6-Pentyl-2H-pyran-2-one from Trichoderma erinaceum Is Fungicidal against Litchi Downy Blight Pathogen Peronophythora litchii and Preservation of Litchi

2-Heptanol inhibits Botrytis cinerea by accelerating amino acid metabolism and retarding membrane transport

During the postharvest storage of tomatoes, they are susceptible to infection by Botrytis cinerea, leading to significant economic losses. This study evaluated the antifungal potential of 2-heptanol (2-HE), a volatile biogenic compound, against B. cinerea and explored the underlying antifungal mechanism. The results indicated that 2-HE effectively suppressed the growth of B. cinerea mycelia both in vivo and in vitro and stimulated the activities of antioxidative enzymes, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in tomatoes. Furthermore, 2-HE reduced spore viability, compromised membrane integrity, and resulted in increased levels of extracellular nucleic acids, protein content, and membrane lipid peroxidation. Transcriptomic analysis revealed that 2-HE disrupted the membrane transport system and enhanced amino acid metabolism, which led to intracellular nutrient depletion and subsequent B. cinerea cell death. Additionally, the 2-HE treatment did not negatively impact the appearance or quality of the tomatoes. In conclusion, the findings of this study offer insights into the use of 2-HE as a biocontrol agent in food and agricultural applications.

Effectiveness of Volatiles Emitted by Streptomyces abikoensis TJGA-19 for Managing Litchi Downy Blight Disease

Litchi is a fruit of significant commercial value; however, its quality and yield are hindered by downy blight disease caused by Peronophythora litchii. In this study, volatile organic compounds (VOCs) from Streptomyces abikoensis TJGA-19 were investigated for their antifungal effects and studied in vitro and in planta for the suppression of litchi downy blight disease in litchi leaves and fruits. The growth of P. litchii was inhibited by VOCs produced by TJGA-19 cultivated on autoclaved wheat seeds for durations of 10, 20, or 30 days. Volatiles from 20-day-old cultures were more active in inhibition effect against P. litchii than those from 10- or 30-day-old cultures. These volatiles inhibit the growth of mycelia, sporulation, and oospore production, without any significant effect on sporangia germination. Additionally, the VOCs were effective in suppressing disease severity in detached litchi leaf and fruit infection assays. With the increase in the weight of the wheat seed culture of S.abikoensis TJGA-19, the diameters of disease spots on leaves, as well as the incidence rate and disease indices on fruits, decreased significantly. Microscopic results from SEM and TEM investigations showed abnormal morphology of sporangia, mycelia, and sporangiophores, as well as organelle damage in P. litchii caused by VOCs of TJGA-19. Spectroscopic analysis revealed the identification of 22 VOCs produced by TJGA-19, among which the most dominant compound was 2-Methyliborneol. These findings indicated the significant role of TJGA-19 compounds in the control of litchi downy blight disease and in improving fruit quality.