Spatial and temporal dynamics of the colonization of Pinus radiata by Fusarium circinatum, of conidiophora development in the pith and of traumatic resin duct formation

Authors

  • Noemí Martín-Rodrigues,

    Corresponding author
    • Laboratory of Plant Physiology, Department of Plant Biology and Ecology, University of the Basque Country UPV/EHU, Leioa, Vizcaya, Spain
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  • Santiago Espinel,

    1. Departament of Plant Production and Protection, Neiker-Tecnalia, Granja Modelo de Arkaute, Vitoria, Alava, Spain
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  • Joseba Sanchez-Zabala,

    1. Laboratory of Plant Physiology, Department of Plant Biology and Ecology, University of the Basque Country UPV/EHU, Leioa, Vizcaya, Spain
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  • Amaia Ortíz,

    1. Departament of Plant Production and Protection, Neiker-Tecnalia, Granja Modelo de Arkaute, Vitoria, Alava, Spain
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  • Carmen González-Murua,

    1. Laboratory of Plant Physiology, Department of Plant Biology and Ecology, University of the Basque Country UPV/EHU, Leioa, Vizcaya, Spain
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  • Miren K. Duñabeitia

    1. Laboratory of Plant Physiology, Department of Plant Biology and Ecology, University of the Basque Country UPV/EHU, Leioa, Vizcaya, Spain
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Author for correspondence:

Noemí Martín Rodrigues

Tel: +34 946015547

Email: noemi.martin@ehu.es

Summary

  • Fusarium circinatum causes pitch canker disease in a wide range of pine trees, including Pinus radiata, with devastating economic consequences.
  • To assess the spatial and temporal dynamics of growth of this pathogen in radiata pine, we examined the process of infection using both real-time PCR to quantify fungal biomass inside the plant host, and confocal microscopy using a green fluorescent protein (GFP)-tagged strain of F. circinatum.
  • Pathogen growth exhibited three distinct phases: an initial exponential increase in fungal biomass, concomitant with pathogen colonization of the cortex and phloem; a slowdown in fungal growth coincident with sporulating hyphae deep within the host; and stabilization of the fungal biomass when the first wilting symptoms appeared. The number of resin ducts in the xylem was found to increase in response to infection and the fungus grew inside both constitutive and traumatic resin ducts.
  • These results indicate that conidiation may contribute to the spatial or temporal dissemination of the pathogen. Moreover, the present findings raise the intriguing possibility that the generation of traumatic resin ducts may be of more benefit to the fungus than to the plant.

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