Phenolic compounds in enhancing physical barrier and suppressing growth of Ganoderma boninense PER71
Oil palm (OP) is one of the dominant plantation crops that bring so much abundance to many countries in terms of economic value, quality goods, and food products. However, the production of oil palm is hindered to a great extent, facing a devastating issue which started to decline in the cultivat...
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| Format: | Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/103919/1/DAARSHINI%20AP%20GANAPATHY%20-%20IR.pdf |
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| Summary: | Oil palm (OP) is one of the dominant plantation crops that bring so much
abundance to many countries in terms of economic value, quality goods, and
food products. However, the production of oil palm is hindered to a great extent,
facing a devastating issue which started to decline in the cultivation of palm oil
caused by basal stem rot (BSR) disease. Ganoderma boninense is the whiterot
basidiomycetes, the primary causal pathogen of BSR. This pathogen
invades via roots and degrades the lignin and cellulose components. Many
approaches are available in controlling BSR, although, there is no effective
method to suppress G. boninense completely. An alternative way to control
the disease is to safeguard the physical barriersand inhibit the production of
ligninolytic and hydrolytic enzymes by pathogen. Gallic acid (GA), thymol (THY),
propolis (PRO), and carvacrol (CARV) were used to study the effects of
phenolic compounds on the growth of G. boninense PER71, as well as to
determine how well they may suppress the development of ligninolytic and
hydrolytic enzymes. These four phenolic compounds with different
concentrations were able to inhibit the growth of G. boninense PER 71 at
different levels. Based on the study, mycelia grown on media containing the
phenolic compounds showed greater inhibition at the highest concentration
(GA 8 mg/ml, THY 0.25 mg/ml). Significant differences (p<0.05) were observed
and 94% inhibition was exerted by GA. The mycelial morphology under
scanningelectron microscopy (SEM) and high-resolution transmission electron
microscopy (HR-TEM) revealed that phenolic compounds have a greater
impact on mycelial structure, cell wall and cell membrane. The fungal
membrane integrity and permeability tested with a flow cytometer exerted
severe damage to the mycelium treated with GA and THY and reported the
highest amount of sugar (monosaccharides-glucose) and electrolyte leakage.
The ergosterol content present in the G. boninense PER71 was very much
interrelated with the morphological disruptions. Furthermore, to justify the
findings, suppression of hydrolytic and ligninolytic enzymes secreted by G.
boninense PER71 with the application of phenolic compounds were determined.
The phenolic compounds had shown inhibitory effects and a significant (p<0.05)
decrease in the secretion of enzymes. Among the phenolic compounds tested,
GA was the most effective compound in suppressing the hydrolytic and
ligninolytic enzymes followed by THY. The PRO and CARV had some
suppression on these enzymes but were not as effective as the other two.
The antifungal efficacyof the phenolic compounds during the studies indicated
the consistency in eliminating the G. boninense PER71. Moreover, the effectual
mode of delivery of the phenolic compound (encapsulation of beads) and
characterization were performedto validate the structure, quality and release of
the phenolic compound via SEM and High Performance Liquid
Chromatography (HPLC). The freshly encapsulated beads showed >90% of
inhibitory effect on G. boninense PER71. This study proposed that GA and
THY could be developed further as naturally occurring phenolic compounds
and deliver new strategies to eradicate the G. boninense and finally could be
used to control the BSR disease. |
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