Search results for "Haploidy"
showing 10 items of 25 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…
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…
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).
First stages of microsporere programming to embryogenesis through anther culture in Prunus armeniaca L.
2011
6 páginas, 3 figuras, 2 tablas -- PAGS nros. 152-157
Cell volume homeostatically controls the rDNA repeat copy number and rRNA synthesis rate in yeast
2021
[Abstract] The adjustment of transcription and translation rates to the changing needs of cells is of utmost importance for their fitness and survival. We have previously shown that the global transcription rate for RNA polymerase II in budding yeast Saccharomyces cerevisiae is regulated in relation to cell volume. Total mRNA concentration is constant with cell volume since global RNApol II-dependent nascent transcription rate (nTR) also keeps constant but mRNA stability increases with cell size. In this paper, we focus on the case of rRNA and RNA polymerase I. Contrarily to that found for RNA pol II, we detected that RNA polymerase I nTR increases proportionally to genome copies and cell s…
Gametic embryogenesis and haploid technology as valuable support to plant breeding
2011
Plant breeding is focused on continuously increasing crop production to meet the needs of an ever-growing world population, improving food quality to ensure a long and healthy life and address the problems of global warming and environment pollution, together with the challenges of developing novel sources of biofuels. The breeders' search for novel genetic combinations, with which to select plants with improved traits to satisfy both farmers and consumers, is endless. About half of the dramatic increase in crop yield obtained in the second half of the last century has been achieved thanks to the results of genetic improvement, while the residual advance has been due to the enhanced managem…
Production of Haploid and Doubled Haploid Lines in Nut Crops: Persian Walnut, Almond, and Hazelnut
2021
This chapter deals with induction of haploidy via parthenogenesis in Persian walnut and via microspore embryogenesis in almond and hazelnut. Haploid induction through in situ parthenogenesis using pollination with irradiated pollen to stimulate the embryogenic development of the egg cell, followed by in vitro culture of the immature haploid embryos. Microspore embryogenesis allows the induction of immature pollen grains (microspores), to move away from the normal gametophytic developmental route in the direction of the sporophytic one, yielding homozygous organisms (embryos in this case). Unlike other fruit crops (such as Citrus), regeneration of entire plants has not yet been obtained in o…