Tea gray blight disease is a significant threat to the tea industry. In this study, a biological activity approach was utilized to investigate the efficacy of green fungicides from
Magnolia officinalis
stem bark against
Neopestalotiopsis ellipsospora
. The active compounds were isolated and purified, and their structures were elucidated. In vitro and in vivo activity screenings revealed that the n-hexane extract, which contained magnolol and honokiol, exhibited strong activity against
N. ellipsospora
, showing complete inhibition at 100 mg/L. The EC
50
values of magnolol and honokiol were 5.11 and 6.09 mg/L, respectively. Mechanistically, magnolol was found to disrupt
N. ellipsospora
invasion by damaging the cell membrane, increasing permeability, and causing leakage of intracellular substances. Transcriptome analysis revealed that magnolol treatment downregulates membrane-related genes and leads to the enrichment of lipid metabolism pathway genes. This study revealed that magnolol inhibits
N. ellipsospora
growth by affecting lipid metabolism and compromising cell membrane integrity.
Supplementary Information
The online version contains supplementary material available at 10.1038/s41598-024-75310-7.