Cell division events are essential for embryo patterning and morphogenesis: studies on dominant-negative cdc2aAt mutants of arabidopsis.

During plant development, cell division events are coordinately regulated, leading to specific growth patterns. Experimental evidence indicates that the morphogenetic controls that act at the vegetative plant growth stage are flexible and tolerate distortions in patterns and frequencies of cell division. To address questions concerning the relationship between cell division and embryo formation, a novel experimental approach was used. The frequencies of cell division were reduced exclusively during embryo development of Arabidopsis by the expression of a dominant cdc2a mutant. The five independent transgenic lines with the highest levels of the mutant cdc2a affected embryo formation. In the C13 line, seeds failed to germinate. The C1, C5 and C12 lines displayed a range of distortions on the apical-basal embryo pattern. In the C3 line, the shoot apical meristem of the seedlings produced leaves defective in growth and with an incorrect phyllotactic pattern. The results demonstrate that rates of cell division do not dictate cellular differentiation of embryos. Nevertheless, whereas cell divisions are uncoupled from vegetative development, they are instrumental in elaborating embryo structures and modulating embryo and seedling morphogenesis.

Transformación eficiente de Agrobacterium tumefaciens con ADN plásmídico por electroporación / High-efficiency transformation of agrobacterium tumefaciens with plasmid DNA by electroporation

Se describe un método simple y altamente eficiente para transformar directamente Agrobacterium tumefaciens con ADN plasmídico. El protocolo se basa en la electropermeabilización de la pared celular bajo la acción de un campo electrico de alto voltaje y se obtienen resultados reproducibles transformantes por microgramo de ADN plasmídico. Usualmente, la electroporación se realiza en una solución de polietilén-glicol al 15 % y una magnitud del campo eléctrico de 12.5 kV/cm. La utilidad de este método de transformación es demostrada mediante el establecimiento de una genoteca de Arabidopsis thaliana directamente en Agrobacterium tumefaciens. Nuestros resultados ofrecen interesantes perspectivas para la transferencia de bancos de genes y la complementación génica en plantas prescindiendo del uso de Escherichia coli como hospedero intermediario