Isolation and characterization of two strains of Fusarium oxysporum causing potato dry rot in Solanum tuberosum in Colombia.

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Bibliographic Details
Title: Isolation and characterization of two strains of Fusarium oxysporum causing potato dry rot in Solanum tuberosum in Colombia.
Alternate Title: Aislamiento y caracterización de dos cepas de Fusarium oxysporum causantes de la pudrición seca en Solanum tuberosum en Colombia.
Authors: Bayona, Leonor García1, Grajales, Alejandro1, Cárdenas, Martha Emiliana1, Sierra, Roberto1, Lozano, Gabriel1, Garavito, Manuel Fernando1, De García, María Caridad Cepero1, Bernal, Adriana1, Jiménez, Pedro2, Restrepo, Silvia1 srestrep@uniandes.edu.co
Source: Revista Iberoamericana de Micologia. Dec2011, Vol. 28 Issue 4, p166-172. 7p.
Subjects: FUSARIUM oxysporum, SERPULA lacrymans, POTATOES, RIBOSOMES, POLYMERASE chain reaction, PLANT molecular biology
Geographic Terms: COLOMBIA
Abstract (English): Background: Fusarium oxysporum has worldwide distribution and causes severe vascular wilt or root rot in many plants. Strains are classified into formae speciales based on their high degree of host specificity, of which multilocus sequence typing provides a fairly good estimate. Aims: The main aim of this study was to identify the causal agent of an infected potato tuber in Colombia. Methods: Two F. oxysporum isolates were recovered from a potato tuber showing symptoms of dry rot. Both macroscopic and microscopic morphology differences were observed between the two isolates. Koch's postulates were verified and in quantitative tuber pathogenecity trials, both isolates induced moderate dry rot. Ribosomal internal transcribed spacer (ITS) and partial intergenic spacer region (IGS) sequences were PCR-amplified, sequenced and shown to be identical for the two isolates. A maximum parsimony phylogeny was created using F. oxysporum IGS sequences available in the Genebank database, which does not include sequences from the formae speciales tuberosi. Results: Our two isolates were most closely related to a red clover (Trifolium pratense) pathogenic isolate and two non-pathogenic F. oxysporum isolates from birdsfoot trefoil (Lotus corniculatus) and Lycopersicon sp. rhyzosphere (99% identity). Conclusions: These experiments showed that our isolates are not restricted to potato and that a molecular marker is needed to differentiate the formae speciales since the IGS and EF-1α do not have the power to do it. [ABSTRACT FROM AUTHOR]
Abstract (Spanish): Antecedentes: Fusarium oxysporum tiene distribución mundial y causa en varias plantas el marchitamiento vascular severo o la pudrición de la raíz. Las cepas se clasifican en formae speciales basándose en su alto grado de especificidad por un hospedero. Se puede obtener una muy buena estimación de ésta por medio de la tipificación con secuencia de múltiples locus. Objetivos: El objetivo principal de este estudio consistió en la identificación del agente causal de un tubérculo infectado en Colombia. Métodos: Dos aislados diferentes de F. oxysporum se recuperaron a partir de un tubérculo de papa que mostraba síntomas de pudrición seca. Se observaron diferencias tanto macroscópicascomomicroscópicas entre los aislamientos. Se verificaron los postulados de Koch y al llevar a cabo ensayos cuantitativos de patogenicidad, ambos aislamientos produjeron los síntomas de la pudrición seca. Se amplificaron por PCR y se secuenciaron regiones del espaciador interno transcrito (ITS) y el espaciador intergénico (IGS) ribosómico. Resultados: Las secuencias obtenidas fueron idénticas entre los dos aislamientos. Se reconstruyó una filogenia por máxima parsimonia con las secuencias de IGS disponibles en la base de datos de GenBank, que no incluye secuencias de la forma specialis tuberosi. Nuestros dos aislamientos mostraron estar más cercanamente relacionados con un aislamiento patogénico de trébol rojo (Trifolium pratense) y dos aislamientos no patogénicos de Lotus corniculatus y la rizósfera de Lycopersicon sp. (99% identidad). Conclusiones: Estos experimentos demuestran que los aislamientos obtenidos no solo son capaces de afectar a la patata y que se requiere un marcador molecular que permita delimitar las formas especiales ya que ni el IGS ni el EF-1α tienen el poder de resolución suficiente para hacerlo. [ABSTRACT FROM AUTHOR]
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Database: MedicLatina
Description
Abstract:Background: Fusarium oxysporum has worldwide distribution and causes severe vascular wilt or root rot in many plants. Strains are classified into formae speciales based on their high degree of host specificity, of which multilocus sequence typing provides a fairly good estimate. Aims: The main aim of this study was to identify the causal agent of an infected potato tuber in Colombia. Methods: Two F. oxysporum isolates were recovered from a potato tuber showing symptoms of dry rot. Both macroscopic and microscopic morphology differences were observed between the two isolates. Koch's postulates were verified and in quantitative tuber pathogenecity trials, both isolates induced moderate dry rot. Ribosomal internal transcribed spacer (ITS) and partial intergenic spacer region (IGS) sequences were PCR-amplified, sequenced and shown to be identical for the two isolates. A maximum parsimony phylogeny was created using F. oxysporum IGS sequences available in the Genebank database, which does not include sequences from the formae speciales tuberosi. Results: Our two isolates were most closely related to a red clover (Trifolium pratense) pathogenic isolate and two non-pathogenic F. oxysporum isolates from birdsfoot trefoil (Lotus corniculatus) and Lycopersicon sp. rhyzosphere (99% identity). Conclusions: These experiments showed that our isolates are not restricted to potato and that a molecular marker is needed to differentiate the formae speciales since the IGS and EF-1α do not have the power to do it. [ABSTRACT FROM AUTHOR]
ISSN:11301406
DOI:10.1016/j.riam.2011.03.007