Opportunities from the use of protoplasts

1981 ◽  
Vol 292 (1062) ◽  
pp. 557-568 ◽  
Keyword(s):  
Genetic Variation ◽  
Plant Regeneration ◽  
Plant Breeding ◽  
Vector System ◽  
Plant Protoplasts ◽  
Wild Type ◽  
Additional Method ◽  
Crop Species ◽  
Direct Transformation ◽  
Fusion Of Protoplasts

Plant protoplasts of several horticultural and crop species can now be readily regenerated into plants. There are now available several opportunities for their use in the manipulation of genetic systems in plant breeding. Protoplast cloning has recently been shown to produce additional genetic variation in potatoes; the possibility is examined for protoplast cloning of seed producing crop species for new genetic variation. Fusion of protoplasts of different species is now providing an additional method of hybridization; sexually incompatible species can be hybridized and horticulturally useful hybrids are now being produced. Many possibilities exist for hybridization assessments, both nuclear and cytoplasmic, between various crop species; however, the extent to which these wider hybridizations will produce useful genetic variation is not yet clear, and in many instances plant regeneration from these cultured cell hybrids is not yet possible. Plant protoplasts are also providing an opportunity for the transfer of genes between different species. This may be by fusion with an irradiated protoplast system, or by direct transformation. Transfer of genes by using Agrobacterium plasmid as a vector system appears promising, and fusions with wild-type protoplasts will ensure the regeneration of non-tumorous plants.

scholarly journals UNEQUAL CROSSING OVER AT THE rRNA TANDON AS A SOURCE OF QUANTITATIVE GENETIC VARIATION IN DROSOPHILA

Genetics ◽  
1980 ◽  
Vol 95 (3) ◽  
pp. 727-742 ◽  
Author(s):  
R Frankham ◽  
D A Briscoe ◽  
R K Nurthen
Keyword(s):  
Genetic Variation ◽  
Selection Response ◽  
Crossing Over ◽  
Wild Type ◽  
X Chromosomes ◽  
Unequal Crossing Over ◽  
Quantitative Genetic ◽  
Y Chromosomes ◽  
Homozygous Line ◽  
Minimum Estimate

ABSTRACT Abdominal bristle selection lines (three high and three low) and controls were founded from a marked homozygous line to measure the contribution of sex-linked "mutations" to selection response. Two of the low lines exhibited a period of rapid response to selection in females, but not in males. There were corresponding changes in female variance, in heritabilities in females, in the sex ratio (a deficiency of females) and in fitness, as well as the appearance of a mutant phenotype in females of one line. All of these changes were due to bb alleles (partial deficiencies for the rRNA tandon) in the X chromosomes of these lines, while the Y chromosomes remained wild-type bb+. We argue that the bb alleles arose by unequal crossing over in the rRNA tandon.—A prediction of this hypothesis is that further changes can occur in the rRNA tandon as selection is continued. This has now been shown to occur.—Our minimum estimate of the rate of occurrence of changes at the rRNA tandon is 3 × 10-4. As this is substantially higher than conventional mutation rates, the questions of the mechanisms and rates of origin of new quantitative genetic variation require careful re-examination.

Epidemiologic Patterns of Wild-Type Hepatitis A Virus Determined by Genetic Variation

1991 ◽  
Vol 163 (2) ◽  
pp. 286-292 ◽  
Author(s):  
B. H. Robertson ◽  
B. Khanna ◽  
O. V. Nainan ◽  
H. S. Margolis
Keyword(s):  
Genetic Variation ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Wild Type

Abstract 1805: Chromosome 9p21.3 Genetic Variation is Associated with Angiographic CAD but not with CAD Disease Burden

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Chrissa P Mower ◽  
Jeffrey L Anderson ◽  
Benjamin D Horne ◽  
James J Park ◽  
Jesse L Coleman ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Disease Burden ◽  
Disease Onset ◽  
Cardiac Risk ◽  
Wild Type ◽  
Chi Square ◽  
High Risk Disease ◽  
Chi Square Test ◽  
Male Frequency ◽  
Cad Risk

