TY - JOUR
T1 - Linking symbioses with intrinsic chemical defences in conifers
T2 - Fungal-mediated resistance against an invasive pathogen
AU - Bullington, Lorinda
AU - Martin, Emily
AU - Erbilgin, Nadir
AU - Kennedy, Peter
AU - Kegley, Angelia
AU - Larkin, Beau
AU - Lekberg, Ylva
AU - Six, Diana
AU - Sniezko, Richard
N1 - Publisher Copyright:
© 2024 The Author(s). Journal of Applied Ecology © 2024 British Ecological Society. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.
PY - 2024/12
Y1 - 2024/12
N2 - Invasive pathogens threaten the sustainability of forest ecosystems globally. Trees possess intrinsic pathogen defence mechanisms, including major gene resistance (MGR) and quantitative disease resistance (QDR). Plant-symbiotic fungi can enhance tree defences, generating far-reaching ecosystem impacts. However, the specific contributions of various fungal guilds to this symbiont-mediated resistance remain unclear. In this study, we inoculated six Pinus monticola seedling families exhibiting resistance (MGR or QDR) or high susceptibility to the introduced invasive pathogen Cronartium ribicola, the causative agent of white pine blister rust (WPBR), with endophytic and ectomycorrhizal fungi, either alone or in combination (symbiont treatments), in an open-air greenhouse study. Over a period of 25 months, we monitored the growth, foliar terpene defences, and disease progression in trees before and after C. ribicola infection and in trees inoculated with the symbionts but never inoculated with C. ribicola. We observed enhanced inducible host defences and evidence of defensive priming in response to symbiont treatments. In WPBR-free control treatments, differences in pine defences coincided with an increased seedling growth rate. For WPBR-infected seedlings, symbiont treatments reduced disease symptoms in seedlings with QDR and to a lesser extent in susceptible families, but not in those with MGR. Furthermore, disease symptoms correlated with variations in terpene composition. Synthesis and applications: Interactions with fungal symbionts should be considered when breeding native trees for resistance against invasive pathogens. Our study underscores the capacity of endophytic and ectomycorrhizal fungi to enhance tree growth and defence while also reducing disease symptoms. We also show that fungi can induce long-lasting changes in conifer foliar terpenes, suggesting potential applications in tree protection from invasive pathogens.
AB - Invasive pathogens threaten the sustainability of forest ecosystems globally. Trees possess intrinsic pathogen defence mechanisms, including major gene resistance (MGR) and quantitative disease resistance (QDR). Plant-symbiotic fungi can enhance tree defences, generating far-reaching ecosystem impacts. However, the specific contributions of various fungal guilds to this symbiont-mediated resistance remain unclear. In this study, we inoculated six Pinus monticola seedling families exhibiting resistance (MGR or QDR) or high susceptibility to the introduced invasive pathogen Cronartium ribicola, the causative agent of white pine blister rust (WPBR), with endophytic and ectomycorrhizal fungi, either alone or in combination (symbiont treatments), in an open-air greenhouse study. Over a period of 25 months, we monitored the growth, foliar terpene defences, and disease progression in trees before and after C. ribicola infection and in trees inoculated with the symbionts but never inoculated with C. ribicola. We observed enhanced inducible host defences and evidence of defensive priming in response to symbiont treatments. In WPBR-free control treatments, differences in pine defences coincided with an increased seedling growth rate. For WPBR-infected seedlings, symbiont treatments reduced disease symptoms in seedlings with QDR and to a lesser extent in susceptible families, but not in those with MGR. Furthermore, disease symptoms correlated with variations in terpene composition. Synthesis and applications: Interactions with fungal symbionts should be considered when breeding native trees for resistance against invasive pathogens. Our study underscores the capacity of endophytic and ectomycorrhizal fungi to enhance tree growth and defence while also reducing disease symptoms. We also show that fungi can induce long-lasting changes in conifer foliar terpenes, suggesting potential applications in tree protection from invasive pathogens.
KW - blister rust disease
KW - Cronartium ribicola
KW - defensive priming
KW - ectomycorrhizal fungi
KW - endophytes
KW - induced defences
KW - Pinus monticola
KW - terpenes
UR - http://www.scopus.com/inward/record.url?scp=85208440362&partnerID=8YFLogxK
U2 - 10.1111/1365-2664.14816
DO - 10.1111/1365-2664.14816
M3 - Article
AN - SCOPUS:85208440362
SN - 0021-8901
VL - 61
SP - 3126
EP - 3138
JO - Journal of Applied Ecology
JF - Journal of Applied Ecology
IS - 12
ER -