CONICET | Buscador de Institutos y Recursos Humanos

Abstract Aim: To investigate the cellular damage on Penicillium digitatum produced by a sequential oxidative treatment (SOT), previously standardized in our laboratory, to prevent the conidia growth. Lethal SOT consists of 2 min preincubation with 10 ppm NaClO followed by 2 min incubation with 6 mmol l-1 CuSO4 and 100 mmol l-1 H2O2 at 25ºC. Methods and Results: After the application of lethal SOT or sub-lethal SOT (decreasing only the H2O2 concentration), we analyzed several conidia features such as germination, oxygen consumption, ultrastructure, and integrity of the cellular wall and membrane. Also, we measured the production of reactive oxygen species (ROS) and the content of thiobarbituric acid-reactive species (TBARS). With the increase of H2O2 concentration in the SOT, germination and oxygen consumption of conidia became inhibited, while the membrane permeability, ROS production and TBARS content of conidia increased. Several studies revealed ultrastructural disorganization in P. digitatum conidia after lethal SOT, showing severe cellular damage without apparent damage to the cell wall. In addition, mycelium of P. digitatum was more sensitive than conidia to the oxidative treatment, since growth ceased and permeability of the membranes increased after exposure of the mycelium to a SOT with only 50 mmol l-1 H2O2 compared to a SOT of 100 mmol l-1 for these effects to occur on conidia. Conclusion: Our insights into cellular changes produced by the lethal SOT are consistent with mode of action of the oxidant compounds, by producing both alteration of membrane integrity and intracellular damage. Significance and Impact of the Study: Our results allow the understanding of SOT effects on P. digitatum, which will be useful to develop a reliable treatment to control postharvest diseases in view of its future application in packinghouses.