Characterization of Antagonistic Bacillus methylotrophicus Isolated From Rhizosphere and Its Biocontrol Effects on Maize Stalk Rot

• Published in: Phytopathology Vol. 109; no. 4; pp. 571 - 581
• Main Authors: Cheng, Xingkai, Ji, Xiaoxue, Ge, Yanzhen, Li, Jingjing, Qi, Wenzhe, Qiao, Kang
• Format: Journal Article
• Language: English
• Published: United States 01.04.2019
• Subjects: Antifungal Agents - pharmacology; Bacillus; Biological Control Agents; Fusarium - drug effects; Plant Diseases; Rhizosphere; Zea mays
• DOI: 10.1094/PHYTO-07-18-0220-R
• ISSN: 0031-949X

Stalk rot is one of the most serious and widespread diseases in maize, and effective control measures are currently lacking. Therefore, this study aimed to develop a new biological agent to manage this disease. An antagonistic bacterial strain, TA-1, was isolated from rhizosphere soil and identified as Bacillus methylotrophicus based on morphological and biochemical characterization and 16S ribosomal RNA and gyrB gene sequence analyses. TA-1 exhibited a strong antifungal effect on the growth of Fusarium graminearum mycelium, with 86.3% inhibition at a concentration of 10 CFU per ml. Transmission electron microscopy showed that TA-1 could disrupt the cellular structure of the fungus, induce necrosis, and degrade the cell wall. Greenhouse and field trials were performed to evaluate the biocontrol efficacy of TA-1 on maize stalk rot, and the results of greenhouse experiment revealed that the bacterium significantly reduced disease incidence and disease index. Seeds treated with a 10 CFU ml cell suspension had the highest disease suppression at 86.8%. Results of field trials show that seed bacterization with TA-1 could not only reduce maize stalk rot incidence but also increase maize height, stem diameter, and grain yield. The lipopeptide antibiotics were isolated from the culture supernatants of TA-1 and identified as surfactins and iturins. Consequently, B. methylotrophicus TA-1 is a potential biocontrol agent against maize stalk rot.