Search results for "haploid"
showing 10 items of 51 documents
Microspore Embryogenesis Through Anther Culture in Citrus clementina Hort. ex Tan.
2016
Anther culture is a biotechnological method that allows to obtain, in one step, homozygous plants, very important to plant breeding, due to their numerous applications in mutation research, selection, genome sequencing, genetic analysis, and transformation. To induce the microspores, i.e., the immature male gametes, to switch from the normal gametophytic pathway to the sporophytic one, it is necessary to submit them to a type of stress, such as high or low temperature, starvation, or magnetic field. Stress can be applied to the donor plants and/or the fl oral buds or the anthers or the isolated microspores, before or during the culture. In this chapter, the protocol to induce gametic embryo…
Microspore embryogenesis induced through in vitro anther culture of almond (Prunus dulcis Mill.)
2016
Anther culture is one of the most widely used methods to induce gametic embryogenesis. The aim of this investigation was to induce microspore embryogenesis in almond (Prunus dulcis Mill.), through this technique. Anthers were cultured at the vacuolated developmental stage, and seven cultivars, two culture media and two temperature treatments were assessed. Although evidence of the microspore induction was observed in all the genotypes and treatments tested (symmetrical nucleus division and multinucleated structures), calli were produced merely by anthers cultured in the medium P and the regeneration of embryos was detected only in anthers of the cultivars Filippo Ceo, Lauranne and Genco, pl…
Gametic embryogenesis through isolated microspore culture in Corylus avellana L.
2015
Haploid technology is a valuable plant breeding tool for obtaining homozygosity particularly in woody plants. Hazelnut, the world’s sixth ranking nut tree crop is a monoecious, anemophilous species. It is characterized by a sporophytic incompatibility system that prevents production of homozygous plants with conventional methods, involving several self-pollination cycles. In this study, gametic embryogenesis, in particular isolated microspore culture, was tried with five genotypes. Two culture media were tested and four temperature stress treatments were applied to the isolated microspores that were cultivated at the vacuolated developmental stage. To our knowledge, this is the first report…
Cytological and molecular characterization of three gametoclones of Citrus clementina
2013
Abstract Background Three gametoclonal plants of Citrus clementina Hort. ex Tan., cv. Nules, designated ESP, FRA, and ITA (derived from three labs in Spain, France, and Italy, respectively), were selected for cytological and molecular characterization in order to elucidate genomic rearrangements provoked by haploidization. The study included comparisons of their ploidy, homozygosity, genome integrity, and gene dosage, using chromosome counting, flow cytometry, SSR marker genotyping, and array-Comparative Genomic Hybridization (array-CGH). Results Chromosome counting and flow cytometry revealed that ESP and FRA were haploid, but ITA was tri-haploid. Homozygous patterns, represented by a sing…
Doubled haploid production in onion (Allium cepa L.): from gynogenesis to chromosome doubling
2020
Bulb onion (Allium cepa L.) is an allogamous diploid (2n = 16) important for its culinary uses, nutritional value, and medicinal benefits. Despite its economic importance, onion yields and bulb quality are declining, emphasizing the need for new and improved strategies for maintaining and enhancing overall crop quality. Development of inbred lines in onion through traditional breeding is often difficult due to its biennial life cycle, inbreeding depression, and comparatively high heterozygosities. Moreover, genetic research in onion has been hampered by large nuclear genome size. In this regard, gynogenic doubled haploids promise several advantages over inbred lines in support of onion bree…
Kinetics of the early development of uniparental human haploid embryos
2016
Objective: To describe morphokinetically the early development of human haploid parthenotes and androgenotes and to compare them with euploid embryos. Design: Experimental study of kinetics. Setting: University-affiliated private fertility center. Patient(s): Experimental haploid parthenotes and androgenotes. Intervention(s): Kinetic study of early development (up to eight cells) of 8 parthenotes, 10 androgenotes, and 20 euploid embryos. Main Outcome Measure(s): Timing of the first seven cleavages determined according to embryo origin, then calculation of the duration of the second and third cell cycles (cc2 and cc3) of whole embryos and individual cells. Result(s): Parthenotes and androgen…
Doubled haploid production in fruit crops
2006
The interest of fruit breeders in haploids and doubled haploids (DH), lies in the possibility of shortening the time needed to produce homozygous lines compared to conventional breeding. Haplo-diploidization through gametic embryogenesis allows single-step development of complete homozygous lines from heterozygous parents. In a conventional breeding programme, a pure line is developed after several generations of selfing. With fruit crops, characterized by a long reproductive cycle, a high degree of heterozygosity, large size, and, sometimes, self-incompatibility, there is no way to obtain haploidization through conventional methods. This paper reviews the current status of research on doub…
Single-agent GvHD prophylaxis with tacrolimus after post-transplant high-dose cyclophosphamide is a valid option for haploidentical transplantation i…
2017
Eighty-one patients with high-risk hematological malignancies received unmanipulated haploidentical stem cell transplants (haploSCT) using the same protocol at four Spanish institutions. The conditioning regimen was thiotepa, busulfan and fludarabine; following bone marrow or peripheral blood infusion. GvHD prophylaxis with high-dose cyclophosphamide on days +3 and +4, and IV tacrolimus from day +5 was administered. 62% were in complete remission, 17% had received previous allogeneic SCT and 44% had a high-very high refined disease risk index. One patient had primary graft failure and three more died before +21. The median days to neutrophil and platelet recoveries were +18 and +23, respect…
Prospective Randomized Study Comparing Myeloablative Unrelated Umbilical Cord Blood Transplantation versus HLA-Haploidentical Related Stem Cell Trans…
2020
In this prospective randomized study, we compared the outcomes of single-unit umbilical cord blood transplantation (UCBT) and unmanipulated haploidentical stem cell transplantation (haplo-SCT) with post-transplantation cyclophosphamide (PTCy) in adults with hematologic malignancies. All patients received a myeloablative conditioning (MAC) regimen consisting of thiotepa, busulfan, and fludarabine, with antithymocyte globulin (ATG) added for UCBT recipients. Nineteen patients were randomized to UCBT and the other 26 to haplo-HSCT. Four patients (15%) allocated to the haplo-HSCT arm lacked a suitable donor and were crossed over to the UCBT arm. Finally, 23 underwent UCBT and 22 underwent haplo…
Microspore Embryogenesis in Citrus
2021
This chapter deals with microspore embryogenesis in Citrus. Microspore embryogenesis allows to induce immature gametes (microspores) and to deviate them, in this case, the male one, from the normal gametophytic developmental route in the direction of the sporophytic one, yielding homozygous organisms (embryos and plants).