Propagación clonal y almacenamiento criogénico de la planta medicinal Stevia rebaudiana

Successful clonal propagation of Stevia rebaudiana was achieved using microshoots as a primary step for in vitro conservation. Maximum proliferation was obtained on Murashige and Skoog (MS) medium supplemented with 1.5 mg L–1 benzyl amino purine and 0.2 mg L–1 indole-3-butyric-acid (IBA). Auxin increased rooting percentage of shoots at concentration of 0.4 mg L–1 IBA, indole-3-acetic-acid or naphthalene acetic acid and no rooting occurred without plant growth regulator. A survival of 90% was achieved when rooted explants were acclimatized in vivo in 1 soil: 1 perlite: 1 peat. In vitro S. rebaudiana shoots were successfully stored for up to 32 weeks on MS medium supplemented with an appropriate concentration of sucrose, sorbitol or mannitol, at 24 ± 2°C. After 32 weeks, 93.6% of the shoots were able to survive. Moreover, 89.3% of them were able to regrow when stored under light conditions. Cryopreservation by vitrification was successfully achieved (65.6% regrowth) when shoot tips were precultured on a medium supplemented with 0.4 M sorbitol for 2 d, followed by loading shoot tips with 80% concentrated plant vitrification solution 2 (PVS2) for 20 min; then dehydrated with 100% PVS2 for 60 min at 0°C prior to storage in liquid nitrogen. This procedure is easy to handle and produced a high levels of shoot formation. This protocol could be useful for longterm storage of S. rebaudiana germplasm.Se logró con éxito la propagación clonal de Stevia rebaudiana, utilizando microtallos como primer paso para su conservación in vitro. Se obtuvo la proliferación máxima en el medio Murashige y Skoog (MS) suplementado con 1,5 mg L–1 de bencil amino purina y 0,2 mg L–1 de ácido indol-3-butírico (IBA). Las auxinas aumentaron el porcentaje de enraizamiento de los brotes en la concentración de 0,4 mg L–1 de IBA, ácido indol-3-acético o el ácido naftalen acético, pero no se produjo enraizamiento sin regulador del crecimiento vegetal. Se logró una supervivencia del 90% cuando los explantes enraizados fueron aclimatizados in vivo en 1 suelo: 1 perlita: 1 turba. Se almacenaron con éxito brotes de S. rebaudiana in vitro hasta 32 semanas a 24 ± 2°C, en medio MS suplementado con una concentración apropiada de sacarosa, sorbitol o manitol. Después de 32 semanas, el 93,6% de los brotes fueron capaces de sobrevivir y el 89,3% fueron capaces de rebrotar cuando se almacenaron bajo condiciones de luz. Se logró con éxito (65,6% rebrotes) la criopreservación por vitrificación cuando los ápices se pre-cultivaron durante 2 días en un medio suplementado con sorbitol 0,4 M, y a continuación con una solución de vitrificación de la planta 2 (PVS2) al 80% durante 20 minutos, seguido de una deshidratación con PVS2 al 100% durante 60 min a 0°C antes de su almacenamiento en nitrógeno líquido. Este procedimiento es fácil de ejecutar y puede ser útil para el almacenamiento a largo plazo del germoplasma de S. rebaudiana

Sweet Peppers

Sweet pepper is an important greenhouse vegetable crop and highly attractive to multiple pest and pathogen species. The main pests and diseases detrimental to pepper crops in various parts of the globe are reported here, along with the most effective or sustainable control strategies currently applied to manage them. Biological control of the main pest species, such as thrips, whiteflies and spider mites, is in general very successful with generalist predators, because of their ability to establish populations prior to pest invasions by using the plant-provided pollen as an alternative food source. However, other pest species, such as aphids, stink bugs and the pepper weevil, are still hard to control without pesticides and require new tools for management that do not disrupt the robust system of biological control. Most diseases can be controlled well by managing the climate, soil solarization, growing out of soil or by applying bacterial or fungal antagonists. All these tools together offer the opportunity to manage most pest and diseases with a minimal use of pesticides