Endophytic <i>Beauveria bassiana</i> Induces Oxidative Stress and Enhances the Growth of <i>Fusarium oxysporum</i>-Infected Tomato Plants

• Published in: Plants
• Main Authors: Felix Nchu, Neo Macuphe, Ilyaas Rhoda, Lee-Ann Niekerk, Gerhard Basson, Marshall Keyster, Ninon G. E. R. Etsassala
• Format: Article
• Language: English
• Published: MDPI AG 2022-11-01
• Subjects: endophytic <i>Beauveria bassiana</i>; <i>Fusarium oxysporum</i>; tomatoes; antioxidant activities; oxidative stress
• Online Access: https://www.mdpi.com/2223-7747/11/22/3182

Studying the mechanisms through which endophytic fungi confer protection to host plants against parasites will contribute toward elucidating the endophytic fungi–plant–pathogen relationship. In this study, we evaluated the effects of endophytic <i>Beauveria bassiana</i> on the antioxidant activity, oxidative stress, and growth of tomatoes infected with the fusarium wilt pathogen, <i>Fusarium oxysporum</i> f. sp. lycopersici (FOL). Tomato seedlings were inoculated with <i>B. bassiana</i> conidia and then contaminated with FOL experimentally. Four treatments (Control [T1], FOL only [T2], <i>B. bassiana</i> only [T3], and <i>B. bassiana</i> and FOL [T4]) were assessed. The plants from the <i>B. bassiana</i> and FOL treatment (T4) were significantly taller (DF = 3, 56; <i>p</i> < 0.001) and produced more leaves and aerial part biomass than those treated with only FOL (T2). Remarkably, plants in the two treatments with FOL (T2 and T4) had the lowest antioxidant activities; meanwhile, plants from the FOL treatment (T2) had the lowest ROS (superoxide and hydroxyl radicals) contents. Broadly, strong positive correlations between ROS and all the plant growth parameters were recorded in this study. While the current results revealed that the endophytic entomopathogen <i>B. bassiana</i> enhanced antioxidant capacity in plants, it did not improve the antioxidant capacity of <i>F. oxysporum</i>-infected plants. It is possible that the pathogenic FOL employed a hiding strategy to evade the host immune response and the antagonistic actions of endophytic <i>B. bassiana</i>. In conclusion, <i>B. bassiana</i> inoculum enhanced the growth of tomatoes infected with FOL, induced higher oxidative stress in both <i>F. oxysporum</i>-infected and -uninfected tomatoes, and improved antioxidant activities in plants inoculated with <i>B. bassiana</i> only.