GENETIC RELATIONSHIPS BETWEEN DIPLOIDS AND TETRAPLOIDS IN SERIES EUBARBATAE OF AVENA

1968 ◽  
Vol 10 (1) ◽  
pp. 68-81 ◽  
Author(s):  
Gideon Ladizinsky ◽  
Daniel Zohary
Keyword(s):  
Gene Flow ◽  
Genetic Relationships ◽  
Extreme Case ◽  
Meiotic Behavior ◽  
Ploidy Levels ◽  
Single Genome ◽  
In Series ◽  
Full Shift ◽  
Tetraploid Level ◽  
Diploid Level

Diploid (2n = 14) and tetraploid (2n = 28) entities in series Eubarbatae of the genus Avena have been found to be genetically closely linked and are regarded as a single polyploid complex. At both ploidy levels the various morphological types are interfertile. Diploids and tetraploids are largely sympatric in their distribution and converge considerably in their ranges of morphological variation. Contacts between diploids and tetraploids are common and blurred morphological boundaries characterize mixed populations.The possibility of gene flow between diploids and tetraploids has been indicated by the behavior of triploid F1 hybrids. Such hybrids have been found to be partially fertile. In their progeny a conspicuous restoration of fertility is apparent: numerous plants of the F2 generation have been stabilized around the tetraploid level, few around the diploid level. In contact areas, triploids can be regarded as efficient bridges of gene flow between the two ploidy levels.The range of variation found at the tetraploid level is fully explicable by the variation present in the diploid races. Tetraploids are therefore regarded to have had an inter-varietal origin, i.e. have evolved from a single genome. They apparently represent an extreme case of bivalentization, where a full shift from an autotetraploid to an allotetraploid meiotic behavior had occurred. Meiotic behavior of the F2 plants also indicate such origin.

Chromosome pairing and chiasma formation in autopolyploids of different Lathyrus species

Genome ◽  
1997 ◽  
Vol 40 (6) ◽  
pp. 937-944 ◽  
Author(s):  
H. I. T. Khawaja ◽  
J. Sybenga ◽  
J. R. Ellis
Keyword(s):  
Gene Flow ◽  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Chiasma Formation ◽  
Meiotic Metaphase ◽  
Lathyrus Sativus ◽  
Ploidy Levels ◽  
Lathyrus Odoratus ◽  
Mixed Populations ◽  
Tetraploid Level

Chromosome pairing and chiasma formation were studied in natural and induced tetraploids (2n = 28) of Lathyrus odoratus (induced), Lathyrus pratensis (natural and induced), Lathyrus sativus (induced), and Lathyrus venosus (natural), as well as in triploids of L. pratensis and diploids of L. odoratus, L. pratensis, and L. sativus. All natural tetraploids appeared to be autotetraploids and their meiotic metaphase I behaviour was very similar to that of the induced autotetraploids, with average numbers of pairing partner switches exceeding 4 or even 5. Multivalent frequencies were high, but the numbers of chiasmata were not much higher than necessary to maintain the configurations. Interstitial chiasmata were common, but not predominant. Fertility was reduced, but sufficient for predominantly vegetatively reproducing species. The triploids of L. pratensis had an even higher multivalent frequency than the tetraploids, but still produced some viable progeny at or close to the tetraploid level, suggesting that in mixed populations of diploids and tetraploids, triploids can contribute to gene flow between the ploidy levels. There was no significant correlation between chiasma frequency and ring bivalent frequency in the diploids and multivalent frequency in the corresponding tetraploids. In the tetraploids, chiasma frequency and multivalent frequency were negatively correlated.Key words: Lathyrus, natural, induced, autotetraploid, triploid, meiosis.

scholarly journals Production of hybrid potatoes: Are heterozygosity and ploidy levels important?

