Diversidad taxonómica y funcional del microbioma de la rizósfera y endófito de la filósfera de individuos de Araucaria araucana afectados por daño foliar en la Cordillera de Nahuelbuta.
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Date
2026
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
La muerte de copa de Araucaria araucana (Mol.) K. Koch constituye un problema sanitario y de conservación en la Cordillera de Nahuelbuta. Esta tesis caracterizó los hongos y oomicetos asociados a la rizósfera y al compartimento endofítico de las acículas. En la rizósfera se evaluaron la diversidad taxonómica y los grupos funcionales inferidos de las comunidades fúngicas en sitios contrastantes en condiciones edáficas y severidad de los síntomas de muerte de copa. Se comparó la detección de Phytophthora cinnamomi mediante cultivo, PCR específica y metabarcoding. En las acículas se optimizó la obtención de ADN y se caracterizaron las comunidades fúngicas endofíticas. Se aislaron hongos y oomicetos desde ambos ambientes y se evaluó el potencial patogénico de aislados seleccionados mediante inoculación de plantas. La muerte de copa no se asoció consistentemente con una disminución de la diversidad fúngica. En la rizósfera, las principales diferencias se observaron entre sitios y se relacionaron con sus condiciones edáficas. En las acículas no se detectaron diferencias significativas en la diversidad, composición ni grupos funcionales inferidos entre árboles asintomáticos y sintomáticos. Phytophthora cinnamomi fue confirmada en la rizósfera de ambas condiciones sanitarias, por lo que su presencia no explicó por sí sola la severidad de los síntomas. Los aislados seleccionados colonizaron las raíces de las plantas, pero ninguno aumentó significativamente la severidad de los síntomas de muerte de copa respecto del control no inoculado. Estos resultados constituyen una línea base para investigaciones y para la vigilancia fitosanitaria de los bosques de A. araucana.
Crown dieback of Araucaria araucana (Mol.) K. Koch is a plant health and conservation concern in the Nahuelbuta Range. This thesis characterized the fungi and oomycetes associated with the rhizosphere and the endophytic compartment of the needles. In the rhizosphere, the taxonomic diversity and inferred functional groups of fungal communities were evaluated at sites contrasting in soil conditions and crown dieback symptom severity. The detection of Phytophthora cinnamomi using culture-based methods, species-specific PCR, and metabarcoding was compared. In the needles, DNA recovery was optimized and endophytic fungal communities were characterized. Fungi and oomycetes were isolated from both environments, and the pathogenic potential of selected isolates was evaluated through plant inoculation assays. Crown dieback was not consistently associated with reduced fungal diversity. In the rhizosphere, the main differences were observed between sites and were related to their soil conditions. In the needles, no significant differences in diversity, composition, or inferred functional groups were detected between asymptomatic and symptomatic trees. Phytophthora cinnamomi was confirmed in the rhizosphere of trees under both health conditions; therefore, its presence alone did not explain symptom severity. The selected isolates colonized plant roots, but none significantly increased the severity of crown dieback symptoms relative to the non-inoculated control. These results provide a baseline for research and the phytosanitary surveillance of A. araucana forests.
Crown dieback of Araucaria araucana (Mol.) K. Koch is a plant health and conservation concern in the Nahuelbuta Range. This thesis characterized the fungi and oomycetes associated with the rhizosphere and the endophytic compartment of the needles. In the rhizosphere, the taxonomic diversity and inferred functional groups of fungal communities were evaluated at sites contrasting in soil conditions and crown dieback symptom severity. The detection of Phytophthora cinnamomi using culture-based methods, species-specific PCR, and metabarcoding was compared. In the needles, DNA recovery was optimized and endophytic fungal communities were characterized. Fungi and oomycetes were isolated from both environments, and the pathogenic potential of selected isolates was evaluated through plant inoculation assays. Crown dieback was not consistently associated with reduced fungal diversity. In the rhizosphere, the main differences were observed between sites and were related to their soil conditions. In the needles, no significant differences in diversity, composition, or inferred functional groups were detected between asymptomatic and symptomatic trees. Phytophthora cinnamomi was confirmed in the rhizosphere of trees under both health conditions; therefore, its presence alone did not explain symptom severity. The selected isolates colonized plant roots, but none significantly increased the severity of crown dieback symptoms relative to the non-inoculated control. These results provide a baseline for research and the phytosanitary surveillance of A. araucana forests.
Description
Tesis presentada para optar al grado de Doctor/a en Ciencias Forestales.
Keywords
Araucaria, Hongos, Oomycetes, Phytophthora cinnamomi