Search results for "homozygosity"
showing 10 items of 42 documents
Microspore embryogenesis inCitrusand other fruit crops
2017
Conventional methods, involving several generations of selfing, are not applicable to produce homozygous lines in Citrus as well as in the other fruit crops, due to the high heterozygosity of the genomes, the long duration of the generation cycle, the large size, and, often, the self-incompatibility. For this reason, there is no different way to obtain homozygosity in this kind of plants than âgametic embryogenesisâ that allows the development of haploids (Hs, plants with gametophytic chromosome number) and doubled haploids (DHs, haploids that have undergone chromosome duplication) from heterozygous parents in a single step. Therefore, gametic embryogenesis is increasingly object of res…
Gametic embryogenesis through isolated microspore culture in mandarin (Citrus reticulata Blanco), Mandarino Tardivo Di Ciaculli: effect of meta-Topol…
2016
Haploid technology, allowing the single-step development of complete homozygous genotypes from heterozygous plants through gametic embryogenesis, has already an enormous impact on breeding programs of many important crops. Microspore embryogenesis can be carried out through in vitro culture of anther or isolated microspore. Experiments have been carried out via isolated microspore culture in Citrus reticulata (Blanco), Mandarino Tardivo di Ciaculli, investigating the influence of two culture media, of two plant growth regulator types and of two temperature treatments applied before the culture or just after the culture. After ten months of culture, for all the media tested, different struct…
STUDY ON GAMETIC EMBRYOGENESIS VIA IN VITRO ANTHER AND ISOLATED MICROSPORE CULTURE IN FRUIT CROPS
2014
Fruit breeding is mainly based on both conventional (hybridization, mutation and selection) or biotechnological methods (somatic hybridization, genetic transformation and haploid production). The genetic improvement through the conventional methods is limited by many factors such as fruit trees long juvenile period, high heterozygosity, large size and sexual incompatibility. Haploids and doubled haploids, obtained through gametic embryogenesis have a potential use in fruit crops genetic improvement. The change of the microspores fate from the normal gametopytic pathway towards the sporophytic induction is affected by numerous factors. Genotype, medium composition and stress were considered …
Genome-wide scan for Runs of Homozygosity in Valle del Belice sheep
2017
The current availability of very large numbers of single nucleotide polymorphisms (SNPs) throughout the genome makes these markers particularly suitable for the detection of genomic regions where a reduction in heterozygosity occurred and offers new opportunities to improve the accuracy of inbreeding (F) estimates. Runs of homozygosity (ROH) are contiguous lengths of homozygous segments of the genome where the two haplotypes inherited from the parents are identical. Here, we investigated the occurrence and the distribution of ROH in medium-density SNP genotypes (~ 50 000) in order to characterize autozygosity in 512 individuals of Valle del Belice sheep and identify the regions of the genom…
Genome-wide analyses reveal population structure and identify candidate genes associated with tail fatness in local sheep from a semi-arid area.
2021
Abstract Under a climate change perspective, the genetic make-up of local livestock breeds showing adaptive traits should be explored and preserved as a priority. We used genotype data from the ovine 50 k Illumina BeadChip for assessing breed autozygosity based on runs of homozygosity (ROH) and fine-scale genetic structure and for detecting genomic regions under selection in 63 Tunisian sheep samples. The average genomic inbreeding coefficients based on ROH were estimated at 0.017, 0.021, and 0.024 for Barbarine (BAR, n = 26), Noire de Thibar (NDT, n = 23), and Queue fine de l'Ouest (QFO, n = 14) breeds, respectively. The genomic relationships among individuals based on identity by state (I…
Runs of homozygosity in the Italian goat breeds: impact of management practices in low-input systems
2021
Abstract Background Climate and farming systems, several of which are considered as low-input agricultural systems, vary between goat populations from Northern and Southern Italy and have led to different management practices. These processes have impacted genome shaping in terms of inbreeding and regions under selection and resulted in differences between the northern and southern populations. Both inbreeding and signatures of selection can be pinpointed by the analysis of runs of homozygosity (ROH), which provides useful information to assist the management of this species in different rural areas. Results We analyzed the ROH distribution and inbreeding (FROH) in 902 goats from the Italia…
Ploidy manipulation for genetic improvement in some Mediterranean fruit crops
2017
Plant breeding is focused on selection of new genotypes with improved traits. Conventional methods based on hybridization and those based on biotechnology (somatic hybridization, genetic transformation, ploidy manipulation, etc.) are used to create novel genetic variations. Biotechnology provides powerful tools for plant breeding, for instance, haploid technology allows achievement of homozygous lines from heterozygous parents in one step, which reduces significantly the time required by conventional methods. Concerning woody species, characterized by self-incompatibility, long juvenile period and high degree of heterozygosity, this technique is the only way to get homozygous lines. Haploid…
A Combined Multi-Cohort Approach Reveals Novel and Known Genome-Wide Selection Signatures for Wool Traits in Merino and Merino-Derived Sheep Breeds.
2019
Merino sheep represents a valuable genetic resource worldwide. In this study, we investigated selection signatures in Merino (and Merino-derived) sheep breeds using genome-wide SNP data and two different approaches: a classical F-ST-outlier method and an approach based on the analysis of local ancestry in admixed populations. In order to capture the most reliable signals, we adopted a combined, multi-cohort approach. In particular, scenarios involving four Merino breeds (Spanish Merino, Australian Merino, Chinese Merino, and Sopravissana) were tested via the local ancestry approach, while nine pair-wise breed comparisons contrasting the above breeds, as well as the Gentile di Puglia breed, …
Genomic inbreeding estimation in small populations: evaluation of runs of homozygosity in local cattle breeds
2015
The availability of high throughput genotyping has facilitated the quantification of inbreeding by genomic markers in farm animals. Run of homozygosity (ROH) are contiguous lengths of homozygous genotypes and represent an estimate of the degree of autozygosity at genome-wide level. The current study aims to quantify the genomic inbreeding derived from ROH (FROH) in three Italian local cattle breeds. Individuals of Cinisara (71), Modicana (72), Reggiana (168) were genotyped with the 50K v2 Illumina BeadChip. Genotypes from 96 animals of the Italian Holstein cattle breed were included in the analysis. The following criteria were used to define a ROH: two missing SNPs; one heterozygous SNP; mi…
Data from: No inbreeding depression but increased sexual investment in highly inbred ant colonies
2012
Inbreeding can lead to the expression of deleterious recessive alleles and to a subsequent fitness reduction. In Hymenoptera, deleterious alleles are purged in haploid males moderating inbreeding costs. However, in these haplo-diploid species, inbreeding can result in the production of sterile diploid males. We investigated the effects of inbreeding on the individual and colony level in field colonies of the highly inbred ant Hypoponera opacior. In this species, outbreeding winged sexuals and nest-mating wingless sexuals mate during two separate reproductive periods. We show that regular sib-matings lead to high levels of homozygosity and the occasional production of diploid males, which sp…