Understanding the interaction between biocontrol agent Lysobacter enzymogenes and soybean fungal/oomycetes pathogens
Menghao Yu: UNIVERSITY OF ILLINOIS
<div><em>Lysobacter enzymogenes</em> strain C3 (LeC3) is a potential biocontrol agent for plant diseases caused by fungi and oomycetes. Understanding the interaction between LeC3 and soybean pathogens at molecular level could improve its biocontrol efficacy. In this study, we evaluated the effectiveness of LeC3 in inhibiting hyphae growth or spore germination of soybean fungal/oomycete pathogens, and identified and characterized important LeC3 genes during this process. Results showed that LeC3 strongly inhibited hyphae growth or spore germination of<em> Cercospora sojina</em>, <em>Fusarium virguliforme</em>, <em>Macrophomina phaseolina</em>, <em>Phytophthora sojae</em>, <em>Pythium sylvaticum</em>, <em>Rhizoctonia solani</em>, <em>Septoria glycines</em>, and <em>Sclerotinia sclerotiorum</em>, suggesting its broad spectrum activities. Screening a LeC3 mutant library identified 74 mutants that no longer inhibited <em>S. sclerotiorum</em> growth. Characterization of nine selected mutants revealed that these mutants no longer inhibited hyphae growth of <em>S. sclerotiorum</em> and significantly suppressed spore germination of <em>F. virguliforme</em>. Furthermore, production of four extracellular enzymes and secretion of the heat stable antifungal factor (HSAF), a fungal specific antibiotic, was significantly decreased in all nine mutants. Collectively, our findings demonstrated that LeC3 could be very effective in controlling soybean fungal/oomycetes diseases and suggested that the nine genes play critical roles in the production and secretion of extracellular enzymes and HSAF.</div>
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