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 Transcriptome Analysis of Young Ovaries Reveals Candidate Genes Involved in Gamete Formation in Lantana camara

Plants ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 263 ◽  
Author(s):  
Ze Peng ◽  
Krishna Bhattarai ◽  
Saroj Parajuli ◽  
Zhe Cao ◽  
Zhanao Deng
Keyword(s):  
Candidate Genes ◽  
De Novo ◽  
Transcriptome Assembly ◽  
Gene Families ◽  
Unreduced Gametes ◽  
Lantana Camara ◽  
Unreduced Gamete ◽  
Genomic Resources ◽  
Gamete Formation ◽  
Gamete Production

Lantana (Lantana camara L., Verbenaceae) is an important ornamental crop, yet can be a highly invasive species. The formation of unreduced female gametes (UFGs) is a major factor contributing to its invasiveness and has severely hindered the development of sterile cultivars. To enrich the genomic resources and gain insight into the genetic mechanisms of UFG formation in lantana, we investigated the transcriptomes of young ovaries of two lantana genotypes, GDGHOP-36 (GGO), producing 100% UFGs, and a cultivar Landmark White Lantana (LWL), not producing UFGs. The de novo transcriptome assembly resulted in a total of 90,641 unique transcript sequences with an N50 of 1692 bp, among which, 29,383 sequences contained full-length coding sequences (CDS). There were 214 transcripts associated with the biological processes of gamete production and 10 gene families orthologous to genes known to control unreduced gamete production in Arabidopsis. We identified 925 transcription factor (TF)-encoding sequences, 91 nucleotide-binding site (NBS)-containing genes, and gene families related to drought/salt tolerance and allelopathy. These genomic resources and candidate genes involved in gamete formation will be valuable for developing new tools to control the invasiveness in L. camara, protect native lantana species, and understand the formation of unreduced gametes in plants.

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.

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 A Review of Unreduced Gametes and Neopolyploids in Alfalfa: How to Fill the Gap between Well-Established Meiotic Mutants and Next-Generation Genomic Resources

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 999
Author(s):  
Fabio Palumbo ◽  
Elisa Pasquali ◽  
Emidio Albertini ◽  
Gianni Barcaccia
Keyword(s):  
Reverse Genetics ◽  
Gene Diversity ◽  
Unreduced Gametes ◽  
Unreduced Gamete ◽  
Next Generation ◽  
Gene Characterization ◽  
Meiotic Mutants ◽  
Genomic Resources ◽  
Gamete Formation ◽  
2N Gamete

The gene flow mediated by unreduced gametes between diploid and tetraploid plants of the Medicago sativa–coerulea–falcata complex is pivotal for alfalfa breeding. Sexually tetraploidized hybrids could represent the best way to exploit progressive heterosis simultaneously derived from gene diversity, heterozygosity, and polyploidy. Moreover, unreduced gametes combined with parthenogenesis (i.e., apomixis) would enable the cloning of plants through seeds, providing a unique opportunity for the selection of superior genotypes with permanently fixed heterosis. This reproductive strategy has never been detected in the genus Medicago, but features of apomixis, such as restitutional apomeiosis and haploid parthenogenesis, have been reported. By means of an original case study, we demonstrated that sexually tetraploidized plants maintain apomeiosis, but this trait is developmentally independent from parthenogenesis. Alfalfa meiotic mutants producing unreduced egg cells revealed a null or very low capacity for parthenogenesis. The overall achievements reached so far are reviewed and discussed along with the efforts and strategies made for exploiting reproductive mutants that express apomictic elements in alfalfa breeding programs. Although several studies have investigated the cytological mechanisms responsible for 2n gamete formation and the inheritance of this trait, only a very small number of molecular markers and candidate genes putatively linked to unreduced gamete formation have been identified. Furthermore, this scenario has remained almost unchanged over the last two decades. Here, we propose a reverse genetics approach, by exploiting the genomic and transcriptomic resources available in alfalfa. Through a comparison with 9 proteins belonging to Arabidopsis thaliana known for their involvement in 2n gamete production, we identified 47 orthologous genes and evaluated their expression in several tissues, paving the way for novel candidate gene characterization studies. An overall view on strategies suitable to fill the gap between well-established meiotic mutants and next-generation genomic resources is presented and discussed.

scholarly journals Genome-wide study on the polysomic genetic factors conferring plasticity of flower sexuality in hexaploid persimmon

DNA Research ◽  
2020 ◽  
Vol 27 (3) ◽  
Author(s):  
Kanae Masuda ◽  
Eiji Yamamoto ◽  
Kenta Shirasawa ◽  
Noriyuki Onoue ◽  
Atsushi Kono ◽  
...  
Keyword(s):  
Genetic Factors ◽  
Diospyros Kaki ◽  
Dependent Manner ◽  
Male And Female ◽  
Association Analyses ◽  
Genome Wide ◽  
Allele Dosage ◽  
Partial Inactivation ◽  
In Cis ◽  
Segregating Population

