ABSTRACT
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 half-strength 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.
ABSTRACT
@#Aims:The ever-revolving fungi strains and environmental and health concerns due to current practice of synthetic pesticide in agricultural fields have encourages more ventures into bio-pesticides research. Mimusops elengi, a widely available endogenous plant intropical countries and most parts of this plant have been proven to possess medicinal and antimicrobial potential. In this study, M.elengiseeds crude extracts are tested for their antifungal activities on paddy seed-borne and pathogenic fungi.Methodology and results:The dried and grinded M.elengiseeds are macerated separately using water, methanol, ethyl acetate, dichloromethane and petroleum ether as extraction medium. Crude extract of each solvent wasused on paddy seed surface treatment to determine their antifungal inhibition potential on seed-borne fungi and paddy grain germination. Synthetic fungicide mancozeb and thiram are also tested as comparisons to the performance of plant extracts. Water andmethanol extracts exerted the best fungal inhibiting and grain germination results from the five crude extracts tested and qualitative phytochemical screening reveals both extracts contained the most number of phytoconstituents including saponin, flavonoids, alkaloids, tannins and phenolic. Water extract, methanol extracts and synthetic fungicides are then subjected to in-vitro bioassay to observe their effect on mycelial growth of several fungi strains pathogenic to paddy namely, Fusarium fujikuroi,Curvularia aeria,C.lunata andC.eragrostidis.Water and methanol extracts showed a very similar trend of inhibition on all four fungi strains tested with best percentage of inhibition on mycelia growth of C.eragrostidisfollowed by C. aeria, C. lunataand least effective on F.fujikuroi. Further separation of crude extract need to be done to isolate the specific acting compounds contributing to fungal growth inhibition.Conclusion, significance and impact of study:Both water and methanol extracts of the seeds contain promising antifungal properties on seed borne fungi which is as good as the synthetic fungicides compared in this study. A broad range of active phytochemical properties it possesses may be the contributing factor for the fungal growth inhibition. This preliminary screening could narrow down the potential of this seed extracts as natural antifungal agents and the acting active compounds.
ABSTRACT
Objective To test the effectiveness of conidial spore formulations [Aspergillus tubingensis (A. tubingensis) and Trichoderma harzianum (T. harzianum)] against tropical bed bugs, Cimex hemipterus. Methods Spore formulations were made from two fungal strains, T. harzianum and A. tubingensis. The bed bugs were exposed to the conidial spores placed soaked onto a fabric cloth for 1 h and the mortality counts were recorded daily until 14 days. Results Mean survival times based on Kaplan–Meier survival analysis showed no significant differences between all the concentrations in both the fungal isolates: T. harzianum and A. tubingensis. However, the evaluation of both the isolates in terms of virulence resulted in low lethal hours in all the concentrations except for the high concentration of A. tubingensis (LT