Abstract

Predicting whether naive tree populations have the potential to adapt to exotic pathogens is necessary owing to the increasing rate of invasions. Adaptation may occur as a result of natural selection when heritable variation in terms of susceptibility exists in the naive population. We searched for signs of selection on black alder (Alnus glutinosa) stands growing on riverbanks invaded by two pathogens differing in aggressiveness, namely, Phytophthora uniformis (PU) and Phytophthora x alni (PA). We compared the survival and heritability measures from 72 families originating from six invaded and uninvaded (naive) sites by performing in vitro inoculations. The results from the inoculations were used to assess the relative contribution of host genetic variation on natural selection. We found putative signs of natural selection on alder exerted by PU but not by PA. For PU, we found a higher survival in families originating from invaded sites compared with uninvaded sites. The narrow sense heritability of susceptibility to PU of uninvaded populations was significantly higher than to PA. Simulated data supported the role of heritable genetic variation on natural selection and discarded a high aggressiveness of PA decreasing the transmission rate as an alternative hypothesis for a slow natural selection. Our findings expand on previous attempts of using heritability as a predictor for the likelihood of natural adaptation of naive tree populations to invasive pathogens. Measures of genetic variation can be useful for risk assessment purposes or when managing Phytophthora invasions.

Keywords

adaptation; compartmental SIR model; disease control and pest management; ecology and epidemiology; inoculation; Phytophthora; plant-pathogen interactions; simulation

Published in

Phytopathology
2020, Volume: 110, number: 2, pages: 517-525
Publisher: AMER PHYTOPATHOLOGICAL SOC

SLU Authors

• Redondo, Miguel Angel

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

• Stenlid, Jan

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

Associated SLU-program

SLU Plant Protection Network


UKÄ Subject classification

Ecology
Genetics


Publication identifier

DOI: https://doi.org/10.1094/PHYTO-07-19-0272-R

Permanent link to this page (URI)

https://res.slu.se/id/publ/104487