Isolation of strawberry endophytic bacteria and investigation of their antifungal effects on Colletotrichum nymphaeae, the causal agent of strawberry anthracnose

In this study, three nonpathogenic endophytic bacterial isolates recovered from Fragaria × ananassa stolon and petal and their antagonistic activity was evaluated against Colletotrichum nymphaeae, the causal agent of strawberry anthracnose under in vitro, in vivo, and greenhouse conditions. Bacterial isolates were identified as Bacillus spp. using a combination of phenotypic, biochemical properties and molecular phylogenetic analysis of the 16S rDNA gene sequence. The living cells of bacterial isolates inhibited the mycelial growth of C. nymphaeae using dual culture method and inhibition percentage was evaluated as 41.87, 50, and 54.92 % in MarG2, MarD40 and MarD35, respectively. The volatile compounds (VOCs) produced by bacterial isolates inhibited the mycelial growth of C. nymphaeae and the highest inhibition was observed in MarD35 isolate (24.7%). Moreover, the cell free culture filtrates of bacterial isolates reduced the mycelial growth and conidial germination of pathogen and the highest inhibition was observed in MarG2 (34.96%) on mycelial growth and in MarD35 (52.07%) on conidial germination. The living cells of bacterial isolates decreased anthracnose fruit rot at postharvest and the highest inhibition was observed in MarD40 (85.63%) and MarD35 (81.72%), respectively. Furthermore, disease severity of strawberry anthracnose by bacterial isolates was reduced using drenching soil and plant spraying techniques. The findings of this study showed that bacterial isolates have the ability to prevent the growth of fungal pathogen under in vitro, in vivo and greenhouse conditions.