Transcriptomics analysis elucidates the growth inhibitory mechanisms of volatile fungistatic compound 3-ethylbenzaldehyde to Pseudocryphonectria elaeocarpicola.

Pseudocryphonectria elaeocarpicola is a highly destructive plant pathogenic fungus that causes Elaeocarpus stem blight, leading to significant economic losses and ecological damage in urban greening systems. Previous work showed that the volatile organic compound (VOC) 3-ethylbenzaldehyde exhibits significant inhibitory effects against P. elaeocarpicola. Treatment with an exceptionally low concentration of 3-ethylbenzaldehyde (3.724 μg/mL) resulted in a 100% inhibition rate of mycelial growth. To elucidate the antifungal mechanism of this VOC, we conducted a comparative transcriptomic analysis of P. elaeocarpicola treated with 1× (0.931 μg/mL) and 2× (1.862 μg/mL) concentrations of 3-ethylbenzaldehyde. Results demonstrated that 3-ethylbenzaldehyde exhibits typical concentration dependent antifungal activity. Functional enrichment analysis demonstrated that central carbon metabolic pathways, such as starch and sucrose metabolism and glycolysis/gluconeogenesis, play a central role in the mechanism of action of this compound. The DNA replication pathway exhibits a unique concentration-response pattern and plays a critical role in the defense of P. elaeocarpicola against 3-ethylbenzaldehyde. Among them, five key regulatory genes involved in the mentioned above processes were selected as the potential target of 3-ethylbenzaldehyde and validated to be involved in fungal growth by exogenous application of dsRNA. This study reported the molecular mechanism underlying the antifungal action of 3-ethylbenzaldehyde, which inhibited the growth of P. elaeocarpicola by suppressing multiple pathways, including central carbon metabolism and DNA replication, demonstrating significant potential for application in the development of novel and highly effective agents against Elaeocarpus stem blight.