Fusarium oxysporum is an ascomycete facultative fungus which generally affects to plants. However, it is recently known as a serious emerging opportunistic pathogen of human and other animals. F. oxysporum shows broad resistance to commonly used antifungal agents and therefore development of alternative therapeutic agents is required. In this study, we investigated the antifungal efficacy of plant based natural lawsone against pathogenic F. oxysporum. Antifungal susceptibility test determined the concentration dependent growth inhibition of lawsone against F. oxysporum with minimum inhibitory concentration (MIC) at 100μg/mL. Ultra-structural analysis indicates the prominent damage on cell wall of the mycelium after lawsone treatment, and suggests that it could increase the membrane permeability and disintegration of cells leading to cellular death. Propidium iodide (PI) uptake assay results showed the higher level of cell death in lawsone treated F. oxysporum which further confirms the loss of plasma membrane integrity. Also, detection of reactive oxygen species (ROS) using DCFH-DA has clearly indicated that lawsone (100μg/mL) can induce the ROS level in the filaments of F. oxysporum. MTT assay results showed the loss of viability and germination capacity of F. oxysporum spores by lawsone in concentration dependent manner. Moreover, lawsone treatment induced the mRNA expression of two autophagy related genes (ATG1 and ATG8) indicating that lawsone may activate the autophagy related pathways in F. oxysporum due to the oxidative stress generated by ROS. F. oxysporum infected zebrafish has recovered after lawsone therapy as a topical treatment suggesting that lawsone is a potential natural antifusariosis agent.

Abstract:The ability of in vitro micropropagtion to produce high quality planting material in large quantities is hindered by their high cost of production. Hence the price of planting material is high, making them unaffordable to growers. However, a larger portion of the capital and running cost of micropropagation can be reduced using CSUP (pronounced as seesap) technique, where sodium hypochlorite is used to sterilize glassware and culture media followed by culturing without using a laminar flow cabinet. This study was undertaken with the objective of evaluating the feasibility of the CSUP technique to replace the sterilization carried out using autoclaves and laminar flow cabinets.Sodium hypochlorite in four concentrations 5, 10, 15 and 20% (v/v) were used to rinse glassware and accessories prior to pouring the appropriate culture medium for anthurium cv 'Tropical Red' in vitro shoot multiplication. The culturing of axenic shoots was carried out inside a glass-cage and cultures were placed in the growth room. Autoclaved culture medium and a laminar flow cabinet were used in the case of the control cultures. Results revealed that the percentage of contaminationfree cultures, dry weight increase and the shoot multiplication were not significantly different between the respective treatments and the controls, as well as among treatments of different sodium hypochlorite concentrations. Therefore, the CSUP technique using 5% (v/v) sodium hypochlorite solution can be adopted to replace the use of an autoclave and the laminar flow cabinet in the major micropropagation activity of in vitro multiplication.

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Development of nanostructured films using natural polymers and metals has become a considerable interest in various biomedical applications. Objective of the present study was to develop silver nano particles (AgNPs) embedded chitosan films with antimicrobial properties. Based on the Ag content, two types of chitosan silver nano films, named as CAgNfs-12 (12 mM) and CAgNfs-52 (52 mM) were prepared and characterized. Field emission scanning electron microscope (FE-SEM) images of two CAgNfs showed the circular AgNPs, which were uniformly embedded and distributed in the matrix of chitosan films. Antimicrobial experiment results clearly indicated that CAgNfs can inhibit the growth of fish pathogenic bacteria Vibrio (Allivibrio) salmonicida, V. tapetis, Edwardsiella tarda and fungi Fusarium oxysporum. Moreover, CAgNfs significantly reduced the experimentally exposed V. salmonicida levels in artificial seawater, suggesting that these CAgNfs could be used to develop antimicrobial filters/membranes for water purifying units to eliminate the pathogenic microbes.