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Breen Templeton posted an update 6 months ago
In this chapter, we present a list of species (and few interspecific hybrids) where haploids and/or doubled haploids have been published, including the method by which they were obtained and the corresponding references. This list is an update of the compilation work of Maluszynski et al. published in 2003, including new species for which protocols were not available at that time, and also novel methodologies developed during these years. The list includes 383 different backgrounds. In this book, we present full protocols to produce DHs in 43 of the species included in this list. In addition, this book includes a chapter for one species not included in the list. This makes a total of 384 species where haploids and/or DHs have been reported up to date.Manifold and diverse applications of doubled haploid (DH) plants have emerged in academy and in the plant breeding industry since the first discovery of a haploid mutant in the Jimson Weed (Datura stramonium), followed by the first reports about anther culture in the same species, maternal haploids by wide crosses in tobacco (Nicotiana tabacum L.) and barley (Hordeum vulgare L.), interspecific hybridization, ovary culture (gynogenesis), isolated microspore culture, and more recently the CENH3 approach in thale cress (Arabidopsis thaliana L.) and other species. Research and development efforts were and are still significant in both user groups. Luckily, often academic and industrial partners cooperate in challenging and sometimes voluminous projects worldwide. Not only to develop innovative DH protocols and technologies per se, but also to exploit the advantages of DH plants in a huge variety of research and development experiments. This review concentrates not on the DH technologies per se, but on the application of DHs in plant-related research and development projects.Doubled haploids (DH) have become a powerful tool to assist in different basic research studies, and also in applied research. The principal (but not the only) and routine use of DH by breeding companies is to produce pure lines for hybrid seed production in different crop species. Several decades after the discovery of haploid inducer lines in maize and of anther culture as a method to produce haploid plants from pollen precursors, the biotechnological revolution of the last decades allowed to the development of a variety of approaches to pursue the goal of doubled haploid production. find more Now, it is possible to produce haploids and DHs in many different species, because when a method does not work properly, there are several others to test. In this chapter, we overview the currently available approaches used to produce haploids and DHs by using methods based on in vitro culture, or involving the in vivo induction of haploid embryo development, or a combination of both.Microspores, with a haploid number of chromosomes, are destined to produce the male gametophyte, which hosts the male gametes that fertilize the female egg cell. During microsporogenesis, a particular stage of development is amenable to be switched to undergo embryogenesis and developed into a haploid plant. By doubling the chromosomes, a doubled haploid plant, homozygous for all the gene loci, is produced. These plants are useful to study the expression of recessive genes and in plant breeding as a rapid pathway to achieve homozygosity.Here we present an optimized protocol for in vitro embryo formation and plant regeneration through anther culture of the Mexican husk tomato (Physalis ixocarpa Brot.). This protocol relies on the application of an anther thermal shock at a specific developmental stage prior to the in vitro culture, ensures embryo formation from anthers without callus formation, and allows spending less time to regenerate doubled haploid complete plants. This protocol has been used for different cultivars of Physalis ixocarpa (Chapingo, Rendidora, Puebla, Arandaz, Manzano, Tamazula, Salamanca, and Milpero), and also for two wild-type accessions, all of them cultivated in Mexico. Chapingo cultivar responded with the highest percentage of androgenesis on the embryo induction medium (EIM).Anther culture provides a tool to produce haploid lines from cultivated potato (Solanum tuberosum L.), which has a tetraploid (2n = 4x = 48) genome constitution. Shoot regeneration via direct embryogenesis in anther culture procedure is preferred to produce dihaploid (2n = 2x = 24) potato lines, which can be applied in breeding of potato varieties. The anther culture protocol described in the present chapter can be conducted not only in cultivated potato (S. tuberosum) but also in other genetically related potato species.Haploids are plants with gametophytic chromosome number, which upon chromosome duplication results in production of doubled haploids (DHs). There are several methods to obtain haploids and DHs, of which in vitro anther culture is the most effective and widely used method in tobacco. The production of haploids and DHs through androgenesis allows for a single-step development of complete homozygous lines from heterozygous genotypes, shortening the time required to produce homozygous genotypes in comparison to the conventional breeding scheme. The DH development process comprises two main steps induction of androgenesis and duplication of the haploid genome. The critical stages of DH protocol in tobacco are determining the bud stage for anther culture, pretreatment, anther culture media, detection and identification of haploids, and chromosome doubling. Here we present an efficient anther culture protocol to get haploids and DHs in flue-cured virginia (FCV) tobacco. This optimized protocol can be used as a potential tool for generation of haploids and DHs for genetic improvement of tobacco.Peppers have a prominent role in traditional cuisine of many different countries all around the world. This is why pepper is one of the most important crops worldwide. Production of doubled haploid (DH) pepper plants has been assessed by different approaches, but at present, the most efficient and universal method is by far anther culture, based on the use of the Dumas de Vaulx et al. protocol published in 1981, and adapted to the particularities of each specific pepper background. In this chapter, we present a method to produce pepper DHs by anther culture, based on the Dumas de Vaulx et al. protocol, but including a number of modifications which, in our experience, allow for a more efficient production DH plants in different pepper genotypes.