Efecto de extracto de cáscara de quinua sobre el crecimiento y germinación de Botrytis cinerea y Penicillium italicum : evaluación del posible mecanismo de acción
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Fecha
2019
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es
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Universidad Andrés Bello
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Licencia CC
Licencia CC
Resumen
Los cítricos son los cultivos frutales más importantes a nivel mundial y constituyen una
excelente fuente de nutrientes y antioxidantes. La contaminación por hongos es un problema
asociado al cultivo de cítricos, lo que genera grandes pérdidas económicas.
En los cítricos, los hongos que tienen mayor incidencia son Penicillium italicum (causante
del moho azul) y Botrytis cinerea (causante del moho gris). Ambos tienen la capacidad de
ingresar al fruto mediante heridas en la superficie de la fruta o por secreción activa de
enzimas. Comúnmente, se utilizan fungicidas químicos sintéticos para controlar este tipo de
contaminación, lo que ha generado en la última década la aparición de cepas resistentes.
El estudio de metabolitos secundarios (MS), obtenidos desde plantas, se vislumbra como una
estrategia interesante de explorar para la generación de fungicidas naturales que suplan
algunas de las desventajas de los fungicidas sintéticos, tales como la generación de resistencia
en cepas de B. cinerea y P. italicum y presencia de residuos de estos en frutas en destino. Las
saponinas corresponden a metabolitos secundarios de implicadas en la resistencia al ataque
de patógenos, siendo abundantes en la cascarilla de quinua chilena (Chenopodium quinoa).
En esta tesis se realizó la extracción de saponinas desde la cascarilla de quinua contemplando
4 etapas principales: (I) maceración, (II) precipitación de proteínas, (III) hidrólisis alcalina y
(IV) ajuste de pH. Además, se evaluó el efecto de la temperatura (24 °C y 60 °C) en la etapa
I, y el efecto de ausencia o presencia de la etapa III. El extracto 1 fue sometido a
calentamiento (60°C) y a la etapa III, el extracto 2 fue sometido a calentamiento (60°C) en la
etapa I, y el extracto 3 se mantuvo a 24°C. Finalmente, se evaluó la actividad antifúngica de
tres extractos de quinua, enriquecidos en saponinas, sobre el crecimiento y germinación de
Penicillium italicum y Botrytis cinerea. Además se estudió el mecanismo de acción que
ejercen estos extractos contra el hongo.
Los resultados muestran que el extracto 1 presenta una mayor cantidad de saponinas (48,5%
peso seco) en comparación a los extractos 2 y 3. También, posee un efecto fungistático
relevante en los hongos estudiados, disminuyendo el crecimiento micelial de ambos hongos.
Además, los extractos 1, 2 y 3 producen una disminución en el porcentaje de germinación de
B. cinerea y P. italicum, pero el efecto de éste último es más notorio. Se encontró que el
extracto 1 aumenta la producción de ROS en P. italicum y causa daño en la membrana
plasmática de ambos hongos. Los resultados anteriores sugieren que el extracto 1 podría ser
utilizado en el desarrollo de algún fungistático.
