Biocontrol potential of fungal endophytes isolated from Thevetia Peruviana (Pers.). K. Schum.

Thevetia peruviana (Pers.) K. Schum., commonly known as yellow oleander, is a toxic evergreen shrub harbouring pharmacologically active compounds with untapped biocontrol potential. The present study provides the first species-level investigation of fungal endophytes from the root, bark, flower, and fruit of T. peruviana, highlighting their enzymatic and biocontrol potential. Seven species have been reported for the first time from Thevetia peruviana: Pseudoascochyta pratensis TP-RF5, Neocosmospora rubicola TP-RF14, Botryotrichum geniculatum TP-BF1, Colletotrichum aotearoa TP-BF4, Botryosphaeria wangensis TP-BF8, Diaporthe sennicola TP-BF12, and Nothophoma macrospora TP-FlF1. Some of them exhibit significant hydrolytic enzyme activity, particularly chitinase and cellulase, and demonstrated substantial inhibition (≥ 50%) of phytopathogens (Fusarium oxysporum, Fusarium fujikuroi, Alternaria calandulae and Aspergillus nishimurae). Correlation analyses revealed a significant positive correlation between chitinase activity and antifungal efficacy, highlighting the prominent role of enzymatic degradation in biocontrol. In contrast, cellulase activity was negatively correlated with Fusarium spp., which might be indicative of complex interactions. Catalase activity negatively correlated with biocontrol potential, indicative of indirect antagonistic effects, whereas amylase, lipase, and protease showed no significant association with antifungal efficacy. Overall, the study underscores the biocontrol and biotechnological potential of T. peruviana endophytic fungi and warrants further investigation of their metabolites and in vivo efficacy.