Effect of water stress and heavy metals on induction of somatic embryogenesis in wheat leaf base cultures.

In vitro cultures of plant tissues are known to mimic the response of field-grown plants when subjected to stress treatments. This investigation on Triticum aestivum explores the effect of drought stress on somatic embryogenesis and endogenous proline content. Leaf bases were cultured on MS medium supplemented with 2,4-D (10 microM) and different concentrations of PEG (2.5, 5, 7.5%) or mannitol (0.25 and 0.5 M) and also subjected to different periods of aerial drying in the laminar flow for one-day and subsequently transferred to MS basal medium. PEG treatment induced a high percentage (up to 50%) of embryoid formation. However, with mannitol and aerial drying, percentage of embryoid formation decreased with increasing concentrations and duration. After ten days, the endogenous proline content of explants treated with different concentrations of PEG, mannitol and different durations of aerial drying increased with increasing concentration and increasing duration of the treatment, thus, corroborating the role of proline as an osmolyte during stress conditions. Similarly, addition of metals such as cadmium and cobalt caused a reduction in percentage explants depicting embryogenesis. However, when cadmium was employed alone, 22% explants displayed somatic embryogenesis as compared to 54% in 2,4-D treated cultures.

Agrobacterium rhizogenes vs auxinic induction for in vitro rhizogenesis of Prosopis chilensis and Nothofagus alpina

The induction and improvement of in vitro rhizogenesis of microshoots of Prosopis chilensis (Mol.) Stuntz and Nothofagus alpina (Poep. et Endl. Oerst.) were compared using Agrobacterium rhizogenes (Ar) versus indole-3-butyric acid (IBA) in the culture media. Microshoots of P. chilensis (1-2 cm length), coming from in vitro grown seedlings, were cultivated in a modified Broadleaved Tree Medium (BTMm) containing half salt concentration of macronutrients and 0.05 mg x L(-1) benzilaminopurine (BAP). After 30 days, microshoots with 2-4 leaves were selected and cultured in BTMm-agar in presence or abscense of Ar and in combination with IBA. For N. alpina, the apical shoots with the first 2 true leaves, from 5 weeks old seedlings, were cultured in the abovementioned medium, but with 0.15 mg x L(-1) of BAP. After 2 months, microshoots with 2-3 leaves were selected and cultured in BTMm-agar, supplemented with 5 mg x L(-1) IBA or in liquid BTMm on perlite and, in the presence or absence of A. rhizogenes (Ar) and in combination with 3 mg x L(-1) IBA. Rooting in P. chilensis reached 100.0% when Ar infection was produced in the presence of IBA, increasing both, the number and dry weight of roots. In N. alpina, 90.0% of rooting efficiency was obtained when Ar infection was produced in liquid culture and in the absence of auxin.

Contribuição ao estudo de Laurus nobilis l. (louro) / Contribution to the study of Laurus nobilis l. (louro)

Realizou-se a caracterização química, macroscópica e microscópica das folhas de Laurus nobilis L. (louro),com a finalidade de contribuir para a sua identificação e controle de qualidade, já que é utilizado pela população como condimento e fitoterápico. Na caracterização química, ralizada segundo as técnicas da Farmacopéia Brasileira,1977 e Instituto Adolfo Lutz, 1976, determinou-se a umidade, resíduo mineral fixo, extratos alcoólico, aquoso,etéreo e seco, nitrogênio total, proteína bruta e fibra bruta....