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Sensibilidad de 𝘊𝘰𝘭𝘭𝘦𝘵𝘰𝘵𝘳𝘪𝘤𝘩𝘶𝘮 𝘴𝘱𝘱. a inhibidores de quinona
Soto Alonso, Kiara S.
Soto Alonso, Kiara S.
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Abstract
El tubérculo de mayor producción y consumo en Puerto Rico es el ñame (Dioscorea spp.). Este cultivo se ve afectado por enfermedades como la “candelilla” causada por Colletotrichum spp. El control de esta enfermedad en la isla se basa principalmente en la utilización de fungicidas inhibidores de quinona (QoI). Sin embargo, en la última década se ha observado una reducción en la eficacia de los mismos a nivel de campo, en adición al hallazgo de nuevas especies de Colletotrichum spp. afectando al cultivo. Los objetivos de esta investigación fueron evaluar la sensibilidad de aislados de Colletotrichum, previamente expuestos a fungicidas QoI. La evaluación se realizó utilizando ensayos colorimétricos, medios enmendados y germinación de conidios a concentraciones de 0.0, 0.01, 0.10, 1.0, 5.0, y 10.0 µg/mL con y sin ácido salicilhidroxámico (SHAM). Se obtuvieron 17 aislados de Colletotrichum. Se seleccionaron tres basados en su patogenicidad, estos fueron caracterizados morfológica, patogénica y molecularmente (ITS, ACT, GAPDH, CAL, TUB2 y SOD2). Se identificó un aislado de Colletotrichum siamense en D. alata cv. Diamantes y dos aislados de Colletotrichum queenslandicum en D. rotundata cv. Guinea Negro. Siendo este último el primer reporte de esta especie afectando este cultivar en Puerto Rico. En todos los ensayos realizados, los dos aislados de Colletotrichum queenslandicum presentaron mayor sensibilidad a Az que el aislado de Colletotrichum siamense. A nivel curativo (medios enmendados) ninguno de los aislados presentó niveles de inhibición igual o mayor al 50 %, evidenciando la pérdida de sensibilidad a nivel micelial. Sin embargo, a nivel preventivo (germinación de conidios) solo C. siamense presentó una reducción en la sensibilidad con porcentajes de inhibición de 0 % en las concentraciones más bajas a 25 % en las más altas. Es necesario la evaluación a nivel molecular de las regiones del citocromo b para la detección de mutaciones que puedan estar asociadas a la pérdida de sensibilidad en estos aislados. Además, se recomienda la implementación de prácticas de manejo para el desarrollo de resistencia a nivel de campo cuando se estén utilizando fungicidas a base de QoI.
The tuber with the highest production and consumption in Puerto Rico is the yam (Dioscorea spp.). This crop is affected by diseases such as "candelilla" caused by Colletotrichum spp. The control of this disease on the island is based mainly on using quinone inhibitor fungicides (QoI). However, in the last decade, there has been a reduction in its efficacy at field level and the discovery of new species of Colletotrichum spp. affecting the crop. This research aimed to evaluate the sensitivity of Colletotrichum isolates previously exposed to QoI fungicides. An evaluation was performed using colorimetric assays, amended media, and conidia germination at concentrations of 0.0, 0.01, 0.10, 1.0, 5.0, and 10.0 µg/mL with and without salicylhydroxamic acid (SHAM). Eighteen Colletotrichum isolates were obtained and based on their pathogenicity, three were selected that were characterized morphologically, pathogenically, and molecularly (ITS, ACT, GAPDH, CAL, TUB2, and SOD2). An isolate of Colletotrichum siamense was identified in D. alata cv. Diamantes and two isolates of Colletotrichum queenslandicum in D. rotundata cv. Black Guinea. The latter is the first report of this species affecting this cultivar in Puerto Rico. In all experiments, the two isolates of Colletotrichum queenslandicum showed greater sensitivity to Az than the Colletotrichum siamense isolate. At curative level (amended media assay), none of the isolates presented inhibition levels equal to or greater than 50 %, evidencing the loss of sensitivity at the mycelial level. However, at a preventive level (germination of conidia), only C. siamense presented a reduction in sensitivity with percentages of inhibition from 0 % at lower concentrations to 25 % at higher concentrations. Evaluation at the molecular level of the cytochrome b regions is necessary to detect mutations associated with loss of sensitivity in these isolates. In addition, implementing management practices for developing resistance at the field level is recommended when using QoI-based fungicides.
The tuber with the highest production and consumption in Puerto Rico is the yam (Dioscorea spp.). This crop is affected by diseases such as "candelilla" caused by Colletotrichum spp. The control of this disease on the island is based mainly on using quinone inhibitor fungicides (QoI). However, in the last decade, there has been a reduction in its efficacy at field level and the discovery of new species of Colletotrichum spp. affecting the crop. This research aimed to evaluate the sensitivity of Colletotrichum isolates previously exposed to QoI fungicides. An evaluation was performed using colorimetric assays, amended media, and conidia germination at concentrations of 0.0, 0.01, 0.10, 1.0, 5.0, and 10.0 µg/mL with and without salicylhydroxamic acid (SHAM). Eighteen Colletotrichum isolates were obtained and based on their pathogenicity, three were selected that were characterized morphologically, pathogenically, and molecularly (ITS, ACT, GAPDH, CAL, TUB2, and SOD2). An isolate of Colletotrichum siamense was identified in D. alata cv. Diamantes and two isolates of Colletotrichum queenslandicum in D. rotundata cv. Black Guinea. The latter is the first report of this species affecting this cultivar in Puerto Rico. In all experiments, the two isolates of Colletotrichum queenslandicum showed greater sensitivity to Az than the Colletotrichum siamense isolate. At curative level (amended media assay), none of the isolates presented inhibition levels equal to or greater than 50 %, evidencing the loss of sensitivity at the mycelial level. However, at a preventive level (germination of conidia), only C. siamense presented a reduction in sensitivity with percentages of inhibition from 0 % at lower concentrations to 25 % at higher concentrations. Evaluation at the molecular level of the cytochrome b regions is necessary to detect mutations associated with loss of sensitivity in these isolates. In addition, implementing management practices for developing resistance at the field level is recommended when using QoI-based fungicides.
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2023-05-01
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Colletotrichum, Yam, QoI Fungicides