scholarly journals Inbreeding Depression in Genotypically Matched Diploid and Tetraploid Maize

2020 ◽  
Vol 11 ◽  
Author(s):  
Hong Yao ◽  
Sanvesh Srivastava ◽  
Nathan Swyers ◽  
Fangpu Han ◽  
Rebecca W. Doerge ◽  
...  
Keyword(s):  
Inbreeding Depression ◽  
Molecular Basis ◽  
Opposite Effect ◽  
Inbred Lines ◽  
Field Conditions ◽  
F1 Hybrids ◽  
Multiple Generations ◽  
Self Pollination ◽  
Deleterious Alleles ◽  
Seven Generations

The genetic and molecular basis of heterosis has long been studied but without a consensus about mechanism. The opposite effect, inbreeding depression, results from repeated self-pollination and leads to a reduction in vigor. A popular explanation for this reaction is the homozygosis of recessive, slightly deleterious alleles upon inbreeding. However, extensive studies in alfalfa indicated that inbreeding between diploids and autotetraploids was similar despite the fact that homozygosis of alleles would be dramatically different. The availability of tetraploid lines of maize generated directly from various inbred lines provided the opportunity to examine this issue in detail in perfectly matched diploid and tetraploid hybrids and their parallel inbreeding regimes. Identical hybrids at the diploid and tetraploid levels were inbred in triplicate for seven generations. At the conclusion of this regime, F1 hybrids and selected representative generations (S1, S3, S5, S7) were characterized phenotypically in randomized blocks during the same field conditions. Quantitative measures of the multiple generations of inbreeding provided little evidence for a distinction in the decline of vigor between the diploids and the tetraploids. The results suggest that the homozygosis of completely recessive, slightly deleterious alleles is an inadequate hypothesis to explain inbreeding depression in general.

scholarly journals Effect of Meiotic Polyploidisation on Selected Morphological and Anatomical Traits in Interspecific Hybrids of Brassica oleracea × B. napus

Agronomy ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 26
Author(s):  
Agnieszka Marasek-Ciolakowska ◽  
Piotr Kamiński ◽  
Małgorzata Podwyszyńska ◽  
Urszula Kowalska ◽  
Michał Starzycki ◽  
...  
Keyword(s):  
Interspecific Hybrids ◽  
Pollen Viability ◽  
Inbred Lines ◽  
F1 Hybrids ◽  
Interspecific Hybridisation ◽  
Self Pollination ◽  
F2 Hybrids ◽  
F2 Generation ◽  
Head Cabbage ◽  
F1 Generation

In Brassica, interspecific hybridisation plays an important role in the formation of allopolyploid cultivars. In this study, the ploidy of F1 and F2 generations resulting from interspecific hybridisation between B. oleracea inbred lines of head cabbage (B. oleracea L. var. capitata) (2n = 18) and kale (B. oleracea L. var. acephala) (2n = 18) with inbred lines of rapeseed (B. napus L.) (2n = 38) was examined by flow cytometry analysis and chromosome observation. Furthermore, the effect of meiotic polyploidisation on selected phenotypic and anatomical traits was assessed. The F1 hybrids of head cabbage × rapeseed (S3) and kale × rapeseed crosses (S20) were allotriploids with 2n = 28 chromosomes, and nuclear DNA amounts of 1.97 (S3) and 1.99 pg (S20). These values were intermediate between B. oleracea and B. napus. In interspecific hybrids of the F2 generation, which were derived after self-pollination of F1 hybrids (FS3, FS20) or by open crosses between F1 generation hybrids (FC320, FC230), the chromosome numbers were similar 2n = 56 or 2n = 55, whereas the genome sizes varied between 3.81 (FS20) and 3.95 pg 2C (FC230). Allohexaploid F2 hybrids had many superior agronomic traits compared to parental B. napus and B. oleracea lines and triploid F1 hybrids. In the generative stage, they were characterised by larger flowers and flower elements, such as anthers and lateral nectaries. F2 hybrids were male and female fertile. The pollen viability of F2 hybrids was comparable to parental genotypes and varied from 75.38% (FS3) to 88.24% (FC320), whereas in triploids of F1 hybrids only 6.76% (S3) and 13.46% (S20) of pollen grains were fertile. Interspecific hybrids of the F2 generation derived by open crosses between plants of the F1 generation (FC320, FC230) had a better ability to set seed than F2 hybrids generated from the self-pollination of F1 hybrids. In the vegetative stage, F2 plants had bigger and thicker leaves, larger stomata, and significantly thicker layers of palisade and spongy mesophyll than triploids of the F1 generation and parental lines of B. oleracea and B. napus. The allohexaploid F2 hybrids analysed in this study can be used as innovative germplasm resources for further breeding new vegetable Brassica crops at the hexaploid level.

