Solanum Species ◽  
Endosperm Balance Number ◽  
Sexual Polyploidization ◽  
Ancestral Species ◽  
Origin And Evolution ◽  
Bilateral Sexual Polyploidization ◽  
2N Gamete

Abstract Polyploidization has played a major role in the origin and evolution of polyploid species. In this article we outline the unique characteristics of 2n gametes and implications of their participation in the evolution of polyploid Solanum species. The genetic consequences of 2n gametes indicate that sexual polyploidization results in greater variability, fitness, and heterozygosity than does somatic doubling. Further, the mechanisms of 2n gamete formation and the frequency of 2n gamete-forming genes in present polyploids and their ancestral species provide additional evidence of their involvement. Equally important is the endosperm, via the endosperm balance number (EBN) incompatibility system, in complementing the role of 2n gametes. In fact, the EBN system acts as a screen for either 1n or 2n gametes, depending on the EBN and chromosome numbers of parental species. EBN in combination with 2n gametes maintains the ploidy integrity of diploid ancestral species, while providing the flexibility for either unilateral or bilateral sexual polyploidization.

scholarly journals Genomics-based discrimination of 2n gamete formation mechanisms in polyploids: a case study in nonaploid Diospyros kaki ‘Akiou’

2021 ◽  
Author(s):  
Peng Sun ◽  
Soichiro Nishiyama ◽  
Hideaki Asakuma ◽  
Roeland E Voorrips ◽  
Jianmin Fu ◽  
...  
Keyword(s):  
2N Gametes ◽  
Unreduced Gametes ◽  
Formation Mechanisms ◽  
Common Source ◽  
Diospyros Kaki ◽  
Normal Female ◽  
Gamete Formation ◽  
Allele Dosage ◽  
2N Gamete ◽  
Gamete Production

Abstract Unreduced gametes (2n gametes), possessing double the haploid genome, whatever ploidy that happens to be, are a common source of ploidy variation in plant populations. First and second division restitution (FDR and SDR) are the dominant mechanisms of 2n gamete production; all else being equal, FDR gametes have a higher degree of heterozygosity, thus they are advantageous in breeding. The discrimination of these mechanisms from the consequence of hybridization is challenging, especially in higher polyploids, and usually requires information on centromere location. In this study, we propose a genotyping-based strategy to uncover the mechanisms of 2n gamete formation in progeny that has a higher ploidy than its parents. Simulation of 2n gamete production revealed that FDR and SDR pathways can be discriminated based on allele transmission patterns alone without information on centromere location. We applied this strategy to study the formation mechanism of a nonaploid Diospyros kaki ‘Akiou’, which was bred via hybridization between D. kaki hexaploid cultivars. The result demonstrated that ‘Akiou’ was derived from the fertilization of a normal female gamete by a 2n male gamete, and that this 2n gamete was produced through FDR. Consequently, the distinct duplex transmission pattern in the FDR gamete enabled us to infer the genomic characteristics of polyploid persimmon. The method could be tested only for the plant being polypoid, which allows for the ability to discriminate causes of 2n gamete formation using allele dosage in progeny, and will be useful in future studies of polyploid genomics.

scholarly journals Nature of 2n Gamete Formation and Mode of Inheritance in Interspecific Hybrids of Diploid Vaccinium darrowii and Tetraploid V. corymbosum

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 808E-808
Author(s):  
Luping Qu ◽  
J.F. Hancock
Keyword(s):  
Interspecific Hybrids ◽  
Rapd Markers ◽  
2N Gametes ◽  
Diploid Population ◽  
A Value ◽  
Tetraploid Hybrid ◽  
Gamete Formation ◽  
2N Gamete ◽  
Segregating Population ◽  
Mode Of Inheritance

RAPD markers were used to determine the level of heterozygosity transmitted via 2n gametes from V. darrowi cv. Florida 4b (Fla 4B) to interspecific hybrids with tetraploid V. corymbosum cv. Bluecrop. The tetraploid hybrid US 75 was found to contain 70.6% of Fla 4B's heterozygosity, a value consistent with a first division restitution (FDR) mode of 2n gamete production. Crossovers during 2n gamete formation were evidenced by the absence of 16 dominant alleles of Fla 4B in US 75, and direct tests of segregation in a diploid population involving Fla 4B. RAPD markers that were present in both Fla 4B and US 75 were used to determine the mode of inheritance in a segregating population of US 75 × V. corymbosum cv. Bluetta. More than 30 homozygous pairs of alleles were located that segregated in a 5:1 ratio, indicating US 75 undergoes tetrasomic inheritance.

