Biological Control of Leaf Blight Disease Caused by Pestalotiopsis maculans and Growth Promotion of Quercus acutissima Carruth Container Seedlings Using Bacillus velezensis CE 100

Abstract

Leaf blight disease caused by <i>Pestalotiopsis</i><i>maculans</i> lead to deleterious losses in the quality of forest container seedlings. The use of plant growth-promoting bacteria provides a promising strategy to simultaneously control diseases and enhance forest seedling production. This study investigated the biocontrol of leaf blight disease and growth promotion potential of <i>Bacillus velezensis</i> CE 100 in <i>Quercus acutissima</i> Carruth seedlings. <i>B. velezensis</i> CE 100 produced cell wall degrading enzymes, such as chitinase, β-l,3-glucanase, and protease, which caused cell wall lysis and hyphae deformation of <i>P. maculans</i>, leading to mycelial growth inhibition by 54.94%. Inoculation of <i>B. velezensis</i> CE 100 suppressed <i>P. maculans</i> infection and increased seedling survival rate by 1.6-fold and 1.3-fold compared to chemical fertilizer and control, respectively. In addition, <i>B</i>. <i>velezensis</i> CE 100 produced indole-3-acetic acid, which improved root development and nutrient uptake compared to chemical fertilizer and control. Especially, inoculation with <i>B. velezensis</i> CE 100 increased the total nitrogen content of <i>Q. acutissima</i> seedlings, improved the chlorophyll index in the leaves, and increased seedling biomass by 1.3-fold and 2.2-fold compared to chemical fertilizer and control, respectively. Thus, <i>B. velezensis</i> CE 100 could be applied in the eco-friendly production of high-quality forest seedlings.