Etilogía del cancér del tallo provocado por Neoscytalidium dimidiatum (Penz) EN Hylocereus costaricensis, en Costa Rica
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Fecha
2019
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artículo original
Autores
Retana Sánchez, Kenneth
Castro Zúñiga, Oscar
Blanco Meneses, Mónica
Quesada González, Andrea
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En el 2011 y 2012 se realizó una investigación de los agentes causales de las enfermedades asociadas al cultivo de Pitaya (Hylocereus costaricensis) en Costa Rica. Una de las más importantes durante el periodo de estudio, debido a su alta incidencia (100%), fue el cáncer en el tallo. Los síntomas observados fueron pequeñas manchas anaranjadas y rojizas irregulares y lesiones de coloración beige-grisáceas con el centro abultado. Para determinar el agente causal se recolectaron 85 muestras, cladodios completos con diferentes estados de desarrollo de la enfermedad, a partir de los cuales se realizaron 40 aislamientos. De estos creció un organismo en forma consistente, con el cual se llevó a cabo
la identificación, caracterización morfológica y molecular así como la verificación de los postulados de Koch. De acuerdo con la forma de crecimiento, coloración del micelio y la morfología de los artroconidios y de las características moleculares (secuenciación de la región ITS), el patógeno asociado a los síntomas presentó un 99% de similitud con Neoscytalidium dimidiatum (Penz.) (no. de accesión KJ513460, del hongo aislado en Costa Rica). En las pruebas de los postulados de Koch se obtuvo un 92% de infección y se presentó una sintomatología similar a la observada en el campo, además, se recuperó el mismo organismo que fue inoculado. Este es el primer reporte de este hongo causando daños en el tallo de Hylocereus costaricensis en Costa Rica.
In 2011 infected samples were examined to identify the causal agent of stem rot of Hylocereus costaricensis in Costa Rica. During the rainy season, symptoms associated with the disease included a small yellowish rot that typically started from the edge of the cladodium and extended inward towards the stem. Eventually the whole stem decayed. During the dry season, orange circular spots appeared on the stem, turning dark brown. For determine the causal agent, were collected 25 samples of each type of decay, complete cladodes with different stages of symptom development, from which 15 isolations of each disease were made. A bacterium was obtained consistently from each symptomatology, ith which the identification, characterization based on biochemical tests and molecular identification was carried out, as well as the verification of Koch’s postulates. Results indicated that the symptoms were caused by the same bacteria. Based on sequencing of the 16S region, the bacterium showed 99.2% similarity with Enterobacter hormaechei (KJ999997). According to Koch’s postulates, a similar symptomatology was obtained on plants from the field and on inoculated plants. This is the first report of this pathogen causing damage to the stem of Hylocereus costarricensis in American continent.
In 2011 infected samples were examined to identify the causal agent of stem rot of Hylocereus costaricensis in Costa Rica. During the rainy season, symptoms associated with the disease included a small yellowish rot that typically started from the edge of the cladodium and extended inward towards the stem. Eventually the whole stem decayed. During the dry season, orange circular spots appeared on the stem, turning dark brown. For determine the causal agent, were collected 25 samples of each type of decay, complete cladodes with different stages of symptom development, from which 15 isolations of each disease were made. A bacterium was obtained consistently from each symptomatology, ith which the identification, characterization based on biochemical tests and molecular identification was carried out, as well as the verification of Koch’s postulates. Results indicated that the symptoms were caused by the same bacteria. Based on sequencing of the 16S region, the bacterium showed 99.2% similarity with Enterobacter hormaechei (KJ999997). According to Koch’s postulates, a similar symptomatology was obtained on plants from the field and on inoculated plants. This is the first report of this pathogen causing damage to the stem of Hylocereus costarricensis in American continent.
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Pudrición marrón, Hylocereus costaricensis, Enterobacter hormaechei, Brown rot, Hylocereus costaricensis, Enterobacter hormaechei