2019 ◽  
pp. 687-694
Author(s):  
Jane Muthoni ◽  
Hussein Shimelis ◽  
Rob Melis
Keyword(s):  
Genetic Basis ◽  
Potato Breeding ◽  
Allelic Diversity ◽  
Solanum Species ◽  
Ploidy Levels ◽  
Cultivated Potato ◽  
Tetraploid Level ◽  
Diploid Level ◽  
Do So

It has been proposed that maximizing heterosis for yield in potato may be achieved by maximizing heterozygosity and associated intra and interlocus interactions. Tetraploids offer more opportunities to create such interactions than diploids hence the general observations that tetraploids are higher yielding than diploids. Consequently, efforts have been made to increase heterozygosity in tetraploids by introgressing allelic diversity from other Solanum species into cultivated potato. However, conventional potato breeding is difficult because the cultivated potato is an autotetraploid with tetrasomic inheritance and it comprises highly heterozygous individuals which suffer inbreeding depression upon selfing; breeding at the tetraploid level is slow and less efficient than at diploid level. At the diploid level, it is possible to breed for and fix traits under recessive genetic control; it is nearly impossible to do so at the tetraploid level. There is also rapid response to selection due to greater variation in diploids than tetraploids. Consequently, there have been efforts to convert potato from an asexually propagated tetraploid crop into an inbred seed-propagated diploid; this is by production of inbred lines through selfing of the tetraploids to assemble desirable combinations of genes in the inbreds. These efforts are at the experimental stages and a lot of research needs to be done before they are confirmed. Because currently there is little experimental evidence to support superiority of the inbred seed-propagated diploid strategy, it appears the theory that heterosis for yield in potato may be achieved by maximizing heterozygosity and associated intra and interlocus interactions remain unchallenged; these interactions are more in tetraplods than in diploids. This paper therefore looks at genetic basis of yield heterosis in cultivated potato and the role of heterozygosity and ploidy level in production of hybrid potatoes.

Habitat differentiation between estuarine and inland Hibiscus tiliaceus L. (Malvaceae) as revealed by retrotransposon-based SSAP marker

2011 ◽  
Vol 59 (6) ◽  
pp. 515 ◽  
Author(s):  
Tian Tang ◽  
Lian He ◽  
Feng Peng ◽  
Suhua Shi
Keyword(s):  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Distance ◽  
Genetic Variance ◽  
Genetic Relationships ◽  
Principal Coordinate Analysis ◽  
Geographical Isolation ◽  
Tidal Zone ◽  
Ecological Scale ◽  
Habitat Differentiation

Hibiscus tiliaceus L. (Malvaceae) is a pantropical coastal tree that extends to the tidal zone. In this study, the retrotransposon sequence-specific amplified polymorphism (SSAP) technique was used in order to understand the genetic variation between four population pairs of H. tiliaceus from repeated estuarine and inland habitat contrasts in China. The estuarine populations were consistently more genetic variable compared with the inland ones, which may be attributed to extensive gene flow via water-drifted seeds and/or retrotransposon activation in stressful estuarine environments. An AMOVA revealed that 8.9% of the genetic variance could be explained by the habitat divergence within site, as compared with only 4.9% to geographical isolation between sites, which indicates significant habitat differentiation between the estuarine and inland populations. The estuarine populations were less differentiated (ΦST = 0.115) than the inland (ΦST = 0.152) implying frequent gene interchange in the former. Accordingly, the principal coordinate analysis of genetic distance between individuals revealed that genetic relationships are not fully consistent with the geographic association. These results suggest that despite substantial gene flow via sea-drifted seeds, habitat-related divergent selection could be one of the primary mechanisms that drive habitat differentiation in H. tiliaceus at a local ecological scale.

scholarly journals Genetic Diversity and Population Structure of Bermudagrass [Cynodon dactylon (L.) Pers.] along Latitudinal Gradients and the Relationship with Polyploidy Level

Diversity ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 135 ◽  
Author(s):  
Jingxue Zhang ◽  
Miaoli Wang ◽  
Zhipeng Guo ◽  
Yongzhuo Guan ◽  
Jianyu Liu ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Population Genetic ◽  
Cynodon Dactylon ◽  
Latitudinal Gradients ◽  
Wind Pollination ◽  
Ploidy Levels ◽  
Sexual And Asexual Reproduction ◽  
Genetic Pattern

