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.