Biocontrol Potential of a Novel Endophytic Bacterium From Mulberry (Morus) Tree

Abstract

Mulberry (Morus) is an economically important woody tree that is suitable for use in sericulture as forage and in medicine. However, this broad-leaved tree is facing multiple threats ranging from phytopathogens to insect pests. Here, a Gram-positive, endospore-forming bacterium (ZJU1) was frequently isolated from healthy mulberry plants by screening for foliar endophytes showing antagonism against pathogens and pests. Whole-genome sequencing and annotation resulted in a genome size of 4.06 Mb and classified the bacterium as a novel strain of Bacillus amyloliquefaciens that has rarely been identified from tree leaves. An integrative approach combining traditional natural product chemistry, activity bioassays, and high-resolution mass spectrometry confirmed that strain ZJU1 uses a blend of antimicrobials including peptides and volatile organic compounds to oppose Botrytis cinerea, a major phytopathogenic fungus causing mulberry gray mold disease. We showed that the inoculation of endophyte-free plants with ZJU1 significantly decreased both leaf necrosis and mortality under field conditions. In addition to the direct interactions of endophytes with foliar pathogens, in planta studies suggested that the inoculation of endophytes also induced plant systemic defense, including high expression levels of mulberry disease resistance genes. Moreover, when applied to the generalist herbivore Spodoptera litura, ZJU1 was sufficient to reduce the pest survival rate below 50%. A previously undiscovered crystal toxin (Cry10Aa) could contribute to this insecticidal effect against notorious lepidopteran pests. These unique traits clearly demonstrate that B. amyloliquefaciens ZJU1 is promising for the development of successful strategies for biocontrol applications. The search for new plant-beneficial microbes and engineering microbiomes is therefore of great significance for sustainably improving plant performance.

Potential of microbial endophytes to enhance the resistance to postharvest diseases of fruit and vegetables

“…showed that the number of endophytic actinobacteria in cucumber ( Cucumis sativus L.) infected with Fusarium wilt was more than that in the root of healthy cucumber, and the endophytic strain HAAG3‐15 isolated from the root had strong antifungal ability against Fusarium wilt and broad‐spectrum antifungal activity. Bacillus amyloliquefaciens ZJU1 isolated from mulberry ( Morus alba L.) leaves can inhibit fungal diseases in mulberry trees, induce high expression of disease resistance genes in mulberry, and secrete secondary metabolites affecting growth and spore germination of B. cinerea and other fungal diseases 121 . An endophytic Burkholderia SSG isolated from Justin Brouwers boxwood ( Buxus sempervirens L.) leaves reduces incidence rate of 90% boxwood blight 122 .…”

Complete Genome Sequence of Bacillus amyloliquefaciens EA19, an Endophytic Bacterium with Biocontrol Potential Isolated from Erigeron annuus

“…Endophytic bacteria play an important role in suppressing plant diseases ( 1 ). Bacillus amyloliquefaciens , a plant-associated bacterium, can be found in plant organs and exhibits antifungal activities against plant pathogens ( 2 – 4 ). Genome analysis helps to elucidate the gene clusters involved in the biosynthesis of active secondary metabolites of B. amyloliquefaciens ( 4 ).…”

Fungal Inhibition of Agricultural Soil Pathogen Stimulated by Nitrogen-Reducing Fertilization

“…Crop rotation is a slow method for reducing pathogen density in soil, making it unsuitable when severe disease breakout ( Chellemi et al, 2016 ). Biocontrol bacteria are receiving increasing attention as a potential alternative to traditional methods for controlling plant diseases ( Choi et al, 2020 ; Ogunnaike et al, 2021 ; Ahmed et al, 2022 ), based on being harmless, effective, and sustainable ( Xie et al, 2020 ). Previous studies have identified various biocontrol agents including Bacillus spp.…”