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

Sang-Jae Won,Jae-Hyun Moon,Henry B Ajuna,Sangtae Lee,Young Sang Ahn,Chaw Ei Htwe Maung,Su-In Choi

doi:10.3390/ijms222011296

Abstract

Leaf blight disease caused by Pestalotiopsis maculans 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 Bacillus velezensis CE 100 in Quercus acutissima Carruth seedlings. B. velezensis 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 P. maculans, leading to mycelial growth inhibition by 54.94%. Inoculation of B. velezensis CE 100 suppressed P. maculans infection and increased seedling survival rate by 1.6-fold and 1.3-fold compared to chemical fertilizer and control, respectively. In addition, B. velezensis CE 100 produced indole-3-acetic acid, which improved root development and nutrient uptake compared to chemical fertilizer and control. Especially, inoculation with B. velezensis CE 100 increased the total nitrogen content of Q. acutissima 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, B. velezensis CE 100 could be applied in the eco-friendly production of high-quality forest seedlings.

Highlights

Quercus spp. (Oaks) are large deciduous trees with a broad spreading crown that are widely grown across Asia, Europe, and North America for their high commercial and environmental value [1,2,3]
Cell wall-degrading enzymes, such as chitinase, β-l,3-glucanase, and protease enproduced by plant growth-promoting bacteria (PGPB), have potential to cause alterations in the structural and functional zyme produced by PGPB, have potential to cause alterations in the structural and funcproperties of fungal cell walls, which inhibits mycelial growth, sporulation, tional properties of fungal cell walls, which mycelial growth, sporulaand plant infection by phytopathogenic fungi
100 reduced leaf blight disease incidence and improved the survival rate of Q. acutissima seedlings compared to the chemical fertilizer treatment (Figure 4). These results suggest that B. velezensis CE 100 can play an effective role as a biocontrol agent against Pestalotiopsis blight in the production of healthy Q. acutissima container seedlings in forest nurseries

Summary

Introduction

Quercus spp. (Oaks) are large deciduous trees with a broad spreading crown that are widely grown across Asia, Europe, and North America for their high commercial and environmental value [1,2,3]. Oaks have been used for various purposes including fuelwood and timber production [3,4], bed logs for mushroom cultivation [5], tannin extraction and bio-oil production [2,6], and acorn production [1]. They have low carbon monoxide peak yield for safe fuel-wood production with reduced risk of gaseous poisoning [4] and are more resistant fire out-break [7]. Quercus acutissima Carruth has recently been among the most planted forest tree species in

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