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Somatic embryogenesis in Agave tequilanaWeber var. Azul was affected by the interaction between the light regimes applied during the induction phase and the expression phase. When embryogenic calli was exposed to white or red light during the expression phase, an average of two germinated embryos per explant was obtained regardless of the light treatment used for callus induction. Conversely, the highest number of germinated embryos, an average of 18 per explant, was obtained when applying either white or red light during the induction phase and then wide-spectrum light during the expression phase. Culture medium had also a great influence in this process, with embryo germination being reduced by up to 70%, depending on the light treatment, when using Schenk and Hildebrandt (SH) medium instead of Murashige and Skoog (MS) medium.

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A biolistic protocol for the stable genetic transformation of the hardwood tree Paulownia elongata was developed. Leaf explants were bombarded using the PDS-1000/He system with plasmid pBI121. The introduced DNA contained the b-glucuronidase (GUS) reporter gene and neomycin phosphotransferase (nptII) as a selection marker. Transformed calli were induced and selected on medium supplemented with 50 mg L -1 kanamycin, and transgenic plants were regenerated through indirect organogenesis. Complete plants were successfully transferred to soil and established under greenhouse conditions. Different helium pressures and explant positions were used and the transformation frequency was calculated. Optimal conditions for genetic transformation were bombardment of the abaxial leaf surface at a pressure of 450 psi. The integration of the transgenes in the plant genome and their stable expression was demonstrated by fluorometric GUS assay, determination of NPTII activity and PCR analysis. This method allows the production of transgenic trees of P. elongata in a relatively short time.

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Las plantas, al ser organismos sésiles sufren diferentes tipos de estreses bióticos y abióticos. En este trabajo se cultivaron  in vitro plantas de orégano, bajo condiciones de estrés salino (NaCl 25 mM), en diferentes fuentes de luz: blanca (CTL), ultravioleta tipo C (UV-C) y de amplio espectro (AE). Se evaluaron cambios morfológicos en las plantas tratadas, así como parámetros fitoquímicos (fenoles y flavonoides totales y la capacidad antioxidante). Los tratamientos NaCl/CTL y AE mostraron el mayor número de yemas activadas. La luz UV-C mostró la menor cantidad de yemas y de altura de planta, sin embargo, no se observó efecto de la salinidad. La luz UV-C causó el menor número de hojas, así como raíces adventicias. No parece haber injerencia de la condición salinidad en estos resultados. La condición que provocó el mayor contenido de fenoles fue la luz UV-C y la que provocó el mayor contenido de flavonoides fue la combinación NaCl/UV-C. La combinación NaCl/AE causó la mayor capacidad antioxidante con el método DPPH y ABTS. No se observó una correlación entre el contenido de fenoles y la capacidad antioxidante.

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