scholarly journals Recent approaches into the genetic basis of inbreeding depression in plants

2003 ◽  
Vol 358 (1434) ◽  
pp. 1071-1084 ◽  
Author(s):  
David E. Carr ◽  
Michele R. Dudash
Keyword(s):  
Inbreeding Depression ◽  
Genetic Basis ◽  
Genetic Load ◽  
Strong Support ◽  
Major Effect ◽  
Inbred Lines ◽  
Recessive Mutations ◽  
Deleterious Alleles ◽  
Experimental Approaches ◽  
Marker Segregation Distortion

Predictions for the evolution of mating systems and genetic load vary, depending on the genetic basis of inbreeding depression (dominance versus overdominance, epistasis and the relative frequencies of genes of large and small effect). A distinction between the dominance and overdominance hypotheses is that deleterious recessive mutations should be purged in inbreeding populations. Comparative studies of populations differing in their level of inbreeding and experimental approaches that allow selection among inbred lines support this prediction. More direct biometric approaches provide strong support for the importance of partly recessive deleterious alleles. Investigators using molecular markers to study quantitative trait loci (QTL) often find support for overdominance, though pseudo–overdominance (deleterious alleles linked in repulsion) may bias this perception. QTL and biometric studies of inbred lines often find evidence for epistasis, which may also contribute to the perception of overdominance, though this may be because of the divergent lines initially crossed in QTL studies. Studies of marker segregation distortion commonly uncover genes of major effect on viability, but these have only minor contributions to inbreeding depression. Although considerable progress has been made in understanding the genetic basis of inbreeding depression, we feel that all three aspects merit more study in natural plant populations.

scholarly journals Self Incompatibility, Inbreeding Depression, and Potential to Develop Inbred Lines in Alfalfa: A Review

2020 ◽  
Author(s):  
Atit Parajuli ◽  
Longxi Yu ◽  
Michael Peel ◽  
Deven See ◽  
Steven Wagner ◽  
...  
Keyword(s):  
Inbreeding Depression ◽  
Bulked Segregant Analysis ◽  
Inbred Lines ◽  
Dramatic Improvement ◽  
Dominant Model ◽  
Self Incompatibility ◽  
Dominance Model ◽  
Legume Crop ◽  
Dominant Phenotype ◽  
Deleterious Alleles

Alfalfa (Medicago sativa L.) is a perennial, outcrossing legume crop predominantly grown for hay, silage, or pasture. Intensive selection has resulted in dramatic improvement in fitness traits, including winter survival and disease resistance. However, there has been minimal improvement in other economically important traits, such as hay yield, which is still comparable to 30 years ago. Intensive phenotyping costs on this type of trait hinder high selection pressure to identify superior outcross individuals. Severe inbreeding depression inhibits the development of inbred lines with accumulated favorable alleles that exhibit heterosis. This review highlights the outcomes of inbreeding depression as well as the causes, including unmasking deleterious alleles and triggering self-incompatibility. We tracked the research efforts that unveil the genetic bases underlying deleterious alleles and self-incompatibility. The magnitudes of inbreeding depression were compared with the rate of heterozygous halved time in diploid and tetraploid organisms. To fill in the gaps between the controversy and existing hypotheses, we theorized a dosage dominant model of inheritance. The dosage dominant model is similar to the Mendelian dominance model, in which a genotype exhibits a dominant phenotype if there is a dominant allele (alphabet dominant). The difference is that in the dosage dominant model, a genotype will result in a dominant phenotype if the number of dominant alleles is equal to or greater than the number of recessive alleles. This review also includes a discussion on the development of pseudo inbreds and a hypothesis to identify deleterious alleles using bulked segregant analysis and consequently to purge deleterious alleles using marker-assisted selection, to progress toward the successful development of pure inbred lines in alfalfa.

scholarly journals Selection, Load and Inbreeding Depression in a Large Metapopulation

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 1191-1202 ◽  
Author(s):  
Michael C Whitlock
Keyword(s):  
Population Structure ◽  
Inbreeding Depression ◽  
Population Subdivision ◽  
Response To Selection ◽  
Mutation Load ◽  
Deleterious Alleles ◽  
Subdivided Population ◽  
Soft Selection ◽  
Mean Fitness ◽  
The Mean