Abstract Sexuality is one of the fundamental mechanisms that work towards maintaining genetic diversity within a species. In diploid persimmons (Diospyros spp.), separated sexuality, the presence of separate male and female individuals (dioecy), is controlled by the Y chromosome-encoded small-RNA gene, OGI. On the other hand, sexuality in hexaploid Oriental persimmon (Diospyros kaki) is more plastic, with OGI-bearing genetically male individuals, able to produce both male and female flowers (monoecy). This is thought to be linked to the partial inactivation of OGI by a retrotransposon insertion, resulting in DNA methylation of the OGI promoter region. To identify the genetic factors regulating branch sexual conversion, genome-wide correlation/association analyses were conducted using ddRAD-Seq data from an F1 segregating population, and using both quantitative and diploidized genotypes, respectively. We found that allelic ratio at the Y-chromosomal region, including OGI, was correlated with male conversion based on quantitative genotypes, suggesting that OGI can be activated in cis in a dosage-dependent manner. Genome-wide association analysis based on diploidized genotypes, normalized for the effect of OGI allele dosage, detected three fundamental loci associated with male conversion. These loci underlie candidate genes, which could potentially act epigenetically for the activation of OGI expression.

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 Quantitative Genotyping for the Astringency Locus in Hexaploid Persimmon Cultivars using Quantitative Real-time PCR

2010 ◽  
Vol 135 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Takashi Akagi ◽  
Yumi Takeda ◽  
Keizo Yonemori ◽  
Ayako Ikegami ◽  
Atsushi Kono ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Real Time ◽  
Real Time Pcr ◽  
Diospyros Kaki ◽  
Quantitative Real Time Pcr ◽  
Reference Sites ◽  
Chain Reaction ◽  
Marker Allele ◽  
Allele Dosage ◽  
Polymerase Chain

Persimmon (Diospyros kaki Thunb.) is generally hexaploid, and a single AST locus controls the pollination-constant non-astringency trait on each of six corresponding chromosomes. The pollination-constant non-astringent (PCNA) genotype is nulliplex and requires homozygous recessive alleles (ast) at the AST locus. There are several non-PCNA cultivars/selections that could be cross parents; however, the probability of yielding nulliplex offspring depends on the number of recessive alleles (ast). In genotyping for the AST locus in hexaploid persimmon, in contrast to the situation in diploid plants, we need to detect the AST/ast allele dosage; this cannot be detected by common codominant markers. In this study, we detected the allele dosage of Mast, which is a marker allele strongly linked to the ast allele among cultivars, by quantitative real-time polymerase chain reaction (qPCR) using three reference sites, actin (DkAct), anthocyanin reductase (DkANR), and L5R, whose sequences are conserved in the genome of persimmon cultivars. Based on the allele dosage of the Mast, AST/ast genotypes were estimated for 63 non-astringent cultivars/selections, of which only five cultivars/selections were estimated to be simplex or duplex. The quantitative genotyping method using qPCR may be generally effective for polyploid plants.

Intergenomic recombination in F1 lily hybrids (Lilium) and its significance for genetic variation in the BC1 progenies as revealed by GISH and FISH

Genome ◽  
2005 ◽  
Vol 48 (5) ◽  
pp. 884-894 ◽  
Author(s):  
R Barba-Gonzalez ◽  
M S Ramanna ◽  
R G.F Visser ◽  
J M Van Tuyl
Keyword(s):  
In Situ Hybridization ◽  
Phenotypic Expression ◽  
2N Gametes ◽  
Backcross Progeny ◽  
Unreduced Gametes ◽  
Normal Chromosome ◽  
Recombinant Chromosome ◽  
Intergenomic Recombination ◽  
A Genome

Intergenomic recombination was assessed in a BC1 population of Oriental (O) × Asiatic (A) lilies (Lilium) backcrossed to Asiatic parents. This population consisted of 38 plants generated from the 2n gametes from 2 genotypes (951502-1 and 952400-1) of the diploid F1, Oriental × Asiatic lilies (2n = 2x = 24) as parents. In the majority of BC1 plants, there was evidence that first division restitution, with and without crossovers, resulted in functional gametes. However, there were 5 BC1 plants in which 2n gametes originated from indeterminate meiotic restitution (IMR). Based on the number of recombinant chromosomes for a particular homoeologous pair, 3 types of plants were identified: (i) those with both the reciprocal product of a crossover (O/A, A/O, where O represents the centromere of the O genome and A the recombinant segment of Asiatic chromosome, and vice versa); (ii) those with 1 normal chromosome of the O genome and a recombinant chromosome (O, A/O); and (iii) those with 1 normal chromosome of the A genome and a recombinant chromosome (A, O/A). An important feature of A × OA backcross progeny is the occurrence of substitutions for the segment distal in the crossover wherever the recombinant chromosome O/A was present. In the case of IMR, the substitution occurred for both proximal and distal recombinant segments. The significance of these substitutions is that they offer the potential for the phenotypic expression of recessive genes in polyploids (i.e., nulliplex genotype).Key words: genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), unreduced gametes, allopolyploid.

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