Induction of somatic embryogenesis in immature seeds of guavatree cv. Paluma Indução de embriogênese somática em sementes imaturas de goiabeira cv. Paluma

The biotechnological techniques may help solve many problems of guava culture, such as the high perishability of fruits. Somatic embryogenesis can generate highly multiplicative cell cultures and with high regenerative potential, serving as basis for genetic transformation. The aim of this work was to obtain somatic embryogenesis of guava (Psidium guajava L.) cv. Paluma. Immature seeds were used, and they were inoculated in MS environment containing 400 mg L-1 of L-glutamine, 100 mg L-1 myo-inositol, 60 g L-1 sucrose, 100 mg L-1 ascorbic acid and supplemented with different types and concentrations of growth regulators. Embryogenic callus appeared after 37 days of culture in an environment containing 1.0 mg L-1 2.4-D + 2.0 mg L-1 2-ip, in 7% of the explants. After 65 days of culture, the treatment containing 0.5 mg L-1 CPA showed 20% of explants with direct embryos, while the treatment with 1 mg L-1 had 14% of explants with direct embryos and 7% of explants with embryogenic callus. In 66.6% of embryos regenerated with 0.5 mg L¹ CPA there was the formation of secondary embryos. The use of IASP and BAP, aiming embryogenesis proliferation, led to an increase in the cellular proliferation, but calli apparently lost their embryogenic potential.<br>As técnicas biotecnológicas podem ajudar a solucionar alguns problemas do cultivo da goiabeira, como o alto perecimento dos frutos. A embriogênese somática pode gerar culturas de células altamente multiplicativas e com alto poder regenerativo, sendo base para processos de transformação genética. O objetivo deste trabalho foi obter embriogênese somática de goiabeira (Psidium guajava L.) cv. Paluma. Foram utilizadas sementes imaturas, que foram inoculadas em meio MS contendo 400 mg L-1 de L-glutamina, 100 mg L-1 de mioinositol, 60 g L-1 de sacarose, 100 mg L-1 de ácido ascórbico, suplementado com diferentes tipos e concentrações de reguladores de crescimento. Calo embriogênico surgiu após 37 dias de cultivo em meio contendo 1,0 mg L-1 de 2,4-D + 2,0 mg L-1 de 2-ip, em 7% dos explantes. Após 65 dias de cultivo, o tratamento com 0,5 mg L-1 de CPA apresentou 20% dos explantes com embriões diretos, enquanto o tratamento com 1 mg L-1 teve 14% dos explantes com embriões diretos e 7% dos explantes com calo embriogênico. Em 66,6% dos embriões regenerados com 0,5 mg L-1 de CPA, houve formação de embriões secundários. O uso de IASP e BAP, visando à proliferação da embriogênese, levou a aumento de proliferação celular, mas os calos aparentemente perderam o potencial embriogênico

Involvement of Plant Hormones and Plant Growth Regulators on in vitro Somatic Embryogenesis

In spite of the importance attained by somatic embryogenesis and of the many studies that have been conducted on this developmental process, there are still many aspects that are not fully understood. Among those features, the involvement of plant hormones and plant growth regulators on deTermining the conversion of somatic onto embryogenic tissues, and on allowing progression and maturation of somatic embryos, are far away from being completely comprehended. Part of these difficulties relies on the frequent appearance of contradictory results when studying the effect of a particular stimulus over a specific stage in somatic embryogenesis. Recent progress achieved on understanding the interaction between exogenously added plant growth regulators over the concentration of endogenous hormones, together with the involvement of sensitivity of the tissues to particular hormone groups, might help clarifying the occurrence of divergent patterns in somatic embryogenesis, and in tissue culture in general. The aspects described above, emphasizing on the effect of the concentration of plant hormones and of the addition of plant growth regulators during the different phases of somatic embryogenesis, will be reviewed in this paper. Citations will be limited to review articles as much as possible and to individual articles only in those cases in which very specific or recent information is presented.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro para Investigaciones en Granos y Semillas (CIGRAS