Abstract

The role of competitive interactions among endophytes and latent pathogens that determine disease on stressed plants is largely unknown. Shoot blight caused byDiplodia sapineais an emerging disease affecting pine forests in Europe.D. sapineais an endophyte that becomes pathogenic following drought or hail. Disease expression depends on the availability of nutrient-rich metabolites produced by trees to alleviate stress. We studied whether competition for these compounds with other endophytes could modulate symptom expression. We compared the shoot-inhabiting fungal community of trees that developed blight symptoms or remained asymptomatic following a hailstorm that affected four pine species. Communities were characterised by isolation and metabarcoding of the ITS2 region. Endophytes were functionally annotated in their response to C, N and proline. Hail promotedD. sapineaand other endophytes with a rapid colonisation strategy of N-rich substrates. Asymptomatic trees had a community of endophytes showing a strong negative association withD. sapinea. These antagonistic endophytes were functionally similar toD. sapineain their response traits to hail, but they were more specialised to proline. The association was conserved across pine species. Our data suggest that after a stress-inducing event, rapid niche occupation is critical forD. sapineato cause disease. However, competition with other endophytes for key metabolites can supress the pathogen and prevent trees from developing symptoms. Our findings can pave the way to a better understanding of the contribution of latent pathogens on widespread tree mortality events involving abiotic stressors, such as drought, heat or hail. A freePlain Language Summarycan be found within the Supporting Information of this article.

Keywords

Diplodia sapinea; drought-induced mortality; endophytes; functional diversity; microbiome; proline

Published in

Functional Ecology
2020, Volume: 35, number: 1, pages: 239-254
Publisher: WILEY

SLU Authors

• Redondo, Miguel Angel

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Ecology


Publication identifier

DOI: https://doi.org/10.1111/1365-2435.13692

Permanent link to this page (URI)

https://res.slu.se/id/publ/108644