Spanish ecological battleground: population structure of two invasive fungi, Cryphonectria parasitica and Fusarium circinatum

Farooq Ahmad; Julio Javier Diez

doi:10.3389/fpls.2023.1310254

Spanish ecological battleground: population structure of two invasive fungi, Cryphonectria parasitica and Fusarium circinatum

Front Plant Sci. 2023 Dec 21:14:1310254. doi: 10.3389/fpls.2023.1310254. eCollection 2023.

Authors

Farooq Ahmad^{1

2}, Julio Javier Diez^{1

2}

Affiliations

¹ Department of Plant Production and Forest Resources, University of Valladolid, Palencia, Spain.
² Sustainable Forest Management Research Institute, University of Valladolid and INIA, Palencia, Spain.

Abstract

Introduction: Invasive fungi distributed worldwide through globalization have caused devastating diseases in different forests, causing economic and ecologic disturbances. Two such invasive species are Cryphonectria parasitica and Fusarium circinatum, which were introduced to Europe from North America, separated temporally: C. parasitica was introduced about nine decades ago, whereas F. circinatum was introduced around two decades ago. As C. parasitica had a longer time to undergo genetic changes, we hypothesized that it has higher genetic diversity than the recently introduced F. circinatum in Spain. In addition, we studied the genetic characterization of both fungi present in similar ecological conditions in Northern Spain with the aim of providing data for biocontrol measures.

Methods: Molecular genetic markers were used to test these hypotheses, including mating type and DNA sequencing of internal transcribed spacer (ITS) regions. In addition, we used vegetative compatibility (VC) type markers in C. parasitica as the information about VC type is essential to apply biocontrol against the fungus.

Results and discussion: All the isolates of C. parasitica from the studied area belonged to only one VC type (EU-1) and one mating type (MAT-2). However, three distinct haplotypes of C. parasitica were identified through ITS sequencing, showing that multiple introductions might have happened to Cantabria. Among F. circinatum, no diversity was observed in ITS and MAT loci in the studied area but isolates from other Spanish regions showed the presence of both mating types. Overall, C. parasitica had higher genetic diversity than F. circinatum, despite both organisms appearing to reproduce clonally. This study helped understand the invasion patterns of C. parasitica and F. circinatum in northern Spain and will be useful in applying biocontrol measures against both pathogens.

Keywords: ITS sequence analysis; chestnut blight fungus; genetic diversity; invasive plant pathogens; mating type (MAT) alleles; pine pitch canker (PPC); population genetics; vegetative compatibility group (VCG).

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was funded by the regional government of Cantabria, Spain (Gobierno de Cantabria) under the project “Estudio de grupos de compatibilidad de Cryphonectria parasitica en sotos de castaño en Cantabria” (061/220832). Junta de Castilla y León (Spain) is also acknowledged for funding the postdoctoral fellowship of FA through the project Escalera de Excelencia “CLU-2019-01 - iuFOR Institute Unit of Excellence” of the University of Valladolid and co-financed by the European Regional Development Fund (ERDF “Europe drives our growth”). Other projects that supported the work were PID2019-110459RB-I00 and PLEC2021-008076 funded by MICINN (Spain) as well as the project VA208P20 funded by JCYL (Spain).