Endophytic bacteria isolated from a weed plant as a potential biocontrol agent against stem end rot pathogen of pitaya in Vietnam

Abstract

Abstract Background Stem end rot (SER) disease caused by Alternaria alternata is one of the main fungal diseases in pitaya and other crops in Nam Dinh, Vietnam, that leads to extensive yield and economic losses. Biocontrol of SER, using endophytic bacteria, is environmentally friendly and compatible with other control measures. Hence, it is emerging as an alternative disease management strategy in sustainable agriculture. This study aimed to screen antagonistic bacteria isolated from the weed, Eleusine indica, with the potential to manage SER. Results A total of 16 endophytes were isolated from the stems, leaves, and roots of the weed, E. indica. Of those, 6 strains presented antagonistic effects against A. alternata growth, and one isolate, EI-15, showed a significant inhibitory effect on SER. In addition, analyzing the 16S rDNA sequence indicated that EI-15 was a strain of Bacillus amyloliquefaciens. Moreover, the results of the antagonistic spectrum assay showed that EI-15 significantly inhibited some plant and fruit tree pathogens, especially the suppression of A. alternata. Notably, the culture filtrate of strain EI-15 exhibited in vitro apparent activity against A. alternata. Furthermore, an in vivo antagonistic experiment of EI-15 on pitaya twig showed a significant reduction of lesion on twigs than the control. Conclusions Overall, this study suggested the potential application of the EI-15 strain as a biological agent and needs to be further studied in the field to control SER.

Keywords

• Alternaria alternata
• Eleusine indica
• Endophyte bacterium
• 16S rDNA
• Bacillus amyloliquefaciens