Gametic and somatic embryogenesis through in vitro anther culture of different Citrus genotypes

Abstract: In vitro tissue culture represents a useful technique for advancing Citrus breeding and propagation. Among in vitro regeneration systems, anther culture is commonly used to produce haploids and doubled haploids for a fast-track producing homozygous lines, in comparison with the traditional self-pollination approach, which involves several generations of selfing. In addition, anthers culture can produce somatic embryos that can also be used for clonal propagation. In this study, two thermal shocks were applied to the anthers of six Citrus genotypes (two clementine and four sweet oranges), just after they were put in culture. The response obtained was different depending on the genotype: both clementines, namely Hernandina and Corsica, produced homozygous and triploid regenerants (microspore-derived embryos), whereas all of the analyzed regenerants from sweet oranges, three cultivars of Tarocco and Moro, produced heterozygous and diploid regenerants similar to the parental genotypes (somatic embryos)

Effect of polyamines on in vitro anther culture of Citrus clementina Hort. ex Tan

The improvement of the induction rate in Citrus anther culture is important for taking practical advantage of the haploid potential in breeding. The influence of polyamines on anther culture of Citrus clementina, cv Nules, with particular attention to the free, soluble and insoluble- conjugated polyamine levels, has been investigated. Putrescine, spermidine and putrescine plus spermidine, were added to the standard induction medium. Before culture, spermidine was the most abundant among the free polyamines detected in anthers. The exogenous supply of either putrescine or spermidine, either independently or combined, effected greater uptake and accumulation of polyamines. The addition of 2 mM spermidine to the medium stimulated gametic embryogenesis in clementine Nules, whereas putrescine did not influence embryo production. Regenerants were mostly tri-haploids; a few doubled-haploids and no haploid plants were obtained