Genetic variation at the 9p21.3 locus rs2383206 is associated with coronary heart disease (CHD) phenotypes. In a comparison of patients with and without angiographically confirmed CHD, the G allele of rs2383206 was present more frequently in diseased vs controls (normal angiograms). However, the pathophysiologic impact, whether it affects initiation, severity, or triggers an event, of the 9p21.3 locus remains unknown. We sought to determine whether 9p21.3 variation affects disease severity (promotion) by assessing its association with CAD burden. Methods: Genotyping for rs2383206 using 5′exonuclease chemistry (Taqman) was performed on 1759 subjects. Subjects were grouped as homozygous wild-type (low risk), heterozygous (intermediate risk) or homozygous risk-associated genotype (high risk). Disease burden was assessed by 1, 2, or 3 vessels; ≥70% stenosis and the validated Duke CAD Index (DCI). Comparison used a chi-square test (single vs multivessel disease) and analysis of variance (ANOVA) for the DCI comparison. Results: Average age 51.1± 7.4 years, 64.0% male. Frequency of the CAD risk allele did not differ among groups with 1, 2, or 3 vessel disease. There was no difference among groups with respect to the DCI. After adjustment for standard cardiac risk factors, the rs2383206 genotype was associated with CAD compared to controls (OR (CI)=1.73(1.26–1.85), p=0.001). Conclusion: The rs2383206 polymorphism was not associated with CAD disease burden. Findings suggest the rs2383206 polymorphism, although associated with disease onset is not likely involved in its progression. These findings will aid in refining the application of 9p21.3 for risk assessment and developing novel preventive and therapeutic strategies.

Plant Protoplasts and Genetic Variation

2018 ◽  
pp. 139-149
Author(s):  
Richard I. S. Brettell ◽  
Philip J. Larkin
Keyword(s):  
Genetic Variation ◽  
Plant Protoplasts

The genetic framework of plant breeding

1981 ◽  
Vol 292 (1062) ◽  
pp. 407-419 ◽  
Keyword(s):  
Plant Breeding ◽  
Recombinant Inbred ◽  
Recombinant Inbred Lines ◽  
Inbred Lines ◽  
Single Seed Descent ◽  
Crop Species ◽  
Biometrical Genetics ◽  
Mendelian Genetics ◽  
Linkage Disequilibria ◽  
Random Samples

The phenotypic variation that the breeder must manipulate to produce improved genotypes typically contains contributions from both heritable and non-heritable sources as well as from interactions between them. The totality of this variation can be understood only in terms of a methodology such as that of biometrical genetics - an extension of classical Mendelian genetics that retains all of its analytical, interpretative and predictive powers but only in respect of the net or summed effects of all contributing gene loci. In biometrical genetics the statistics that describe the phenotypic distributions are themselves completely described by heritable components based on the known types of gene action and interaction in combination with nonheritable components defined by the statistical properties of the experimental design. Biometrical genetics provides a framework for investigating the genetical basis and justification for current plant breeding strategies that are typified by the production of F 1 hybrids at one extreme and recombinant inbred lines at the other. From the early generations of a cross it can extract estimates of the heritable components of the phenotypic distributions that provide all the information required to interpret the cause of F 1 heterosis and predict the properties of any generation that can subsequently be derived from the cross. Applications to crosses in experimental and crop species show that true overdominance is not a cause of F 1 heterosis, although spurious overdominance arising from linkage disequilibria and non-allelic interactions can be. Predictions of the phenotypic distributions and ranges of recombinant inbred lines that should be extractable from these crosses are confirmed by observations made on random samples of inbred families produced from them by single seed descent. Within these samples, recombinant inbred lines superior to existing inbred lines and their F 1 hybrids are observed with the predicted frequencies.

