Grasses and Epichloë endophytes often form mutualistic symbiotic defence systems. Studies have shown Epichloë endophytes improve resistance of host plants to airborne diseases. However, whether endophytes affect soil-borne disease resistance of host or neighbouring non-host plants remains unclear. We used endophyte-infected (EI) and endophyte-free (EF) Achnatherum sibiricum as host grass, Leymus chinensis as non-host grass, and Rhizoctonia solani as pathogen to explore the effects of endophyte infection on disease resistance of host and neighbouring non-host grasses. To clarify the contribution of root exudates to disease resistance of the non-host grass, three different root separation methods were employed between host and non-host plants: plastic barrier (PB), nylon mesh barrier (NL, allowing root exudates to pass through), or no barrier (NB). Epichloë endophytes decreased the disease index (DI) of the host A. sibiricum and reduced pathogen abundance in both host roots and soil. The DI of L. chinensis was affected by the interaction between root separation and endophyte infection. Under NL and NB treatments, the DI of L. chinensis with an EI neighbour was significantly lower than that with an EF neighbour, indicating that endophytic fungi can alleviate disease in non-host plants by influencing root exudates. Additionally, endophytic fungi increased the content of total phenolic compounds and salicylic acid in L. chinensis through activation of host root exudates, which could be one reason for the reduced DI of L. chinensis. Upon analysing root exudate components of the host, we found 2,4-di-tert-butylphenol (DTBP) and dibutyl phthalate (DBP) were the main antifungal compounds mediated by endophyte infection. Epichloë endophytes improved soil-borne disease resistance of the host and enhanced resistance of the neighbouring non-host grass through host root exudates; overall, host and non-host plants showed "associational resistance" to soil-borne diseases. This study highlights that Epichloë endophytes could potentially serve as efficient biological control agents against R. solani-associated diseases in grassland communities.
{"title":"Epichloë endophyte-infected Achnatherum sibiricum and neighbouring non-host grasses exhibit associational resistance to soil-borne diseases.","authors":"X Ge, N Li, J Zhang, X Fan, L Chen, N Zhao, A Ren","doi":"10.1111/plb.70112","DOIUrl":"https://doi.org/10.1111/plb.70112","url":null,"abstract":"<p><p>Grasses and Epichloë endophytes often form mutualistic symbiotic defence systems. Studies have shown Epichloë endophytes improve resistance of host plants to airborne diseases. However, whether endophytes affect soil-borne disease resistance of host or neighbouring non-host plants remains unclear. We used endophyte-infected (EI) and endophyte-free (EF) Achnatherum sibiricum as host grass, Leymus chinensis as non-host grass, and Rhizoctonia solani as pathogen to explore the effects of endophyte infection on disease resistance of host and neighbouring non-host grasses. To clarify the contribution of root exudates to disease resistance of the non-host grass, three different root separation methods were employed between host and non-host plants: plastic barrier (PB), nylon mesh barrier (NL, allowing root exudates to pass through), or no barrier (NB). Epichloë endophytes decreased the disease index (DI) of the host A. sibiricum and reduced pathogen abundance in both host roots and soil. The DI of L. chinensis was affected by the interaction between root separation and endophyte infection. Under NL and NB treatments, the DI of L. chinensis with an EI neighbour was significantly lower than that with an EF neighbour, indicating that endophytic fungi can alleviate disease in non-host plants by influencing root exudates. Additionally, endophytic fungi increased the content of total phenolic compounds and salicylic acid in L. chinensis through activation of host root exudates, which could be one reason for the reduced DI of L. chinensis. Upon analysing root exudate components of the host, we found 2,4-di-tert-butylphenol (DTBP) and dibutyl phthalate (DBP) were the main antifungal compounds mediated by endophyte infection. Epichloë endophytes improved soil-borne disease resistance of the host and enhanced resistance of the neighbouring non-host grass through host root exudates; overall, host and non-host plants showed \"associational resistance\" to soil-borne diseases. This study highlights that Epichloë endophytes could potentially serve as efficient biological control agents against R. solani-associated diseases in grassland communities.</p>","PeriodicalId":220,"journal":{"name":"Plant Biology","volume":" ","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145385548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}