scholarly journals Sorghum bicolor x S. halepense interspecific hybridization is influenced by the frequency of 2n gametes in S. bicolor

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
George L. Hodnett ◽  
Sara Ohadi ◽  
N. Ace Pugh ◽  
Muthukumar V. Bagavathiannan ◽  
William L. Rooney
Keyword(s):  
Gene Flow ◽  
Sorghum Bicolor ◽  
Interspecific Hybridization ◽  
2N Gametes ◽  
Female Parent ◽  
Optimum Conditions ◽  
Male Sterile ◽  
Chemically Induced ◽  
Parent Selection ◽  
2N Gamete

AbstractTetraploid johnsongrass [Sorghum halepense (L.) Pers.] is a sexually-compatible weedy relative of diploid sorghum [Sorghum bicolor (L.) Moench]. To determine the extent of interspecific hybridization between male sterile grain sorghum and johnsongrass and the ploidy of their progeny, cytoplasmic (CMS), genetic (GMS) and chemically induced male sterile lines of Tx623 and Tx631 were pollinated with johnsongrass pollen. At maturity 1% and 0.07% of the developing seeds of Tx623 and Tx631 respectively were recovered. Ninety-one percent of recovered hybrids were tetraploid and two percent were triploid, the tetraploids resulting from 2n gametes present in the sorghum female parent. Their formation appears to be genotype dependent as more tetraploids were recovered from Tx623 than Tx631. Because a tetraploid sorghum x johnsongrass hybrid has a balanced genome, they are male and female fertile providing opportunities for gene flow between the two species. Given the differences in 2n gamete formation among Tx623 and Tx631, seed parent selection may be one way of reducing the likelihood of gene flow. These studies were conducted in controlled and optimum conditions; the actual outcrossing rate in natural conditions is expected to be much lower. More studies are needed to assess the rates of hybridization, fitness, and fertility of the progeny under field conditions.

scholarly journals Genotypic Diversity and Resistance to Azoxystrobin of Cercospora beticola on Processing Table Beet in New York

Plant Disease ◽  
2016 ◽  
Vol 100 (7) ◽  
pp. 1466-1473 ◽  
Author(s):  
Niloofar Vaghefi ◽  
Frank S. Hay ◽  
Julie R. Kikkert ◽  
Sarah J. Pethybridge
Keyword(s):  
New York ◽  
Spore Germination ◽  
Microsatellite Loci ◽  
Point Mutations ◽  
Allelic Diversity ◽  
Genotypic Diversity ◽  
Cercospora Beticola ◽  
Mating Types ◽  
Cercospora Leaf Spot ◽  
Quinone Outside Inhibitor

Cercospora leaf spot (CLS), caused by Cercospora beticola, is one of the major diseases affecting productivity and profitability of beet production worldwide. Fungicides are critical for the control of this disease and one of the most commonly used products is the quinone outside inhibitor (QOI) azoxystrobin. In total, 150 C. beticola isolates were collected from two commercial processing table beet fields in Batavia, NY in 2014. The mating types of the entire population were determined, and genetic diversity of a subset of samples (n = 48) was assessed using five microsatellite loci. Sensitivity to azoxystrobin was tested using a spore germination assay. The cytochrome b gene was sequenced to check for the presence of point mutations known to confer QOI resistance in fungi. High allelic diversity (He = 0.50) and genotypic diversity (D* = 0.96), gametic equilibrium of the microsatellite loci, and equal ratios of mating types were suggestive of a mixed mode of reproduction for C. beticola. Resistance to azoxystrobin was prevalent because 41% of the isolates had values for effective concentrations reducing spore germination by 50% (EC50) > 0.2 μg/ml. The G143A mutation, known to cause QOI resistance in C. beticola, was found in isolates with EC50 values between 0.207 and 19.397 μg/ml. A single isolate with an EC50 of 0.272 μg/ml carried the F129L mutation, known to be associated with low levels of QOI resistance in fungi. This is the first report of the F129L mutation in C. beticola. The implications of these findings for the epidemiology and control of CLS in table beet fields in New York are discussed.