Understanding the population genetic pattern and process of gene flow requires a detailed knowledge of how landscape characteristics structure populations. Although Cynodon dactylon (L.) Pers. (common bermudagrass) is widely distributed in the world, information on its genetic pattern and population structure along latitudinal gradients is limited. We tried to estimate the genetic diversity and genetic structure of C. dactylon along a latitudinal gradient across China. Genetic diversity among different ploidy levels was also compared in the study. The material used consisted of 296 C. dactylon individuals sampled from 16 geographic sites from 22°35′ N to 36°18′ N. Genetic diversity was estimated using 153 expressed sequence tag-derived simple sequence repeat (EST-SSR) loci. Higher within-population genetic diversity appeared at low-latitude, as well as having positive correlation with temperature and precipitation. The genetic diversity increased with the ploidy level of C. dactylon, suggesting polyploidy creates higher genetic diversity. No isolation by distance and notable admixture structure existed among populations along latitudes. Both seed dispersal (or vegetative organs) and extrinsic pollen played important roles for gene flow in shaping the spatial admixture population structure of C. dactylon along latitudes. In addition, populations were separated into three clusters according to ploidy levels. C. dactylon has many such biological characters of perennial growth, wind-pollination, polyploidy, low genetic differentiation among populations, sexual and asexual reproduction leading to higher genetic diversity, which gives it strong adaptability with its genetic patterns being very complex across all the sampled latitudes. The findings of this study are related to landscape population evolution, polyploidy speciation, preservation, and use of bermudagrass breeding.

Genetic variation of microsatellite and mitochondrial DNA markers in broad whitefish (Coregonus nasus) in the Colville and Sagavanirktok rivers in northern Alaska

1997 ◽  
Vol 54 (7) ◽  
pp. 1548-1556 ◽  
Author(s):  
J C Patton ◽  
B J Gallaway ◽  
R G Fechhelm ◽  
M A Cronin
Keyword(s):  
Mitochondrial Dna ◽  
Genetic Variation ◽  
Gene Flow ◽  
Microsatellite Loci ◽  
Genetic Relationships ◽  
Nuclear Genome ◽  
Pcr Amplification ◽  
Colville River ◽  
Limited Gene Flow ◽  
Northern Alaska

There has been concern that a causeway leading to oil production facilities in the Alaskan Beaufort Sea could affect the extent of emigration from, and immigration into, a population of broad whitefish (Coregonus nasus) in the Sagavanirktok River. To assess this, we analyzed the genetic relationships of the broad whitefish populations in the Sagavanirktok River, and the nearest adjacent population, in the Colville River. Three microsatellite loci from the nuclear genome, and the NADH-1 gene of mitochondrial DNA (mtDNA), were analyzed. Diploid genotypes were determined with PCR amplification of the microsatellite loci, and mtDNA genotypes were identified with PCR amplification followed by sequencing of 798 nucleotides. Several alleles were identified at each locus and both populations had high levels of genetic variation. There is significant differentiation of the Sagavanirktok River and Colville River broad whitefish stocks for the three microsatellite loci (FST = 0.031) but not mtDNA (FST < 0.001). Possible explanations for the lower level of differentiation of mtDNA than microsatellites include female-mediated gene flow between populations, skewed sex ratios, natural selection, or mutation. The results indicate that there is limited gene flow between the Colville and Sagavanirktok rivers, which represent semi-isolated spawning populations.

scholarly journals Molecular diversity and phylogeny of Triticum-Aegilops species possessing D genome revealed by SSR and ISSR markers

2015 ◽  
Vol 71 (1) ◽  
pp. 81-95 ◽  
Author(s):  
Hoda Moradkhani ◽  
Ali Ashraf Mehrabi ◽  
Alireza Etminan ◽  
Alireza Pour-Aboughadareh
Keyword(s):  
Genetic Diversity ◽  
Gene Diversity ◽  
Genetic Relationships ◽  
Issr Markers ◽  
Issr Marker ◽  
D Genome ◽  
Ploidy Levels ◽  
Marker Data ◽  
Geographical Regions ◽  
High Level

