Isolation, Identification, and Diversity Analysis of Endophytic Fungi from Sweetpotato

Endophytic fungi contribute substantially to plant health, yet the diversity, community composition, and tissue distribution of culturable fungal endophytes in sweetpotato remain poorly characterized. In this study, endophytic fungi were isolated from roots, old stems, tender stems, petioles, and leaves of the scab-resistant leafy variety ‘Guangcaishu 16–19’, the scab-susceptible leafy variety ‘Guangcaishu No. 5’, and the tuberous variety ‘Guangshu 87’ were identified based on morphological characteristics and ITS sequencing. ITS sequencing identified 492 fungal isolates belonging to 63 putative taxa in 31 genera. Colletotrichum was the dominant genus in the leafy varieties, whereas Chaetomium was dominant in the tuberous variety. The isolated endophytic fungi were widely distributed and tissue-specific, with genus-level distribution following the pattern “leaves and stems > roots”. Alpha diversity followed the order ‘Guangcaishu 16–19’ > ‘Guangcaishu No. 5’ > ‘Guangshu 87’. The fungal communities of the leafy varieties were the most similar, and their root-associated communities exhibited higher alpha diversity than those of the tuberous variety. In addition, scab-resistant varieties exhibited higher endophytic fungal diversity. Overall, endophytic fungal communities in sweetpotato exhibited high alpha diversity, and significant differences in community structure were observed among variety tissues. These findings provide culturable fungal resources for future screening of beneficial endophytic fungi, bioactive metabolites, and potential biocontrol agents.