Abstract The subdivision of a species into local populations causes its response to selection to change, even if selection is uniform across space. Population structure increases the frequency of homozygotes and therefore makes selection on homozygous effects more effective. However, population subdivision can increase the probability of competition among relatives, which may reduce the efficacy of selection. As a result, the response to selection can be either increased or decreased in a subdivided population relative to an undivided one, depending on the dominance coefficient FST and whether selection is hard or soft. Realistic levels of population structure tend to reduce the mean frequency of deleterious alleles. The mutation load tends to be decreased in a subdivided population for recessive alleles, as does the expected inbreeding depression. The magnitude of the effects of population subdivision tends to be greatest in species with hard selection rather than soft selection. Population structure can play an important role in determining the mean fitness of populations at equilibrium between mutation and selection.

scholarly journals Proteomic data from leaves of twenty-four sunflower genotypes underwater deficit

2020 ◽  
Author(s):  
Thierry Balliau ◽  
Harold Duruflé ◽  
Nicolas Blanchet ◽  
Mélisande Blein-Nicolas ◽  
Nicolas B. Langlade ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Water Deficit ◽  
High Throughput ◽  
Molecular Basis ◽  
Inbred Lines ◽  
Vegetative Stage ◽  
Valuable Resource ◽  
Proteomic Data ◽  
High Throughput Phenotyping

AbstractThis article describes how the proteomic data were produced on sunflower plants subjected to water deficit. Twenty-four sunflower genotypes were selected to represent genetic diversity within cultivated sunflower. They included both inbred lines and their hybridsWater deficit was applied to plants in pots at the vegetative stage using the high-throughput phenotyping platform Heliaphen. Here, we provide proteomic data from sunflower leaves corresponding to the identification of 3062 proteins and the quantification of 1211 of them in these 24 genotypes grown in two watering conditions. These data differentiate both treatment and the different genotypes and constitute a valuable resource to the community to study adaptation of crops to drought and the molecular basis of heterosis.

scholarly journals Селекция лука репчатого с устойчивостью к пероноспорозу

2019 ◽  
Author(s):  
G.F. Monakhos ◽  
S.G. Monakhos ◽  
R.R. Alizhanova
Keyword(s):  
Disease Resistance ◽  
Downy Mildew ◽  
Resistance Gene ◽  
Inbred Lines ◽  
F1 Hybrids ◽  
Downy Mildew Resistance ◽  
European Origin ◽  
Molecular Genotyping ◽  
Breeding Station ◽  
Selection Of

На Селекционной станции имени Н.Н. Тимофеева гибридизацией с донором устойчивости к пероноспорозу F1 Santero, беккроссом, инбридингом и отбором на инфекционном фоне с помощью молекулярного маркера DMR1 создано 15 линий лука репчатого гомозиготного по гену устойчивости Pd1. Оценка в однолетней культуре позволила выделить линии с массой луковиц 100120 г с высокой сохранностью, которые могут быть использованы в селекции F1 гибридов в качестве отцовских компонентов.Fifteen homozygous for Pd1 downy mildew resistance gene onion lines were developed by hybridization followed backcrossing F1 Santero of downy mildew resistant onion accession of European origin and a collection of onion inbred lines from LC Breeding station after N.N. Timofeev. The resistant to downy mildew, caused by Peronospora destructor (Berk.), plants were selected in segregated populations based on disease resistance test and molecular genotyping using DMR1marker. The lines with a mass of bulbs 100 120 g with high preservation, which can be used in the selection of F1 hybrids as paternal components.

RESISTANCE OF INBRED LINES AND HYBRIDS OF SUNFLOWERS (HELIANTHUS ANNUUS L.) IN A NATURAL EPIDEMIC OF ASTER YELLOWS

1960 ◽  
Vol 40 (2) ◽  
pp. 375-382 ◽  
Author(s):  
Eric D. Putt ◽  
W. E. Sackston
Keyword(s):  
Helianthus Annuus ◽  
Inbred Lines ◽  
Field Conditions ◽  
Single Plant ◽  
Aster Yellows ◽  
Helianthus Annuus L ◽  
Single Cross ◽  
Single Cross Hybrids

Resistance to aster yellows has been identified in sunflowers. In 560 inbred lines and single plant progenies, 356 showed no symptoms of the disease under field conditions. The others showed infections ranging up to 100 per cent. Six entries, observed at three points, showed a range of infection from 0 to 86 per cent and eighteen others, at two points, a range from 0 to 73 per cent. The behaviour was consistent at the different locations.The resistance to aster yellows appeared to be qualitatively inherited. Single cross hybrids between resistant and, susceptible lines showed the resistance to be dominant. It occurred in association both with susceptibility and with resistance to rust. Of 15 lines with evidence of resistance to leaf mottle disease, 13 lines also had resistance to aster yellows.

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