AbstractThe aim of this study is investigation the applicability of SSR and ISSR markers in evaluating the genetic relationships in twenty accessions ofAegilopsandTriticumspecies with D genome in different ploidy levels. Totally, 119 bands and 46 alleles were detected using ten primers for ISSR and SSR markers, respectively. Polymorphism Information Content values for all primers ranged from 0.345 to 0.375 with an average of 0.367 for SSR, and varied from 0.29 to 0.44 with the average 0.37 for ISSR marker. Analysis of molecular variance (AMOVA) revealed that 81% (ISSR) and 84% (SSR) of variability was partitioned among individuals within populations. Comparing the genetic diversity ofAegilopsandTriticumaccessions, based on genetic parameters, shows that genetic variation ofAe. crassaandAe. tauschiispecies are higher than other species, especially in terms of Nei’s gene diversity. Cluster analysis, based on both markers, separated total accessions in three groups. However, classification based on SSR marker data was not conformed to classification according to ISSR marker data. Principal co-ordinate analysis (PCoA) for SSR and ISSR data showed that, the first two components clarified 53.48% and 49.91% of the total variation, respectively. This analysis (PCoA), also, indicated consistent patterns of genetic relationships for ISSR data sets, however, the grouping of accessions was not completely accorded to their own geographical origins. Consequently, a high level of genetic diversity was revealed from the accessions sampled from different eco-geographical regions of Iran.

scholarly journals Non-linear genetic diversity and notable population differentiation caused by low gene flow of bermudagrass [Cynodon dactylon (L.) Pers.] along longitude gradients

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11953
Author(s):  
Jing-Xue Zhang ◽  
Miaoli Wang ◽  
Jibiao Fan ◽  
Zhi-Peng Guo ◽  
Yongzhuo Guan ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Genetic Distance ◽  
Ploidy Level ◽  
Population Genetic ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
Ploidy Levels ◽  
Population Genetic Diversity

Background Environmental variation related to ecological habitat is the main driver of plant adaptive divergence. Longitude plays an important role in the formation of plant population structure, indicating that environmental differentiation can significantly shape population structure. Methods Genetic diversity and population genetic structure were estimated using 105 expressed sequence tag-derived simple sequence repeat (EST-SSR) loci. A total of 249 C. dactylon (L.) Pers. (common bermudagrass) individuals were sampled from 13 geographic sites along the longitude (105°57′34″–119°27′06″E). Results There was no obvious linear trend of intra-population genetic diversity along longitude and the intra-population genetic diversity was not related to climate in this study. Low gene flow (Nm = 0.7701) meant a rich genetic differentiation among populations of C. dactylon along longitude gradients. Significantly positive Mantel correlation (r = 0.438, P = 0.001) was found between genetic distance and geographical interval while no significant partial Mantel correlation after controlling the effect of mean annual precipitation, which indicated geographic distance correlated with mean annual precipitation affect genetic distance. The genetic diversity of C. dactylon with higher ploidy level was higher than that with lower ploidy level and groups of individuals with higher ploidy level were separated further away by genetic distance from the lower ploidy levels. Understanding the different genetic bases of local adaptation comparatively between latitude and longitude is one of the core findings in the adaptive evolution of plants.

scholarly journals Contrasted histories of organelle and nuclear genomes underlying physiological diversification in a grass species

2020 ◽  
Vol 287 (1938) ◽  
pp. 20201960
Author(s):  
Matheus E. Bianconi ◽  
Luke T. Dunning ◽  
Emma V. Curran ◽  
Oriane Hidalgo ◽  
Robyn F. Powell ◽  
...  
Keyword(s):  
Gene Flow ◽  
Population Genomics ◽  
Nuclear Genome ◽  
Its Region ◽  
Grass Species ◽  
Region Of Origin ◽  
Ploidy Levels ◽  
Lower Elevation ◽  
Limited Dispersal ◽  
Genome Analyses

C 4 photosynthesis evolved multiple times independently in angiosperms, but most origins are relatively old so that the early events linked to photosynthetic diversification are blurred. The grass Alloteropsis semialata is an exception, as this species encompasses C 4 and non-C 4 populations. Using phylogenomics and population genomics, we infer the history of dispersal and secondary gene flow before, during and after photosynthetic divergence in A. semialata . We further analyse the genome composition of individuals with varied ploidy levels to establish the origins of polyploids in this species. Detailed organelle phylogenies indicate limited seed dispersal within the mountainous region of origin and the emergence of a C 4 lineage after dispersal to warmer areas of lower elevation. Nuclear genome analyses highlight repeated secondary gene flow. In particular, the nuclear genome associated with the C 4 phenotype was swept into a distantly related maternal lineage probably via unidirectional pollen flow. Multiple intraspecific allopolyploidy events mediated additional secondary genetic exchanges between photosynthetic types. Overall, our results show that limited dispersal and isolation allowed lineage divergence, with photosynthetic innovation happening after migration to new environments, and pollen-mediated gene flow led to the rapid spread of the derived C 4 physiology away from its region of origin.

