Analysis of the culturable endophytic fungi in Dalbergia odorifera and screening of the fungi inducing heartwood formation

Introduction This study aimed to investigate the culturable endophytic fungi in the sapwood and heartwood of Dalbergia odorifera , to screen fungi that can promote heartwood formation, and analysis of components involved in the formation of heartwood of D. odorifera induced by Lasiodiplodia theobromae. Methods Fungi were isolated by tissue culture method, identified based on morphological characteristics and ITS sequence analysis, and their induction effect was confirmed by thin-layer chromatography. Non-targeted metabolomics was used to analyze the induced heartwood. Results A total of 109 endophytic fungal strains were isolated and identified from the six samples. Most isolates (71.56%) came from the heartwood, and other isolates (28.44%) came from the sapwood wood. A strain P3BM2 identified as L. theobromae , isolated from the heartwood of D. odorifera , has the best effect in inducing the formation of heartwood. Thin-layer chromatography confirmed that the induced heartwood met pharmacopeial standards, and its dimensions exceeded those of the control group. Compared to the control, L. theobromae inoculation activated specific differential metabolic pathways. Discussion Endophytic fungi are involved in the heartwood formation of D. odorifera . In this study, we isolated and identified the culturable endophytic fungi from D. odorifera , and demonstrated that L. theobromae can promote heartwood formation in this species. This research provides a theoretical basis for the fungal-mediated induction of high-quality heartwood formation in D. odorifera .