Effects of stilbenoids on growth, mycotoxin production and transcriptomic profiles of Aspergillus carbonarius causing postharvest black spot disease.

Black spot caused by Aspergillus carbonarius not only reduces fruit quality but also leads to mycotoxin accumulation, resulting in substantial economic losses to the global fruit industry. In the present study, we evaluated the potential of natural polyphenolic stilbenoids as inhibitors against A. carbonarius. In vitro tests showed that stilbenoid treatments suppressed the growth, development, and mycotoxin production of A. carbonarius. Among them, pterostilbene (PT) exhibited stronger efficacy than resveratrol (RE) and piceatannol (PI), delaying the stages of spore germination and mycelial growth by 40-64 h and achieving a 93.43% inhibition rate of ochratoxin A (OTA). Further investigations revealed that stilbenoids disrupted the microstructural integrity of mycelia, leading to the leakage of intracellular ions and proteins, reducing malondialdehyde (MDA) and reactive oxygen species (ROS) levels, and upregulating antioxidant-related genes such as SOD, POD, GR, and CAT. Given PT's superior performance, transcriptomic analysis conducted, revealed that PT treatment induced abnormal expression of genes involved in ribosomal translation, membrane components and transport, lipid metabolism, antioxidant enzymes, and secondary metabolism pathways in A. carbonarius. These inhibited its growth and toxin production. Further in-depth analysis identified 5 metabolic regulatory transcription factors and 10 hub transcription factors involved in the regulation. Among them, AcYHP1 exerted dual functions, and the target genes of AcCREA and AcMCM1 were mainly annotated in key processes such as lipid metabolism, antioxidant system, and OTA biosynthesis. These findings indicate that stilbenoids hold promise as novel green fungicides, providing an environmentally friendly strategy for controlling postharvest black spot disease.