Citrus fruits are the most important fruit crops worldwide and constitute an excellent source of nutrients and antioxidants. Fungal contamination is a problem associated with the cultivation of citrus fruits, which generates large economic losses. In citrus fruits, the fungi that have the highest incidence are Penicillium italicum (which causes blue mold) and Botrytis cinerea (which causes gray mold). Both fungi have the ability to enter the fruit through wounds on the fruit surface or by active secretion of enzymes. Commonly, synthetic chemical fungicides are used to control this type of contamination, which has resulted in the generation of resistant strains in the last decade. The study of secondary metabolites (MS), obtained from plants, is seen as an interesting strategy to explore for the generation of natural fungicides that overcome some of the disadvantages of synthetic fungicides, such as the generation of resistance in strains of B. cinerea and P. italicum, and the presence of these residues in fruits at destination. Saponins correspond to secondary metabolites involved in resistance to pathogen attack, being abundant in the Chilean quinoa husk (Chenopodium quinoa). In this thesis, saponins were extracted from the quinoa husk contemplating 4 main stages: (I) maceration, (II) protein precipitation, (III) alkaline hydrolysis and (IV) pH adjustment. In addition, the effect of temperature (24 ° C and 60 ° C) in stage I was evaluated, and the effect of absence or presence of stage III. Extract 1 was subjected to heating (60 ° C) and to stage III, extract 2 was subjected to heating (60 ° C) in stage I, and extract 3 was maintained at 24 °C. Finally, the antifungal activity of three quinoa extracts, enriched in saponins, on the growth and germination of Penicillium italicum and Botrytis cinerea was evaluated. In addition, the mechanisms of action exerted by these extracts against the fungus were studied. The results show that extract 1 has a greater amount of saponins (48.5% dry weight) compared to extracts 2 and 3. It also has a relevant fungistatic effect on the fungi studied, reducing the mycelial growth of both fungi. Additionally, extracts 1, 2 and 3 produce a decrease in the germination percentage of B. cinerea and P. italicum, but the effect of the latter is more noticeable. In P. italicum, it was found that extract 1 increases the production of ROS, and the same extract causes damage to the plasma membrane of both fungi. The previous results suggest that extract 1 could be used in the development of some fungistatic.
Citrus fruits are the most important fruit crops worldwide and constitute an excellent source of nutrients and antioxidants. Fungal contamination is a problem associated with the cultivation of citrus fruits, which generates large economic losses. In citrus fruits, the fungi that have the highest incidence are Penicillium italicum (which causes blue mold) and Botrytis cinerea (which causes gray mold). Both fungi have the ability to enter the fruit through wounds on the fruit surface or by active secretion of enzymes. Commonly, synthetic chemical fungicides are used to control this type of contamination, which has resulted in the generation of resistant strains in the last decade. The study of secondary metabolites (MS), obtained from plants, is seen as an interesting strategy to explore for the generation of natural fungicides that overcome some of the disadvantages of synthetic fungicides, such as the generation of resistance in strains of B. cinerea and P. italicum, and the presence of these residues in fruits at destination. Saponins correspond to secondary metabolites involved in resistance to pathogen attack, being abundant in the Chilean quinoa husk (Chenopodium quinoa). In this thesis, saponins were extracted from the quinoa husk contemplating 4 main stages: (I) maceration, (II) protein precipitation, (III) alkaline hydrolysis and (IV) pH adjustment. In addition, the effect of temperature (24 ° C and 60 ° C) in stage I was evaluated, and the effect of absence or presence of stage III. Extract 1 was subjected to heating (60 ° C) and to stage III, extract 2 was subjected to heating (60 ° C) in stage I, and extract 3 was maintained at 24 °C. Finally, the antifungal activity of three quinoa extracts, enriched in saponins, on the growth and germination of Penicillium italicum and Botrytis cinerea was evaluated. In addition, the mechanisms of action exerted by these extracts against the fungus were studied. The results show that extract 1 has a greater amount of saponins (48.5% dry weight) compared to extracts 2 and 3. It also has a relevant fungistatic effect on the fungi studied, reducing the mycelial growth of both fungi. Additionally, extracts 1, 2 and 3 produce a decrease in the germination percentage of B. cinerea and P. italicum, but the effect of the latter is more noticeable. In P. italicum, it was found that extract 1 increases the production of ROS, and the same extract causes damage to the plasma membrane of both fungi. The previous results suggest that extract 1 could be used in the development of some fungistatic.
Notas
Tesis (Magíster en Biotecnología)
Palabras clave
Cítricos, Enfermedades por Hongos, Control Biológico, Fungicidas, Quinoa, Investigaciones, Hongos Fitopatógenos