RESUMO
Broccoli (Brassica olearecea var. italica) is a cole crop grown for its floral heads and stalks. It is rich in bioactive chemicals good for human health. Broccoli has been consumed as a vegetable since Roman times, but its production and consumption have increased significantly over the past few decades. Breeders try to develop new broccoli varieties with high yield, improved quality, and resistance to biotic and abiotic stresses. Almost all new broccoli varieties are F1 hybrids. Development of inbred broccoli lines that can be used as parents in hybrid production is a time-consuming and difficult process. Haploidization techniques can be utilized as a valuable support in broccoli breeding programs to speed up the production of genetically pure genotypes. Haploid plants of broccoli can be produced from immature male gametophytes via anther and microspore cultures with similar success rates. The most important parameters affecting the success of haploidization in broccoli are the genetic background (genotype) and the developmental stage of the microspores. Broccoli genotypes differ in their responses to androgenesis induction. The highest androgenesis response could be induced from microspores in late uninucleate and early binucleate stages. Recovery of diploid broccoli plants from haploids is possible via spontaneous and induced doubling. Doubled haploid (DH) broccoli lines are considered to be fully homozygous. Therefore, the production of DH lines is an alternative way to obtain pure inbred lines that can be utilized as parents in the development of new F1 hybrid varieties showing high levels of heterosis, high-quality heads, and uniform harvestable crop. We are using an anther culture-based haploid plant production system to develop DH broccoli lines in our broccoli breeding program. DH broccoli lines are produced from different genetic backgrounds within a year and handed to broccoli breeders.
Assuntos
Brassica/crescimento & desenvolvimento , Brassica/genética , Melhoramento Vegetal/métodos , Aclimatação/genética , Brassica/fisiologia , Produtos Agrícolas/genética , Produtos Agrícolas/crescimento & desenvolvimento , Meios de Cultura/química , Diploide , Citometria de Fluxo , Flores/genética , Flores/crescimento & desenvolvimento , Haploidia , Homozigoto , Vigor Híbrido/genética , Biologia Molecular/métodos , Ploidias , Pólen/genética , Pólen/crescimento & desenvolvimento , Regeneração/genética , Técnicas de Cultura de TecidosRESUMO
Leek (A. ampeloprasum L.) is an economically important vegetable crop from Alliaceae family. It is a non-bulb forming biennial species grown for its pseudostem and leaves. Leek is a tetraploid with one of the largest genomes known among cultivated plant species. It has enormous economic importance all around the world for many purposes such as vegetable, medicinal herb, and food seasoning. Production and consumption of leek is in rise all around the world and breeders are trying to develop new F1 hybrid varieties with desired agronomical traits. Although self-compatible, leek shows high tendency toward outcrossing and display severe inbreeding depression when selfed with its own pollen. Therefore, inbred development through classical breeding techniques is very difficult in this crop. Traditional leek genotypes are highly heterozygous, open pollinated varieties. There is a high demand for F1 hybrid varieties with resistance to biotic and abiotic stresses and high-quality plants. Our group is trying to incorporate gynogenesis-based doubled haploid technology to leek improvement programs. Over the years, many experiments were carried out to determine the gynogenic potential of donor leek genotypes of different genetic backgrounds in different induction media. Here, we report a protocol allowing production of green gynogenic leek plants via single step culture of unopened flower buds. Ploidy levels of gynogenic regenerants are determined by flow cytometry analysis. A majority of the gynogenic leek regenerants produced survived well in vivo.
Assuntos
Allium/crescimento & desenvolvimento , Allium/genética , Cromossomos de Plantas , Gametogênese Vegetal , Melhoramento Vegetal/métodos , Flores/genética , Flores/crescimento & desenvolvimento , Haploidia , Técnicas In Vitro , Fenótipo , Pólen/genética , Pólen/crescimento & desenvolvimentoRESUMO
The freezing tolerance of 38 independent transgenic potato lines derived from the cultivar Desiree was tested in vitro using plantlets. The lines were transgenic for the DREB1A gene under control of the rd29A promoter, both of which were derived from Arabidopsis thaliana. The level of damage caused by freezing varied significantly among the transgenic clones and a non-transgenic control (cv. Desiree). Phenotypic evaluation indicated that the variable responses to freezing were attributable to genotypic variation, but freezing tolerance was not dependent on the number of insertions. Northern blot analysis using a DREB1A cDNA probe revealed high levels of DREB1A expression among the transgenic clones during the initial cold exposure at 4 degrees C (after 2 h) and in the early stages of freezing (-20 degrees C, 1-10 min). Furthermore, a linear correlation was detected between the level of expression and the phenotypic response for all lines except D138. Thus, in the case of potato, a significant increase in freezing tolerance was observed in vitro on a small scale following the introduction of rd29A::DREB1A. Additional testing will show whether this strategy can be used for tolerance breeding in potato and to increase the freezing tolerance of other agriculturally important crops.