Mutational analysis of centromere DNA from chromosome VI of Saccharomyces cerevisiae

1988 ◽  
Vol 8 (6) ◽  
pp. 2523-2535
Author(s):  
J H Hegemann ◽  
J H Shero ◽  
G Cottarel ◽  
P Philippsen ◽  
P Hieter
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitotic Chromosome ◽  
Mutational Analysis ◽  
Point Mutations ◽  
Vector System ◽  
Chromosome Loss ◽  
Wild Type ◽  
Sequence Elements ◽  
Chromosome Fragments

Saccharomyces cerevisiae centromeres have a characteristic 120-base-pair region consisting of three distinct centromere DNA sequence elements (CDEI, CDEII, and CDEIII). We have generated a series of 26 CEN mutations in vitro (including 22 point mutations, 3 insertions, and 1 deletion) and tested their effects on mitotic chromosome segregation by using a new vector system. The yeast transformation vector pYCF5 was constructed to introduce wild-type and mutant CEN DNAs onto large, linear chromosome fragments which are mitotically stable and nonessential. Six point mutations in CDEI show increased rates of chromosome loss events per cell division of 2- to 10-fold. Twenty mutations in CDEIII exhibit chromosome loss rates that vary from wild type (10(-4)) to nonfunctional (greater than 10(-1)). These results directly identify nucleotides within CDEI and CDEIII that are required for the specification of a functional centromere and show that the degree of conservation of an individual base does not necessarily reflect its importance in mitotic CEN function.

scholarly journals Comparison and Application of Non-Destructive NIR Evaluations of Seed Protein and Oil Content in Soybean Breeding

Agronomy ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 77 ◽  
Author(s):  
Guo-Liang Jiang
Keyword(s):  
Plant Breeding ◽  
Oil Content ◽  
Near Infrared ◽  
Regression Equations ◽  
Single Plant ◽  
Crop Species ◽  
Soybean Breeding ◽  
Plant Breeding Program ◽  
Significant Difference ◽  
Non Destructive

A plant breeding program needs to evaluate a large number of materials for different traits within a limited time. Near-infrared (NIR) spectroscopy has been used to quickly determine seed composition in various crop species. In this study, we compared whole-seed evaluations of protein and oil content by NIR methods in soybean [Glycine max (L.) Merr.], and then discussed the application to plant breeding. The differences among the entries tested were highly significant in both traits for each method used. No significant difference but high correlation and consistency existed between DA 7250 and wet-chemistry methods. Compared with DA 7250, ZX-50 exhibited, to some extent, differences or errors. The differences of ZX-50 methods were found to be correlated with seed sizes and could be corrected using regression equations formulated for bias calculation. After correction, the differences in the predictions between DA 7250 and ZX-50 methods were insignificant. Similar to DA 7250, ZX-50 methods exhibited a high repeatability (> 98%) of the predictions. By validation with 760 bulk samples of different seed types and 240 single-plant samples, it further demonstrated that as a non-destructive, fast and cost-efficient method, ZX-50 NIR analysis with an appropriate bias correction could be used in soybean breeding, specifically suitable for single plant selection based on whole seeds.

scholarly journals How a Genetically Stable Extremophile Evolves: Modes of Genome Diversification in the Archaeon Sulfolobus acidocaldarius

2017 ◽  
Vol 199 (17) ◽  
Author(s):  
Dominic Mao ◽  
Dennis W. Grogan
Keyword(s):  
Dna Repair ◽  
Genetic Variation ◽  
Tandem Repeats ◽  
Local Population ◽  
Genome Structure ◽  
Sulfolobus Acidocaldarius ◽  
Hyperthermophilic Archaea ◽  
Wild Type ◽  
Induced Mutations ◽  
Content Type

