Anatomical and biochemical characterization of the calcium effect on eucalyptus urophylla callus morphogenesis in vitro

Calcium chloride concentrations from 0.0 to 12.12 mM were added to the culture medium and calcium content in calluses were determined directly by X-ray fluorescence spectrometry, a non-destructive method, allowing the processing of the same tissue for histological analysis. A multivariate statistical analysis (PCA - Principal Components Analysis) grouped the treatments into 5 blocks and indicated the most responsive group. Lack of calcium supply caused a complete absence of a morphogenic process and tissue collapse. An increase in calcium concentration gave higher total protein and sugar contents, an increase in peroxidase specific activity and changes in the histological characteristics. It was possible to verify that calcium stimulated globular somatic embryo formation at concentration of 6.62 mM.

Ultrastructural analysis of in vitro direct and indirect organogenesis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo das poliaminas na morfogênese in vitro de Hemerocallis sp.

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito de poliaminas exógenas no crescimento inical in vitro e nos teores de fenóis, poliaminas e atividade da peroxidase em Aloe vera (L.) Burm.

Lateral shoots of the Aloe vera (L.) Burm. cultivated in vitro, without addition vegetal regulators, for 90 days, were inoculated in MS culture-medium, containing or not spermine and/or spermidine. After 30 days of cultivation, the plants were submitted to biochemical analysis together with micropropagated plants - that were under in vitro cultivation for 90 days - (denominated as characterization), and matrix plants (in vivo). The levels of free polyamines, total phenols, total flavonoids, and the activity of peroxidase were evaluated in the biochemical analyses. The exogenous application of spermidine have promoted large number of shoots. Spermidine and spermine have promoted, when associated, an increase in the number of shoots as well as an increase of the contents of putrescine and and flavonoids. The putrescine has presented the most significant alterations, enabling to be utilized as marker of morphogenesis in the micropropagated Aloe vera. Tissues under active growth have presented high activity of peroxidase as well as those with greater rate of oxidation. In these tissues, there were noticed also higher contents of total flavonoids, indicating the need of antioxidative compounds. The action of polyamines jointly tseemed to be benefic for the shooting of micropropagated Aloe vera.