Suppression of lignohemicellulosic degradation caused by Ganoderma boninense in oil palm during basal stem rot establishment using benzoic acid
The palm oil industry is one of the most successful industries in the world in terms of agricultural crops towards economic growth and development in its producing countries. Indonesia and Malaysia have become the main producers of palm oil dominated approximately 85% of the total world productio...
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| Format: | Thesis |
| Language: | English |
| Published: |
2022
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/103920/1/ROZI%20FERNANDA%20-%20IR.pdf |
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| Summary: | The palm oil industry is one of the most successful industries in the world in
terms of agricultural crops towards economic growth and development in its
producing countries. Indonesia and Malaysia have become the main producers
of palm oil dominated approximately 85% of the total world production of palm
oil. However, a decline in the production of this oil has been observed that
occurred due to the presence of white-rot fungus Ganoderma boninense the
causal pathogen of basal stem rot (BSR) disease causing the degradation in the
lower part of the trunk. G. boninense degrades the major components of wood in
the lower trunk makes a loss of its support to the palm, which eventually caused
the palm to collapse. Inefficacy in controlling this disease could be the lack of
understanding of how the pathogen establishes itself in the host and degrade the
structural components of oil palm trees. One of the potential compounds that can
be used to suppress the growth of G. boninense is benzoic acid (BA). BA belong
to aromatic carboxylic acid group that has antifungal effect against many
pathogenic fungi. Therefore, this study aimed to understand a step-by-step
mechanism of structural degradation of oil palm by G. boninense and the effect
of BA on suppression of G. boninense growth and enzymatic activities while
maintaining the structural components of oil palm wood (OPW). The antifungal
activity of BA at different concentrations against the growth and enzymatic
activities of G. boninense were tested using OPW as the substrate. Further, the
use of BA to strengthen the lignin structure in oil palm seedlings was evaluated.
BA at a concentration above 5 mM successfully inhibited the growth of G.
boninense in in-vitro study. The mechanism of pathogen suppression by BA was
related to the disruption and depolarization of fungal cell membrane lead to the
loss in membrane permeability and integrity and finally caused the alteration in
morphological, anatomical, and ultracellular structure of fungal mycelia. The
study on wood degradation by G. boninense in response to BA treatment
showed that G. boninense simultaneously degrade all the components of OPW.
A significant (P < 0.05) reduction in wood weight loss and wood chemical
component was observed in the BA-treated woodblock at 5mM and above. BA
significantly reduced the degradation of OPW depending on its concentration.
Microscopic observation of wood inoculated with G. boninense showed that the
severe damage in wood structure of untreated wood block in compare with
treated wood block showing least damage in the wood structure. This was due to
the suppression of the ligno-hemicellulolytic activity of G. boninense by BA. The
observation at the nursery level showed that during the disease establishment,
G. boninense colonized the plant's root tissue 10 to 14 days after inoculation,
while BA-treated seedlings showed the slow disease progression that colonized
the root tissues in 7 to 8 weeks after inoculation. BA affect the morphological,
anatomical, and cellular structure of G. boninense unable them to produce
lignohemicellulolytic enzymes for degradation of wood lignohemicellulose. In
addition, BA induced the activity of defense-related enzymes that increase lignin
biosynthesis in the oil palm seedlings. These findings could be useful in
understanding the mechanism of G. boninense infection in OPW and contribute
to the development of sustainable control of BSR disease. |
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