Preliminary study on the effects of fusaric acid treated protocorm-like bodies of Dendrobium hybrid against Fusarium proliferatum and Fusarium oxysporum

Aims: Dendrobiums are majorly affected by Fusarium proliferatum and F. oxysporum.The aim of this research was to utilise the mycotoxin, fusaric acid (FA) on Dendrobium hybrid to produce cultivars that are resistant towards these fungi.Methodology and results: FA of concentrations 0.05, 0.10, 0.15 and 0.20 mM were transferred to sterilised halfstrength Murashige and Skoog (MS) medium and inoculated with four weeks old thin cell layer (TCL) of protocorm-like bodies (PLBs) for eight weeks.It was deduced that PLBs treated with 0.10 mM of FA resulted in highest survival and shoot regeneration rate but the survival and regeneration rate began to decline as the concentrations of FA were increased.Histology and scanning electron microscopy (SEM) observation showed prominent cell damage and stomatal closure in PLBs treated with FA.Direct amplification of minisatellite DNA (DAMD) markers showed polymorphism in the FA treated PLBs compared to the control PLBs.In the leaf bridge bioassay, plantlets treated with 0.05 mM of FA showed most resistance towards both fungal species.Conclusion, significance and impact of study: Therefore, this research is a preliminary screening study where the optimum concentration of FA was selected based on the reaction of treated TCL of PLBs towards these mutagens.