Tan Xiaoli,Jiang Xiaobing,Chen Xiumei,Reymick Okwong Oketch,Zhu Chen,Tao Nengguo
Neofusicoccum parvum is one of the most hazardous pathogens causing mango fruit decay. The present study utilized trans -2-hexenal (TH), a typical antifungal component of plant essential oils (EOs), to control N. parvum both in vivo and in vitro, and attempted to explore the mechanisms involved. The findings showed that at concentrations greater than 0.4 µL/mL, TH exhibited exceptional antifungal activity against N. parvum in vitro. TH application led to the disruption of the structural integrity of both cell walls and cell membranes, with a particular impact on the latter, as evidenced by the dramatically increased propidium iodide level, as well as reduced total lipids and ergosterol content. Further DCFH-DA staining experiments showed that TH induced mycelial reactive oxygen species (ROS) accumulation, which exacerbated cell membrane lipid peroxidation. For easier application of TH, we fabricated aerogel-loaded TH (ALTH) materials, which demonstrated excellent antifungal activity in vitro. Infestation studies on fruits demonstrated that ALTH mitigated mango stem-end rot in a dose-dependent fashion, with a concentration of 40 µL/L showing efficacy comparable to the conventional fungicide prochloraz, while maintaining fruit quality. In light of these results, TH works by inducing ROS buildup and oxidative damage to the cell membrane of N. parvum , and is a particularly promising preservative for preventing postharvest infections in mangoes.
Rosa roxburghii Tratt., a vitamin C-rich edible and medicinal fruit native to southwest China, plays a vital role in poverty alleviation and economic development in mountainous regions. In this study, Neofusicoccum parvum was identified for the first time as a pathogen causing fruit rot in R. roxburghii . Koch's postulates were fulfilled by re-isolating the fungus from artificially inoculated fruits, confirming its pathogenicity. Morphological and molecular analyses further validated the pathogen's identity. The optimal growth conditions for N. parvum were determined to be 28–30 °C and pH 5, with D-fructose and NH 4 Cl as the preferred carbon and nitrogen sources, respectively. Continuous light exposure was found to maximize mycelial growth. Among six tested plant extracts, osthol, Scutellariae Radix extract, and matrine exhibited notable antifungal activity, with osthol showing the highest efficacy (EC 50 = 30.57 μg/mL). Field trials demonstrated that 1% osthol emulsion in water (EW), applied at 300–500-fold dilution, achieved 60.68%–77.57% control efficacy against fruit rot after 21 d of the second application. This performance was comparable to the chemical fungicide 10% difenoconazole water dispersible granule (WG) (67.58%–81.04% efficacy at 5000–7000-fold dilution). This study provides a scientific basis for the biocontrol of N. parvum -induced fruit rot disease in R. roxburghii .
Xiaoli Tan,Xiaobing Jiang,Okwong Oketch Reymick,Chen Zhu,Nengguo Tao
Stem-end rot caused by Neofusicoccum parvum is among the most detrimental diseases affecting postharvest mangoes. The present investigation utilized ( E )-2-octenal to manage N. parvum infections, elucidating its mechanism of action. The findings revealed that ( E )-2-octenal exhibited outstanding antimicrobial potency against N. parvum in vitro within the concentration range of 0.4–1.6 µL/mL. Additionally, ( E )-2-octenal significantly compromised the cell membrane integrity and mitochondrial energy metabolism of N. parvum , evidenced by dramatically increased intracellular material leakage and ROS levels, along with reduced mitochondrial membrane potential, ATP, and energy charge. Further experiments showed noteworthy effects on the tricarboxylic acid cycle (TCA) cycle and the key enzyme activities of succinate dehydrogenase (SDH) and malate dehydrogenase (MDH). Molecular docking revealed hydrogen bonding between ( E )-2-octenal’s aldehyde group and SDH (Trp-307) and MDH (Gly-101), indicating direct targeting of these enzymes for inhibition. To enhance the practical application of ( E )-2-octenal, we developed an aerogel-loaded ( E )-2-octenal material (ALO) that exhibited superior antimicrobial efficacy in vitro . In vivo , ALO effectively controlled mango stem-end rot, with optimal efficacy at 20 µL/L. This concentration also delayed the natural disease of mango without degrading fruit quality. According to these findings, ( E )-2-octenal is a promising preservative against postharvest mango infections, potentially by impeding cellular energy metabolism through direct interaction with SDH and MDH within the TCA pathway, culminating in mitochondrial dysfunction and cell membrane damage.
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