AUTHOR=Chen Xue , Zhang Yin , Chao ShengQian , Song LiLi , Wu GuoGan , Sun Yu , Chen YiFan , Lv BeiBei 

TITLE=Biocontrol potential of endophytic Bacillus subtilis A9 against rot disease of Morchella esculenta

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1388669

DOI=10.3389/fmicb.2024.1388669

ISSN=1664-302X

ABSTRACT=<sec id="sec1"><title>Introduction</title><p><italic>Morchella esculenta</italic> is a popular edible fungus with high economic and nutritional value. However, the rot disease caused by <italic>Lecanicillium aphanocladii</italic>, pose a serious threat to the quality and yield of <italic>M. esculenta</italic>. Biological control is one of the effective ways to control fungal diseases.</p></sec><sec id="sec2"><title>Methods and results</title><p>In this study, an effective endophytic <italic>B. subtilis</italic> A9 for the control of <italic>M. esculenta</italic> rot disease was screened, and its biocontrol mechanism was studied by transcriptome analysis. In total, 122 strains of endophytic bacteria from <italic>M. esculenta</italic>, of which the antagonistic effect of <italic>Bacillus subtilis</italic> A9 on <italic>L. aphanocladii</italic> G1 reached 72.2% <italic>in vitro</italic> tests. Biological characteristics and genomic features of <italic>B. subtilis</italic> A9 were analyzed, and key antibiotic gene clusters were detected. Scanning electron microscope (SEM) observation showed that <italic>B. subtilis</italic> A9 affected the mycelium and spores of <italic>L. aphanocladii</italic> G1. In field experiments, the biological control effect of <italic>B. subtilis</italic> A9 reached to 62.5%. Furthermore, the transcritome profiling provides evidence of <italic>B. subtilis</italic> A9 bicontrol at the molecular level. A total of 1,246 differentially expressed genes (DEGs) were identified between the treatment and control group. Gene Ontology (GO) enrichment analysis showed that a large number of DEGs were related to antioxidant activity related. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the main pathways were Nitrogen metabolism, Pentose Phosphate Pathway (PPP) and Mitogen-Activated Protein Kinases (MAPK) signal pathway. Among them, some important genes such as carbonic anhydrase CA (H6S33_007248), catalase CAT (H6S33_001409), tRNA dihydrouridine synthase DusB (H6S33_001297) and NAD(P)-binding protein NAD(P) BP (H6S33_000823) were found. Furthermore, <italic>B. subtilis</italic> A9 considerably enhanced the <italic>M. esculenta</italic> activity of Polyphenol oxidase (POD), Superoxide dismutase (SOD), Phenylal anineammonia lyase (PAL) and Catalase (CAT).</p></sec><sec id="sec3"><title>Conclusion</title><p>This study presents the innovative utilization of <italic>B. subtilis</italic> A9, for effectively controlling <italic>M. esculenta</italic> rot disease. This will lay a foundation for biological control in <italic>Morchella</italic>, which may lead to the improvement of new biocontrol agents for production.</p></sec>