scholarly journals Genetic Diversity and Differentiation inPhoma betaePopulations on Table Beet in New York and Washington States

Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1487-1497 ◽  
Author(s):  
Lori B. Koenick ◽  
Niloofar Vaghefi ◽  
Noel L. Knight ◽  
Lindsey J. du Toit ◽  
Sarah J. Pethybridge
Keyword(s):  
Genetic Diversity ◽  
New York ◽  
Mating Type ◽  
Gene Diversity ◽  
Management Strategies ◽  
Allelic Diversity ◽  
Genotypic Diversity ◽  
Reproduction Mode ◽  
Inoculum Source ◽  
Seed Crops

Phoma betae is an important seedborne pathogen of table beet worldwide that is capable of causing foliar, root, and damping-off diseases. Ten microsatellite and mating type markers were developed to investigate the genetics of P. betae populations in table beet root crops in New York and in table beet seed crops in Washington, from where table beet seed is predominantly sourced. The markers were used to characterize 175 isolates comprising five P. betae populations (two from New York and three from Washington), and they were highly polymorphic with an allelic range of 4 to 33 and an average of 11.7 alleles per locus. All populations had high genotypic diversity (Simpson’s complement index = 0.857 to 0.924) and moderate allelic diversity (Nei’s unbiased gene diversity = 0.582 to 0.653). Greater differentiation observed between populations from the two states compared with populations within the same state suggested that an external inoculum source, such as windblown ascospores, may be homogenizing the populations. However, most genetic diversity (87%) was among individual isolates within populations (pairwise index of population differentiation = 0.127; P = 0.001), suggesting that local within-field inoculum source(s), such as infested field debris or infected weeds, may also be important in initiating disease outbreaks. Standardized index of association, proportion of compatible pairs of loci, and mating type ratio calculations showed evidence for a mixed reproduction mode in all populations. These findings could be useful in designing more effective management strategies for diseases caused by P. betae in table beet production.

scholarly journals 2n Gamete formation in the genus Brachiaria (Poaceae: Paniceae)

Euphytica ◽  
2006 ◽  
Vol 154 (1-2) ◽  
pp. 255-260 ◽  
Author(s):  
Patrícia Helena Gallo ◽  
Pamela Lonardoni Micheletti ◽  
Kellen Regina Boldrini ◽  
Claudicéia Risso-Pascotto ◽  
Maria Suely Pagliarini ◽  
...  
Keyword(s):  
Gamete Formation ◽  
2N Gamete

scholarly journals Fertility of Triploid Highbush Blueberry

1991 ◽  
Vol 116 (2) ◽  
pp. 336-341 ◽  
Author(s):  
N. Vorsa ◽  
James R. Ballington
Keyword(s):  
Gene Transfer ◽  
Chromosome Number ◽  
Chromosome Numbers ◽  
2N Gametes ◽  
Basic Chromosome Number ◽  
Highbush Blueberry ◽  
Pollen Stainability ◽  
Frequency Distributions ◽  
Basic Chromosome ◽  
2N Gamete

Eight highbush blueberry (V. corymbosum L.) triploids (2n = 3x = 36) were crossed with diploids (2n = 2x = 24), tetraploids (2n = 4x = 48), and hexaploids (2n = 6x = 72). No plants were recovered from 4021 3x × 2x crosses. One triploid was relatively fertile in 3x × 4x and 3x × 6x crosses, which is most likely attributable to 2n gamete production in the triploid. The lack of fertility of triploids, which do not produce 2n gametes, in crosses with diploids and tetraploids suggests that the production of gametes with numerically balanced (n = 12 or 24) chromosome numbers is extremely low. In addition, the inability to recover progeny from 3x × 2x crosses also suggests that aneuploid gametophytes and/or zygotes, including trisomics, are inviable in blueberry. Pollen stainability was also highly reduced in triploids. Frequency distributions of anaphase I pole chromosomal constitutions of three triploids were significantly different from one another. Two of the three distributions were shifted toward the basic chromosome number of 12, with one triploid having 25% poles with 12 chromosomes. However, the sterility of 3x × 2x and 2x × 3x crosses indicates that lagging chromosomes during meiotic anaphases are probably not excluded from gametes, resulting in unbalanced gametes in blueberry. Triploids can be used as a bridge to facilitate gene transfer from the diploid and tetraploid levels to the hexaploid level in blueberry.

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