Screening of plant growth-promoting endophytic bacteria from the maize roots for biocontrol of stewart wilt disease

Abstract

Bacterial endophytes colonize and are widely related to plant interior tissues. They provide maize with various advantages by functioning as growth stimulants and disease protectors. This research is intended to verify the hypothesis that the maize root bacteria are potential plant growth-promoting and Stewart wilt disease-suppressor. Fifty-three endophytic root bacteria from various maize varieties cultivated in South Sumatra and West Java production centres were isolated and evaluated. Initial screening for biosafety assays has selected 24 isolates for further analysis. The antagonistic activity of a bacterial endophyte against Pantoea stewartii subsp. stewartii was evaluated. Endophytic bacteria were selected for indole-3-acetic acid (IAA) synthesizing, nitrogen fixation, solubilizer-phosphate capacity, lytic-enzymes production, and pathogens inhibition. Antibiotics were produced by approximately 50% of isolates, volatile organic compounds by more than 80% of isolates, IAA by up to 91.7% of isolates, N fixation by 79.2% of isolates, phosphate solubilization by more than 50% of isolates, and protease by only 20.8% of isolates. Six isolates have been successfully selected using the analytical hierarchy process (AHP), which have a maximum score of AHP, including BU-5, JCJ-7, MS-X, JCB-1, JCJ-3, and JCJ-2. The highest inhibition of pathogen growth through antimicrobial activity occurs in isolates BU-5 and JCJ-7 (100%), while JCJ-2 has maximum VOC activity (80.56%) and IAA production (32.78 ppm). Meanwhile, solubilizing phosphate index and protease production are the highest in the JCJ-3 isolate. This paper offers scientific information for upcoming studies on endophytic bacteria to increase maize productivity and disease control.