吡啶-2,6-二羧酸处理对梨果采后黑斑病控制作用及其抑菌机理

Control Effect of Pyridine-2,6-Dipicolinic Acid Treatment on Postharvest Black Spot of Pear Fruit and Possible Antifungal Mechanism

由互隔交链孢(Alternaria alternata)引起的黑斑病是梨果主要采后病害之一,会导致严重的经济损失。本实验以梨果黑斑病菌A.alternata为研究对象,通过体内外实验研究了枯草芽孢杆菌(Bacillus subtilis)代谢产物吡啶-2,6-二羧酸(pyridine-2,6-dipicolinic acid,DPA)对A.alternata生长的抑制和对梨果黑斑病的控制作用,并进一步探讨了其抑菌作用的机理。结果表明:DPA能显著抑制A.alternata的菌落生长、孢子萌发以及芽管伸长,其中2.0 mmol/L DPA处理后培养9 d时A.alternata菌落直径仅为对照组的51.76%,4.0 mmol/L处理可完全抑制A.alternata的生长。DPA处理对梨果黑斑病的扩展有明显的控制作用,贮存至第11天时,20.0 mmol/L DPA处理组早酥梨病斑直径仅为对照组的55.17%。进一步研究表明,DPA处理提高了A.alternata细胞膜的通透性,菌丝电导率、蛋白质和核酸渗漏量显著增加,同时DPA处理降低了细胞膜组分麦角甾醇质量浓度,提高了A.alternata丙二醛浓度。结论:DPA可通过延缓A.alternata生长、提高膜通透性、破坏细胞膜的完整性和促使膜脂氧化而发挥抑菌作用。

Black spot,caused by Alternaria alternata,is one of the major postharvest diseases of pear fruit,which can cause severe economic losses.The inhibitory effect of pyridine-2,6-dipicolinic acid(DPA)produced by Bacillus subtilis on the growth of A.alternata and black spot development was studied through in vitro and in vivo tests,and its possible mechanism of action was also evaluated.Results showed that DPA significantly inhibited the colony growth,spore germination and germ tube elongation of A.alternata.The colony diameter of A.alternata treated with 2.0 mmol/L DPA was only 51.76%as compared to the control group after incubation for nine days,and A.alternata growth was completely inhibited by 4.0 mmol/L DPA treatment.DPA treatment had a significant control effect on the development of black spot on pear fruit.The lesion diameter on Zaosu pear fruit treated with 20.0 mmol/L DPA was only 55.17%as compared to the control after 11 days of storage.Furthermore,it was shown that DPA treatment significantly increased the cell membrane permeability and mycelial conductivity of A.alternata,leading to protein and nucleic acid leakage.At the same time,DPA treatment reduced the ergosterol content and increased the malondialdehyde content of A.alternata.The above results indicate that DPA has strong antifungal activity through delaying A.altenata growth,destroying membrane integrity,increasing membrane permeability and promoting membrane lipid oxidation.