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

Abstract:

[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.