A glimmer of hope - ash genotypes with increased resistance to ash dieback pathogen show cross-resistance to emerald ash borer

Abstract

Plants rely on cross-resistance traits to defend against multiple, phylogenetically distinct enemies. These traits are often the result of long co-evolutionary histories. Biological invasions can force naive plants to cope with novel, coincident pests, and pathogens. For example, European ash (Fraxinus excelsior) is substantially threatened by the emerald ash borer (EAB), Agrilus planipennis, a wood-boring beetle, and the ash dieback (ADB) pathogen, Hymenoscyphus fraxineus. Yet, plant cross-resistance traits against novel enemies are poorly explored and it is unknown whether na_ive ash trees can defend against novel enemy complexes via cross-resistance mechanisms.To gain mechanistic insights, we quantified EAB performance on grafted replicates of ash genotypes varying in ADB resistance and characterized ash phloem chemistry with targeted and untargeted metabolomics.Emerald ash borer performed better on ADB-susceptible than on ADB-resistant genotypes. Moreover, changes in EAB performance aligned with differences in phloem chemical profiles between ADB-susceptible and ADB-resistant genotypes.We show that intraspecific variation in phloem chemistry in European ash can confer increased cross-resistance to invasive antagonists from different taxonomic kingdoms. Our study suggests that promotion of ADB-resistant ash genotypes may simultaneously help to control the ADB disease and reduce EAB-caused ash losses, which may be critical for the long-term stability of this keystone tree species.

Keywords

ash dieback; cross-resistance; defense chemistry; emerald ash borer; Fraxinus; intraspecific variation; invasive species; metabolomics

Published in

New Phytologist
2023, volume: 240, number: 3, pages: 1219-1232
Publisher: WILEY

SLU Authors

• Cleary, Michelle

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network
SLU Forest Damage Center

UKÄ Subject classification

Botany
Genetics and Breeding

Publication identifier

• DOI: https://doi.org/10.1111/nph.19068

Permanent link to this page (URI)

https://res.slu.se/id/publ/123044