ABSTRACT In order to analyze in molecular terms how Sulfolobus genomes diverge, damage-induced mutations and natural polymorphisms (PMs) were identified in laboratory constructs and wild-type isolates, respectively, of Sulfolobus acidocaldarius. Among wild-type isolates drawn from one local population, pairwise nucleotide divergence averaged 4 × 10−6, which is about 0.15% of the corresponding divergence reported for Sulfolobus islandicus. The most variable features of wild-type S. acidocaldarius genomes were homopolymer (mononucleotide) tracts and longer tandem repeats, consistent with the spontaneous mutations that occur under laboratory conditions. Natural isolates, however, also revealed large insertions/deletions and inversions, which did not occur in any of the laboratory-manipulated strains. Several of the large insertions/deletions could be attributed to the integration or excision of mobile genetic elements (MGEs), and each MGE represented a distinct system of site-specific recombination. The mode of recombination associated with one MGE, a provirus related to Sulfolobus turreted icosahedral virus, was also seen in certain chromosomal inversions. Artificially induced mutations, non-MGE insertions/deletions, and small PMs exhibited different distributions over the genome, suggesting that large-scale patterning of Sulfolobus genomes begins early in the divergence process. Unlike induced mutations, natural base pair substitutions occurred in clusters, and one cluster exhibited properties expected of nonreciprocal recombination (gene conversion) between dispersed imperfect repeats. Taken together, the results identify simple replication errors, slipped-strand events promoted by tandem repeats, homologous recombination, and rearrangements promoted by MGEs as the primary sources of genetic variation for this extremely acidophilic archaeon in its geothermal environment. IMPORTANCE The optimal growth temperatures of hyperthermophilic archaea accelerate DNA decomposition, which is expected to make DNA repair especially important for their genetic stability, yet these archaea lack certain broadly conserved types of DNA repair proteins. In this study, the genome of the extreme thermoacidophile Sulfolobus acidocaldarius was found to be remarkably stable, accumulating few mutations in many (though not all) laboratory manipulations and in natural populations. Furthermore, all the genetic processes that were inferred to diversify these genomes also operate in mesophilic bacteria and eukaryotes. This suggests that a common set of mechanisms produces most of the genetic variation in all microorganisms, despite the fundamental differences in physiology, DNA repair systems, and genome structure represented in the three domains of life.

A baseline study of vicine–convicine levels in faba bean (Vicia faba L.) germplasm

2013 ◽  
Vol 11 (3) ◽  
pp. 250-257 ◽  
Author(s):  
Khalil Khamassi ◽  
Fayçal Ben Jeddi ◽  
Doug Hobbs ◽  
Jose Irigoyen ◽  
Fred Stoddard ◽  
...  
Keyword(s):  
Plant Breeding ◽  
Faba Bean ◽  
Screening Method ◽  
Wild Type ◽  
Faba Beans ◽  
Collaborative Plant Breeding ◽  
Nutritional Compounds ◽  
The Uk ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Plant Breeding Programme

Vicine and convicine are anti-nutritional compounds that accumulate in the cotyledons of faba beans. When humans consume beans with high levels of these compounds, it can cause a condition called favism in individuals harbouring a deficiency in the activity of their glucose-6-phosphate dehydrogenase. When faba beans are used in animal feeds, there can be effects on performance. These concerns have resulted in increasing interest within plant breeding in developing low vicine and convicine faba bean germplasm. In order to facilitate this objective, we developed a rapid and robust screening method for vicine and convicine, capable of distinguishing between faba beans that are either high (wild type) or low in vicine and convicine. In the absence of reliable commercial reference materials, we report an adaptation of a previously published method where a biochemical assay and spectral data were used to confirm the identity of our analytes, vicine and convicine. This method could be readily adopted in other facilities and open the way to the efficient exploitation of diverse germplasm in regions where faba beans play a significant role in human nutrition. We screened a collection of germplasm of interest to a collaborative plant breeding programme developing between the National Institute for Agricultural Botany in the UK and L'Institut Nationale d'Agronomie de Tunisie in Tunisia. We report the results obtained and discuss the prospects for developing molecular markers for the low vicine and convicine trait.

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