Identification and characterization of genes in antagonism against soybean fungal pathogens by lysobacter enzymogenes

Lysobacter enzymogenes;Biological control;Molecular mechanism

Yu, Menghao ; Mideros, Santiago, ; ,Jamann, Tiffany ; Zhao ; Youfu

关键词: Lysobacter enzymogenes;    Biological control;    Molecular mechanism;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/98296/YU-THESIS-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Lysobacter enzymogenes strain C3 (LeC3) is a potential biocontrol agent for various fungal, oomycete, bacterial, and nematode plant diseases. Understanding the molecular mechanism of LeC3 antagonism against multiple pathogens could greatly improve its biocontrol efficacy. In this study, a library containing 948 transposon-insertion mutants of LeC3 was generated and screened to identify genes associated with LeC3 antagonism against fungal pathogens. Results showed that 141 mutants showed significant decrease in inhibiting hyphae growth of the white mold pathogen (Sclerotinia sclerotiorum). Among them, 74 mutants no longer inhibited S. sclerotiorum hyphae growth. The insertion sites for 50 out of these 74 mutants were determined by inverse or RATE PCR and sequencing. Nine mutants were selected for further characterization.These nine mutants were partially recovered in their abilities in inhibiting hyphae growth of the white mold pathogen by introducing plasmids containing corresponding genes. Results also showed that all nine mutants exhibited significantly decreased abilities in suppressing spore germination of the sudden death syndrome pathogen (Fusarium virguliforme), and in the production of four extracellular enzymes (protease, lipase, cellulase, and chitinase). In addition, the production of the heat stable antifungal factor (HSAF), a fungal specific antibiotic produced by LeC3, was determined in these nine mutants using HPLC and all nine mutants showed significant decrease in HSAF production or secretion. Collectively, our findings suggest that the nine genes identified and characterized in LeC3 play important roles in the antagonism against fungal pathogens probably by influencing the production and/or secretion of extracellular enzymes and HSAF.