Browsing by Author "Sanfuentes, Eugenio"

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    Biocontrol of Sirex noctilio by the parasitic nematode Deladenus siricidicola : a five season field study in southern Chile
    (2018) Castillo, Miguel; Sanfuentes, Eugenio; Angulo, Andrés; Becerra, José; Romero Romero, Jesús L.; Arce Johnson, Jorge Patricio
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    Detection of Phytophthora cinnamomi on declining Araucaria araucana forests
    (2022) Sanfuentes, Eugenio; Gonzalez, Mariela; Castillo, Miguel; Rubilar, Rafael; Besoain, Ximena; Sanhueza, Claudia; Smith, Milena
    Since 2016, crown death and mortality of Araucaria araucana trees have been observed at different localities of the Nahuelbuta Coastal Range, Chile. The objective of this study was to determine the presence of Phytophthora spp. in the rhizosphere of A. araucana trees that may explain its decline. Samples of soil rhizosphere were collected from trees with crown death as well as from asymptomatic trees at two visually contrasting severity areas. Phytophthora detection from soil samples was carried out using leaf bait technique, and isolates were identified by morphology and molecular methods. Recovered Phytophthora isolates were used in pathogenicity tests with A. araucana plants. From rhizosphere soil samples of 30 A. araucana trees, 56 isolates of Phytophthora cinnamomi were obtained. Isolations were more frequent in the rhizosphere of trees with severe crown symptoms and originated exclusively from the selected area showing severe crown symptoms. Plant stem inoculation with P. cinnamomi isolates caused 100% mortality; however, through root infestation, mortality was variable depending on the specific isolate. These results are the first report of the pathogenicity of P.cinnamomi A2 in natural forests of A. araucana in Chile.
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    Relative Expression of Genes Elicited by Clonostachys rosea in Pinus radiata Induces Systemic Resistance
    (2024) Moraga-Suazo, Priscila; Le-Feuvre, Regis; Navarrete, Dario; Sanfuentes, Eugenio
    Radiata pine is one of the most commonly planted tree species in Chile due to its fast growth and desirable wood and pulp properties. However, its productivity is hampered by several diseases. Pitch canker disease (PCC) caused by Fusarium circinatum, is considered the most damaging disease to the pine forest industry. Several control measures have been established, with biological control emerging as an environmentally friendly and effective way for F. circinatum control. Previous studies support the value of Clonostachys rosea in reducing PCC damage, with evidence suggesting a potential induced systemic resistance (ISR) triggered in radiata pines by this agent. Ten-month-old radiata pine plants were pre-treated with C. rosea on a substrate at 8 and 1 days before inoculation with F. circinatum on the stem tip, and expression levels were determined for DXS1, LOX, PAL, and PR3 genes 24 h later. Lesion length was 45% lower on plants pre-treated with C. rosea and infected with F. circinatum compared to non-pre-treated and infected plants. Additionally, LOX and PR3 were induced 23 and 62 times more, respectively, in comparison to untreated plants. Our results indicate that C. rosea causes an ISR response in pre-treated plants, significantly increasing the expression of resistance genes and reducing lesion length.