Diversity and Antagonistic Potential of Endophytic Fungi Associated with Cannabis sativa in Thailand

Cannabis sativa L. is a multipurpose plant widely cultivated for fiber, food, medicinal products, and the production of bioactive compounds, including psychoactive cannabinoids. Fungal endophytes are a promising source of antimicrobial compounds used for biological control and sustainable crop production. However, the fungal endophytes associated with C. sativa have been poorly investigated, and their biological activities are still largely unexplored. Thus, this study aimed to identify fungal endophytes from C. sativa (marijuana and hemp biotypes) and to screen for their antagonistic activities against some plant pathogens. Based on ITS sequence analysis, a total of 103 fungal endophyte isolates (21 genera) were preliminarily identified from both biotypes, including 62 isolates (13 genera) from hemp and 41 isolates (nine genera) from marijuana. Fusarium was the dominant genus found in hemp (45%), while Nigrospora was the dominant genus isolated from marijuana (32%). Ten selected fungal endophytes were evaluated for in vitro antagonistic activity against four bacterial pathogens, Pectobacterium spp. (PC 01 and PC 02) and Ralstonia solanacearum (RA 01 and RA 02), and four fungal pathogens, Fusarium solani (FU 01), F. oxysporum (FU 02), and Sclerotium sp. (SC 01 and SC 02), all of which are causal agents of potato diseases. Among the tested fungal endophytes, Colletotrichum sp. (SLLC-M24) and Nigrospora sp. (SLLC-H15) exhibited the strongest antifungal activity against Fusarium spp. (FU 01 and FU 02), with inhibition rates ranging from 56 to 64%. In addition, Pestalotiopsis sp. (SLLC-H5) demonstrated effective antibacterial activity against all tested bacterial pathogens, producing inhibition zones ranging from 19 to 23 mm. This finding represents an important step toward discovering novel and promising endophytes associated with Cannabis and their biological control potential for utilization in sustainable agriculture.