余甘子采后软腐病菌的分离鉴定及其细胞壁水解酶活性

Identification of the pathogen causing fruit rot of postharvest Phyllanthus emblica and its cell wall degrading enzyme activity

【背景】药食同源的余甘子果实在采后贮藏过程中极易软腐变质,严重影响其品质和经济价值。【目的】明确引起余甘子果实软腐病的病原菌种类及其生长特性和产细胞壁水解酶活性,为余甘子采后软腐病的控制及延长其贮藏期奠定基础。【方法】采用组织块分离法从采后发病的余甘子果实分离病原菌,按照科赫法则确定分离菌株的致病性;采用形态学特征结合rDNA-ITS序列分析对病原菌进行鉴定,测定病原菌菌丝生长和产孢特性,检测产胞外细胞壁水解酶活性。【结果】从具有软腐症状的余甘子果实中分离得到32株真菌,其中菌株DQ23是余甘子采后软腐病的致病菌,通过形态特征结合rDNA-ITS序列将其鉴定为Penicillium choerospondiatis。其菌丝在酵母膏葡萄糖琼脂培养基(YDA)上生长最快,在马铃薯蔗糖琼脂培养基(PSA)上产孢最多。该菌能有效利用多种碳、氮源,适宜产孢的碳源为蔗糖、葡萄糖,氮源为蛋白胨、牛肉膏、酵母膏。菌丝生长的最适温度和pH范围分别为25°C和3.0-5.0,产孢的最适温度和pH范围分别为25°C和4.0-7.0。光照均利于菌丝生长和产孢。该菌具有分解果胶、纤维素的能力,无分解蛋白质、鞣质的能力。【结论】Penicillium choerospondiatis是余甘子果实软腐病的病原菌,研究结果为该病害的防控奠定了基础。

[Background]In the process of postharvest,Phyllanthus emblica both as diet and medicine is easy to be perishable,which can seriously decrease its quality and economic value.[Objective]We identified the pathogen causing fruit rot of postharvest Phyllanthus emblica,its biological characteristics and cell wall degrading enzyme activity analysis,in order to provide the basis for rot disease control and extension of the storage life of Phylanthus emblica fruit.[Methods]The pathogen isolated from fruit rot of postharvest Phyllanthus emblica by tissue isolation method,followed by Koch’s postulates pathogenicity test.The pathogen was identified based on morphological characteristics and rDNA-ITS sequence analysis.In addition,the pathogenic mycelia growth and spore characteristics were determined,the activity of extracellular cell wall degrading enzyme activity were also detected.[Results]Thirty-two fungi isolates were isolated from the fruit rot of Phyllanthus emblica.Strain DQ23 was the causal pathogen fungus of fruit rot of postharvest Phyllanthus emblica.The pathogen strain DQ23 was identified as Penicillium choerospondiatis via morphological characteristics and rDNA-ITS sequence analysis.YDA medium was the most appropriate for mycelium growth.PSA was the optimum medium for conidia production.The mycelium could utilize a variety of carbon and nitrogen sources.For conidia production,the optimum carbon sources were sucrose and glucose,and the optimum nitrogen source were tryptone,beef extract and yeast extract.The best mycelium growth was obtained at 25°C and pH 3.0-5.0.The conidia production increased rapidly at 25°C and pH 4.0-7.0.Continuous light was beneficial to mycelial growth and spore production.Penicillium choerospondiatis could decompose pectin and cellulose,but not protein and tannin.[Conclusion]Penicillium choerospondiatis strain DQ23 was the pathogenic fungi causing fruit rot of Phyllanthus emblica,and possessed higher pectinase and cellulase activity.