Combined transcriptome and metabolome analysis of Hua in response to infection.

The fungal pathogen , first identified as the causative agent of gray mold disease in China, has become a critical biotic constraint limiting the sustainable production of Hua in major cultivation regions. To investigate the physiological reactions and transcriptome gene changes of after infection, in this study, we investigated the defense enzyme activity, transcriptome differential genes (DEGs), and differential metabolites (DAMs) of . When invaded the leaves of , the activities of phenylalanine deaminase (PAL), catalase (CAT), and peroxidase (POD) increased. The most responsive Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in the transcriptome were plant-pathogen interaction, plant hormone signal transduction, the mitogen-activated protein kinase (MAPK) signaling pathway, and phenylpropanoid biosynthesis (phenylpropanoid biosynthesis) metabolic pathways. Among the DEGs, AP2 ERF-ERFs, WRKYs, and C2H2 were highly predictive of transcription factors (TFs), with WRKYs being important TFs in the MAPK pathway. In the metabolome, coumaric acid, α-linolenic acid, and jasmonic acid (JA) are important metabolites that respond to infection. Correlation analysis between the transcriptome and metabolome revealed that phenylpropanoid metabolism and α-linolenic acid metabolism pathways are associated with the most significant response of to infection, with phenylpyruvate being an important metabolite in the phenylpropanoid metabolic pathway. Additionally, the observed upregulation of α-linolenic acid and JA synthesis suggests potential activation of JA-dependent induced systemic resistance (ISR) against , possibly mediated through downstream MYC transcription factors. These findings indicate that JA signaling contributes significantly to defense response against fungal infection. Our findings provide foundational insights that may support the development of disease-resistant cultivars or biostimulant strategies for and related medicinal plants.