Terpenoids are involved in the expression of systemic‐induced resistance in Austrian pine

• Published in: Plant, cell and environment Vol. 47; no. 6; pp. 2206 - 2227
• Main Authors: Ghosh, Soumya K., Ishangulyyeva, Guncha, Erbilgin, Nadir, Bonello, Pierluigi
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.06.2024
• Subjects: Antifungal activity; Ascomycota - physiology; Benzaldehyde; Bioassays; biochemical defense; Blight; Carbon sources; conifer; Correlation; Disease Resistance; Dodecanol; fungal pathogen; Fungicides; induced resistance; Limonene; Metabolites; Pinene; Pinus - drug effects; Pinus - metabolism; Pinus - microbiology; Plant Diseases - microbiology; Seedlings; Seedlings - drug effects; Seedlings - metabolism; Stems; temporal; Terpenes; Terpenes - metabolism; Terpenes - pharmacology; volatiles; Wounding; biochemical defense; fungal pathogen; induced resistance; wounding; conifer; temporal; volatiles
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.14875

Terpenoids are defense metabolites that are induced upon infection or wounding. However, their role in systemic‐induced resistance (SIR) is not known. Here, we explored the role of terpenoids in this phenomenon at a very early stage in the interaction between Austrian pine and the tip blight and canker pathogen Diplodia pinea. We induced Austrian pine saplings by either wounding or inoculating the lower stems with D. pinea. The seedlings were then challenged after 12 h, 72 h, or 10 days with D. pinea on the stem 15 cm above the induction. Lesion lengths and terpenoids were quantified at both induction and challenge locations. Key terpenoids were assayed for antifungal activity in in vitro bioassays. SIR increased with time and was correlated with the inducibility of several compounds. α‐Pinene and a cluster of β‐pinene, limonene, benzaldehyde, dodecanol, and n‐dodecyl acrylate were positively correlated with SIR and were fungistatic in vitro, while other compounds were negatively correlated with SIR and appeared to serve as a carbon source for D. pinea. This study shows that, overall, terpenoids are involved in SIR in this system, but their role is nuanced, depending on the type of induction and time of incubation. We hypothesize that some, such as α‐pinene, could serve in SIR signaling. Summary statement Trees can resist recurring pathogenic attacks using memory of successful prior encounters with pest or pathogens. Here we show that pathogenic induction results in systemic and selective accumulation of certain terpenoids and other non‐terpenoids in trees conferring higher resistance against newer infection.