Isolation and in vitro Evaluation of Antagonistic Bacterial Endophytes from Eleusine coracana (L.) Gaertn. against Magnaporthe oryzae

Abstract

Pyricularia oryzae (syn. M. oryzae), the causative agent of blast disease, is among the most destructive fungal pathogens threatening rice production and other cereal crops worldwide. The search for environmentally sustainable alternatives to synthetic fungicides has increased interest in endophytic bacteria as potential biological control agents. In the current study, endophytic bacterial isolates obtained from disease-resilient finger millet were evaluated for their antagonistic activity against P. oryzae using dual-culture, cell-free culture filtrate, and conidial germination assays. Among the tested isolates, AL2 and AN6 exhibited the strongest antagonistic activity in dual culture, inhibiting mycelial growth by more than 82%, while AN2 showed moderate inhibition (52.07%). Cell-free culture filtrates suppressed fungal growth in a concentration-dependent manner across 10%-30% (v/v), with isolate AN6 demonstrating the highest inhibition of mycelial growth (85.24%) at a concentration of 30%, followed by AL2 and AN2. Similarly, the culture filtrates markedly reduced conidial germination after 12 h of incubation. At the highest concentration, AN6 reduced germination to 4.33%, followed by AL2 (6.33%) and AN2 (14.33%), compared with the untreated control. These findings identify finger millet-associated endophytes, particularly isolate AN6, as promising candidates for the biological management of rice blast disease. Further greenhouse and field evaluations are required to confirm their efficacy under natural conditions.