The serine protease inhibitors (SPIs) are widely distributed in living organisms like bacteria, fungi, plants, and humans. The main function of SPIs as protease enzymes is to regulate the proteolytic activity. In plants, most of the studies of SPIs have been focused on their physiological role. The initial studies carried out in plants showed that SPIs participate in the regulation of endogenous proteolytic processes, as the regulation of proteases in seeds. Besides, it was observed that SPIs also participate in the regulation of cell death during plant development and senescence. On the other hand, plant SPIs have an important role in plant defense against pests and phytopathogenic microorganisms. In the last 20 years, several transgenic plants over-expressing SPIs have been produced and tested in order to achieve the increase of the resistance against pathogenic insects. Finally, in molecular farming, SPIs have been employed to minimize the proteolysis of recombinant proteins expressed in plants. The present review discusses the potential biotechnological applications of plant SPIs in the agriculture field.

Título en ingles: Identification, in vitro establishment and preliminary phytochemical analysis of wild yam (Dioscorea spp.) used for medicinal purposes Título corto: Identificación, establecimiento in vitro y análisis fitoquímico preliminar de especies silvestres de ñame Resumen:  Tubérculos del género Dioscorea comercializados con fines medicinales, fueron recolectados con el propósito de lograr su establecimiento a condiciones in vitro. Previamente se lograron identificar taxonómicamente las especies y por medio de análisis fitoquímicos demostrar su potencial farmacéutico. El material recolectado fue identificado como Dioscorea coriacea, D. lehmannii, D. meridensis, D. polygonoides y una especie comestible D. trifida. Tubérculos recolectados de centros de acopio y traídos de campo fueron lavados, desinfectados, asperjados con Ácido Giberélico (AG₃) y sembrados en sustrato BM-2®, en invernadero a 18°C día y 10°C noche. Los tubérculos completos o por secciones fueron almacenados en bolsas herméticas a temperatura ambiente. Posteriormente se desinfectó material vegetal de las especies D. coriacea, D. lehmannii, D. meridensis y D polygonoides, seleccionando explantes de brotes sanos (D. coriacea / laboratorio) para su establecimiento. Se evaluaron tres medios de cultivo para establecimiento, el que presentó los mejores resultados fue Medio Murashige & Skoog (1962) suplementado con BAP 1 mL/L, AG₃ 1 mL/L y Putrescina 2 mL/L. Para la extracción y análisis de metabolitos secundarios se utilizaron tubérculos de D. coriacea, D. lehmannii y D. polygonoides, empleando como solvente de extracción metanol. Se encontró mayor concentración de extracto vegetal en D. coriacea (54%), y mediante cromatografía en capa delgada (CCD), se confirmó la presencia de saponinas, que resultó mayor en comparación con D. polygonoides especie reconocida por su alto contenido de saponinas. Estos resultados permitirán realizar análisis más avanzados de los compuestos presentes y plantear su propagación masiva en condiciones in vitro. Palabras clave: diosgenina, micropropagación, ñame silvestre, cultivo de tejidos vegetales, saponinas, fitoquímica. Abstract:  Wild tubers of the genus Dioscorea sold for medicinal use were collected for the purpose of achieving its establishment under in vitro conditions. First we taxonomically identified the species and through phytochemical analysis demonstrated pharmaceutical potential. The material collected was identified as Dioscorea coriacea, D. lehmannii, D. meridensis, D. polygonoides and the edible species D. trifida. Tubers collected from wholesale distributors and from the field were washed, disinfected, sprayed with Gibberellic Acid (GA₃) and planted in substrate BM-2®, in a greenhouse at 18 ° C during the day and 10 ° C overnight. Whole tubers or sections thereof were stored in sealed bags at room temperature. Subsequently plant material of the species D. coriacea, D. lehmannii, D. meridensis and D. polygonoides was disinfected and healthy buds (D. coriacea / laboratory) were selected for in vitro establishment. Three different culture media were evaluated for establishment; that which presented the best results was the Murashige & Skoog (1962) medium, supplemented with BAP 1 mL / L, GA₃ 1 mL / L and Putrescin 2 mL / L. For the collection and analysis of secondary metabolites, tubers of D. coriacea, D. lehmannii and D. polygonoides were used, using methanol as the extraction solvent. The highest concentration of plant extract, 54%, was found in D. coriacea, a higher value than that of D. polygonoides, which had been reported previously; the presence of saponins was confirmed by thin layer chromatography (TLC). These results will enable more advanced analysis of the present compounds and enhance their mass propagation under in vitro conditions. Key words: diosgenin, micropropagation, wild yam, tissue culture, saponins, phitochemistry. Recibido: agosto 20 de 2014      Aprobado: abril 20 de 2015