Bacillus strain selection with plant growth-promoting mechanisms as potential elicitors of systemic resistance to gray mold in pepper plants

Certain soil bacteria produce beneficial effects on the growth and health of plants; hence, their use is steadily increasing. Five strains of <i>Bacillus</i> with plant growth-promoting potential were selected in this study, which produced indole-3-acetic acid levels below 50 µg.mL^-1. On the other hand, while only strains M8 and M15 dissolved phosphorus, the latter was the only strain that did not produce siderophores. Only strains M8 and M16 significantly inhibited the <i>in vitro</i> growth of <i>Botrytis cinerea</i> and <i>Fusarium solani</i> phytopathogens, whose inhibition ranges fluctuated between 60% and 63% for strains M8 and M16 against <i>B</i>. <i>cinerea</i> and between 40% and 53% for strains M8 and M16 against <i>F</i>. <i>solani</i>. Based on these results, the need to implement resistance induction against gray mold on pepper plants was determined using strains M8 and M16. In this case, strain M16 inhibited the propagation of the necrotic spot by approximately 70%, whereas strain M8 significantly reduced the superoxide dismutase activity in systemic leaves, which substantially increased in plants inoculated with strain M8 and infected with the pathogen. Accordingly, the use of native rhizobacteria may entail biotechnological progress for the integrated management of crops in agriculture industry.