scholarly journals Whole genome duplication potentiates inter-specific hybridisation and niche shifts in Australian burrowing frogs Neobatrachus

2019 ◽  
Author(s):  
Polina Yu. Novikova ◽  
Ian G. Brennan ◽  
William Booker ◽  
Michael Mahony ◽  
Paul Doughty ◽  
...  
Keyword(s):  
Gene Flow ◽  
Sequence Data ◽  
Diploid Species ◽  
Exome Capture ◽  
Polyploid Species ◽  
Ploidy Levels ◽  
Population Genomic ◽  
Niche Shifts ◽  
Inheritance Mode ◽  
The Impact

Polyploidy has played an important role in evolution across the tree of life but it is still unclear how polyploid lineages may persist after their initial formation. While both common and well-studied in plants, polyploidy is rare in animals and generally less well-understood. The Australian burrowing frog genus Neobatrachus is comprised of six diploid and three polyploid species and offers a powerful animal polyploid model system. We generated exome-capture sequence data from 87 individuals representing all nine species of Neobatrachus to investigate species-level relationships, the origin and inheritance mode of polyploid species, and the population genomic effects of polyploidy on genus-wide demography. We resolve the phylogenetic relationships among Neobatrachus species and provide further support that the three polyploid species have independent autotetraploid origins. We document higher genetic diversity in tetraploids, resulting from widespread gene flow specifically between the tetraploids, asymmetric inter-ploidy gene flow directed from sympatric diploids to tetraploids, and current isolation of diploid species from each other. We also constructed models of ecologically suitable areas for each species to investigate the impact of climate variation on frogs with differing ploidy levels. These models suggest substantial change in suitable areas compared to past climate, which in turn corresponds to population genomic estimates of demographic histories. We propose that Neobatrachus diploids may be suffering the early genomic impacts of climate-induced habitat loss, while tetraploids appear to be avoiding this fate, possibly due to widespread gene flow into tetraploid lineages specifically. Finally, we demonstrate that Neobatrachus is an attractive model to study the effects of ploidy on the evolution of adaptation in animals.

scholarly journals Gene flow among wild and cultivated common walnut (Juglans regia) trees in the Qinling Mountains revealed by microsatellite markers

2020 ◽  
Author(s):  
Huijuan Zhou ◽  
Peng Zhao ◽  
Keith Woeste ◽  
Shuoxin Zhang
Keyword(s):  
Gene Flow ◽  
Microsatellite Markers ◽  
Genetic Relationships ◽  
Juglans Regia ◽  
Pollen Flow ◽  
Qinling Mountains ◽  
Female Partners ◽  
Genetic Pollution ◽  
High Level ◽  
Common Walnut

AbstractPatterns of gene flow and gene introgression can be used to assess the risk of genetic pollution of wild forest trees from widespread cultivated trees. A comprehensive understanding of the genetic relationships and levels of gene flow among wild and cultivated common walnut (Juglans regia) has become an urgent issue. Using twelve microsatellite markers, we investigated the genetic diversity and gene flow between cultivated and wild trees of J. regia in the Qinling Mountains, China. A high level of genetic variation was detected in both cultivated and wild trees. The mean number of alleles per locus was 17.5. Observed heterozygosity (HO) and expected heterozygosity (HE) were 0.777 and 0.800, respectively. Pollination of mother trees was not by nearest neighbors, and a paternity of 60.7% of offspring evaluated could not be assigned to a local, sampled tree. Pollen flow from cultivated trees to wild trees was infrequent (5.4%), and selfing rates ranged from zero to 25.0%. Male parents were located from 0 to 1005 m from their female partners, with an average pollination distance of 285.1 m. These results are discussed in light of the cultivated species' diversity, outlining the frequent spontaneous genetic contributions from the wild to the cultivated compartment. In addition, the pollen flow parameters provide useful information about the dynamics of pollen movement within J. regia populations.

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