Endophytic bacteria derived from the desert-spurge (Euphorbia antiquorum L.) suppress Fusarium verticillioides, the causative agent of maize ear and root rot

Fungal plant pathology is a huge concern to the agricultural industry across the globe. Fusarium verticillioides is recognized as the most widespread and severe pathogenic fungus associated with maize production. This study aimed to investigate the antagonistic potential of twenty-seven (27) endophytic bacteria from the Desert spurge (Euphorbia antiquorum L.) against Fusarium verticillioides causing ear and root rot in maize. The in vitro screening revealed that six (6) bacteria restricted Fusarium verticillioides mycelial growth upon direct confrontation, resulting in a 68.59% reduction and nine (9) inhibited via the production of VOMs (71.7% mycelial growth reduction). In vitro, all the tested bacteria produced several extracellular enzymes and various plant growth-promoting factors, such as indole acetic acid (IAA), ammonia, siderophores and solubilized phosphate. In the greenhouse experiment, potent endophytic bacteria significantly lowered the severity of ear and root rot disease caused by F. verticillioides in maize seedlings, with Citrobacter fruendii LPR4(+) being the most effective. Moreover, the protective effect was strongly associated with PGP aptitudes, which was manifested by increases in root and shoot development by up to 79 and 28%, respectively, as well as guaiacol peroxidase and phenylalanine ammonialyase specific activities. The current data constitute the starting point toward an ecological solution to control ear and root rot disease in maize.

Automated summary

Fungal plant pathology, especially Fusarium verticillioides, poses a significant threat to maize production. This study investigated the antagonistic potential of 27 endophytic bacteria against F. verticillioides causing ear and root rot disease in maize. In vitro screening revealed that certain bacteria restricted fungal growth directly or via the production of volatile organic compounds. These bacteria also produced extracellular enzymes and plant growth-promoting factors. In a greenhouse experiment, Citrobacter fruendii LPR4(+) exhibited the best protective effect against F. verticillioides, leading to improved root and shoot development.