Estudio de la comunidad fúngica endofítica foliar de Araucaria araucana y sus posibles aplicaciones biotecnológica.
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Date
2025
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Universidad de Concepción
Abstract
Araucaria araucana es una especie arbórea emblemática de Chile y Argentina, con gran importancia cultural para las comunidades mapuches. Actualmente, amenazas como el cambio climático, la deforestación y la expansión humana han provocado una disminución significativa de sus poblaciones naturales. Entre los organismos que interactúan con esta especie, los hongos endófitos (HE) destacan por colonizar sus tejidos sin causar daño, favoreciendo su crecimiento y su defensa frente a patógenos. El objetivo de este estudio fue caracterizar la diversidad de hongos endófitos foliares presentes en A. araucana y evaluar su capacidad antagónica frente a hongos fitopatógenos, con miras a su eventual uso como agentes de biocontrol. Para ello, se realizó el aislamiento, purificación e identificación molecular de cepas obtenidas de tejido foliar sano en dos sitios de muestreo (Parque Nacional Villarrica y Reserva Malalcahuello), junto con ensayos de confrontación dual para determinar su eficacia biocontroladora. Se aislaron 203 cepas, identificándose 29 morfoespecies, de las cuales 16 fueron secuenciadas mediante análisis molecular. No presentaron diferencias significativas en cuanto a la diversidad de especies en ambos sitios. A pesar de que las muestras provenían de hojas sin síntomas visibles, se detectaron especies fúngicas patógenas, como Pewenomyces kalosus (cancro del pehuén), lo que sugiere posibles interacciones con endófitos capaces de limitar la infección en la planta. En los ensayos de confrontación dual se evaluó el potencial antagónico de cinco HE: Alternaria alternata (cepa 1), Pholiota sp. (cepa 3), Sydowia polyspora (cepa 7), Pseudocamarosporium brabeii (cepa 12) y Cladosporium ramotenellum (cepa 19) frente a Botrytis sp., Fusarium sp. y Phytophthora sp. Se registraron diferencias en los porcentajes de inhibición del crecimiento radial (PICR), destacando Pseudocamarosporium brabeii (cepa 12) con un 34,2% de inhibición del crecimiento de Botrytis sp., seguido de A. alternata (cepa 1) por su elevada capacidad inhibitoria: 19.6% frente a Botrytis sp. y 18.02% frente a Phytophthora sp. Estos resultados respaldan el potencial biotecnológico de los hongos endófitos foliares de A. araucana como agentes de biocontrol, contribuyendo a estrategias sostenibles para su conservación y la protección fitosanitaria.
Araucaria araucana is an emblematic tree species of Chile and Argentina, with great cultural significance for the Mapuche communities. Currently, threats such as climate change, deforestation, and human expansion have led to a significant decline in its natural populations. Among the organisms interacting with this species, endophytic fungi (EF) stand out for colonizing its tissues without causing damage, enhancing both its growth and defense against pathogens. The aim of this study was to characterize the diversity of foliar endophytic fungi associated with A. araucana and to assess their antagonistic capacity against phytopathogenic fungi, with a view toward their potential use as biocontrol agents. For this purpose, isolation, purification, and molecular identification of strains obtained from healthy foliar tissue in two sampling sites (Villarrica National Park and Malalcahuello Reserve) were performed, along with dual confrontation assays to determine their biocontrol efficacy. A total of 203 strains were isolated, identifying 29 morphospecies, of which 16 were sequenced through molecular analysis. No significant differences in species diversity were observed between the two sites. Although samples were obtained from asymptomatic leaves, pathogenic fungal species such as Pewenomyces kalosus (pehuén canker) were detected, suggesting possible interactions with endophytes capable of limiting infection in the plant. Dual confrontation assays were conducted to evaluate the antagonistic potential of five EF: Alternaria alternata (strain 1), Pholiota sp. (strain 3), Sydowia polyspora (strain 7), Pseudocamarosporium brabeii (strain 12), and Cladosporium ramotenellum (strain 19) against Botrytis sp., Fusarium sp., and Phytophthora sp. Differences in percentage inhibition of radial growth (PIRG) were recorded, with Pseudocamarosporium brabeii (strain 12) showing the highest inhibition of Botrytis sp. (34.2%), followed by A. alternata (strain 1), which exhibited high inhibitory capacity: 19.6% against Botrytis sp. and 18.02% against Phytophthora sp. These results support the biotechnological potential of foliar endophytic fungi from A. araucana as biocontrol agents, contributing to sustainable strategies for its conservation and phytosanitary protection.
Araucaria araucana is an emblematic tree species of Chile and Argentina, with great cultural significance for the Mapuche communities. Currently, threats such as climate change, deforestation, and human expansion have led to a significant decline in its natural populations. Among the organisms interacting with this species, endophytic fungi (EF) stand out for colonizing its tissues without causing damage, enhancing both its growth and defense against pathogens. The aim of this study was to characterize the diversity of foliar endophytic fungi associated with A. araucana and to assess their antagonistic capacity against phytopathogenic fungi, with a view toward their potential use as biocontrol agents. For this purpose, isolation, purification, and molecular identification of strains obtained from healthy foliar tissue in two sampling sites (Villarrica National Park and Malalcahuello Reserve) were performed, along with dual confrontation assays to determine their biocontrol efficacy. A total of 203 strains were isolated, identifying 29 morphospecies, of which 16 were sequenced through molecular analysis. No significant differences in species diversity were observed between the two sites. Although samples were obtained from asymptomatic leaves, pathogenic fungal species such as Pewenomyces kalosus (pehuén canker) were detected, suggesting possible interactions with endophytes capable of limiting infection in the plant. Dual confrontation assays were conducted to evaluate the antagonistic potential of five EF: Alternaria alternata (strain 1), Pholiota sp. (strain 3), Sydowia polyspora (strain 7), Pseudocamarosporium brabeii (strain 12), and Cladosporium ramotenellum (strain 19) against Botrytis sp., Fusarium sp., and Phytophthora sp. Differences in percentage inhibition of radial growth (PIRG) were recorded, with Pseudocamarosporium brabeii (strain 12) showing the highest inhibition of Botrytis sp. (34.2%), followed by A. alternata (strain 1), which exhibited high inhibitory capacity: 19.6% against Botrytis sp. and 18.02% against Phytophthora sp. These results support the biotechnological potential of foliar endophytic fungi from A. araucana as biocontrol agents, contributing to sustainable strategies for its conservation and phytosanitary protection.
Description
Tesis presentada para optar al título de Ingeniero en Biotecnología Vegetal