为明确反,反-2,4-壬二烯醛(trans, trans-2,4-nonadienal,E24 N)对枇杷采后优势致病菌尖孢炭疽菌(Colletotrichum acutatum)的控制效果及机制,采用不同浓度E24 N处理尖孢炭疽菌,通过生理生化分析及微观结构观察研究其对尖孢炭疽菌的影响。结果表明,通过琼脂稀释法测得E24 N对尖孢炭疽菌的最小抑菌浓度和最小杀菌浓度均为0.4 mL/L。0.05 mL/L E24 N溶液处理尖孢炭疽菌12 h后孢子萌发率仅为(7.01±1.98)%,显著低于对照组孢子萌发率(85.41±4.75)%(P＜0.05)。采用扫描电子显微镜和透射电子显微镜观察发现,E24 N处理破坏了尖孢炭疽菌的菌丝形态,细胞完整性受损,细胞器结构无法辨认。此外,E24 N处理改变了尖孢炭疽菌细胞通透性,导致其蛋白质和核酸外泄,相对电导率升高,膜脂质过氧化反应增强,活性氧积累。果实实验结果表明,采用E24 N处理可以延缓枇杷果实炭疽病的发病进程,其抑制效果显著优于同为脂肪醛类的天然保鲜剂柠檬醛。综上,E24 N通过抑制尖孢炭疽菌孢子萌发和菌丝生长,破坏其细胞结构,促进脂质过氧化和活性氧积累,从而影响其正常生理功能,延缓枇杷果实炭疽病的发生,为脂肪醛类化合物在枇杷炭疽病防治中的应用提供了新的理论依据。
This study aimed to clarify the antibacterial effect and mechanism of trans, trans-2,4-nonadienal (E24 N) on Colletotrichum acutatum, the dominant postharvest pathogen of loquat.The effects of different concentrations of E24 N on C.acutatum were investigated by physicochemical analysis and microstructural observation.Results showed that the minimum inhibitory concentration and minimum bactericidal concentration of E24 N against C.acutatum determined by the agar dilution method were both 0.4 mL/L.The germination of spores treated with 0.05 mL/L E24 N solution for 12 hours was only (7.01±1.98)%, significantly lower than the control group spore germination rate of (85.41±4.75)% (P<0.05).Observations of morphological changes in C.acutatum using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that treatment with E24 N disrupted the fungal hyphae, destroyed the integrity of the cells, and rendered the organelle structures unrecognizable.Additionally, treatment with E24 N altered the cell permeability of C.acutatum, leading to the leakage of proteins and nucleic acids, an increase in relative conductivity, enhanced lipid peroxidation in the membrane, and accumulation of reactive oxygen species.The results of the fruit experiment indicated that treating loquat fruits with E24 N could delay the progression of anthracnose in loquat fruits, with an inhibitory effect superior to that of citral, a commonly used aliphatic aldehyde preservative in production.In conclusion, E24 N inhibited the germination of C.acutatum spores and mycelial growth, disrupted its cellular structure, and promoted lipid peroxidation and the accumulation of reactive oxygen species, thereby affecting its normal physiological functions and suppressing the occurrence of anthracnose on loquat fruits.This study provides new theoretical evidence for the application of aliphatic aldehyde compounds in the prevention and control of anthracnose in loquats.
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