Khim Phin Chong

First identification of ganoderma boninense isolated from Sabah based on PCR and sequence homology

Basal stem rot (BSR) of oil palm ( Elaeis guineensis ) is caused by Ganoderma boninense , and, commercially, is one of the most devastating diseases in South East Asia. Losses of more than 80% of stands by the time they are halfway through their normal economic life have been reported. High incidence of BSR results in economic losses due to zero yields from dead palms and significantly reduced weight and number of fruit bunches in infected but living palms. Due to the importance of oil palm industry to Malaysia’s economy, the transfer of any materials that are related to Ganoderma is strictly prohibited from Peninsular Malaysia to Sabah and Sarawak. No basic identification method using molecular techniques for the identification of G. boninense exist in this study for G. boninense isolates from Sabah. The only report on this pathogens isolate in Sabah was based on their morphology and pathogencity. In conjunction with the morphological similarities among the different isolates, there are numerous opinions on the aggressiveness of the pathogen in Sabah. The isolates of G. boninense from Sabah were claimed to be less aggressive compared to those from Peninsular Malaysia. This may be due to lower incidence of BSR in Sabah and Sarawak compared to Peninsular Malaysia. Since the oil palm industry is a fast income-generating tool, data related to it may be highly sensitive. Researchers, plantation managers and entrepreneurs are not forthcoming with the information on oil palm genetic materials or isolates of G. boninense with others. The current speculations on the Sabah isolates need further investigation. In this study, we report the identity of isolates Ganoderma from Langkon Oil Palm Estate in Sabah, Malaysia. The identity of these isolates was confirmed using DNA sequence analysis after PCR amplification. The latter method shows that the Sabah isolates were very similar to aggressive G. boninense strains FA5017 or FA5035 from West Malaysia, with a maximum similarity of 98%. Key words: Aggressive, FA5017, FA5035, G1_5, isolate.

In Vitro Antimicrobial Activity of Cynodon dactylon (L.) Pers. (bermuda) Against Selected Pathogens

Cynodon dactylon (L.) Pers. is a type of perennial grass that possesses great medicinal values. In this study, the antimicrobial activity of the plant crude extract from seven different solvents (acetone, chloroform, diethyl ether, ethanol, ethyl acetate, methanol, and n-pentane) was investigated against some pathogens (Bacillus cereus, Bacillus subtilis, Escherichia coli, Klebsiella spp., Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumonia) using disc diffusion method and thin-layer chromatographic (TLC) bioassay for plant-SPE extracts against Aspergillus niger. Crude extraction showed that ethanolic extraction produced highest yield (7.065 %) followed by methanolic (5.420 %) and chloroform (3.550 %) extraction. The lowest yield was obtained from n-pentane extraction (0.500 %). The antimicrobial study revealed broad spectrum of antimicrobial activity from ethanol (7.0–10.0 ± 0.0–1.0 mm) and ethyl acetate (7.0–12.0 ± 0.0–1.0 mm) extracts against all of the bacterial pathogens. Both methanol and acetone extracts showed activity to B. cereus (8.0 ± 0.0 mm) and B. subtilis (7.0 ± 0.0 mm), while chloroform extract showed activity to B. subtilis (7.0 ± 0.0 mm) and S.pyogenes (8.3 ± 0.6 mm), respectively. Diethyl ether extraction showed activity only to S. pyogenes (7.3 ± 0.6 mm), while no activity was observed from n-pentane extraction. Great antimicrobial activity were observed for both ethyl acetate and ethanol SPE-based extracts (SBE) with size of inhibition ranging from 8.0 ± 0.0 mm to 15.7 ± 0.6 mm for ethyl acetate SBE and 8.0 ± 0.0 mm to 13.0 ± 0.0 mm for ethanol SBE. No significant antimicrobial activity was observed from thin-layer chromatographic bioassay against A. niger.

Morphological changes of Ganoderma boninense mycelia after challenged by Trichoderma and Bacillus

Ganoderma boninense is a fungal pathogen that causes Basal Stem Rot (BSR) disease in oil palm. This deadly disease has caused major losses in the oil palm industry and no remedy is reported to date. The more promising control on G. boninense is the use of biological control agents (BCAs). Despite many attempts in using BCAs as a control agent but evidence on the colonization of BCAs and morphological changes of the pathogen is not well documented. We have investigated the effect of antagonist activity on the combination of Trichoderma spp. and Bacillus spp. on the morphology of G. boninense. The antagonist activity was evaluated using agar well diffusion assay. BCAs suppressed the mycelia growth of G. boninense up to 70%. Observation under Scanning Electron Microscopy (SEM) shows these BCAs induced stripping of G. boninense hyphal structure by destroying the cellular structure. Highly disrupted, disaggerated, shrivelled and lysis of G. boninense hyphal were also observed. The antifungal activity of Tricho...

Pathogenic Nature of Ganoderma boninense and Basal Stem Rot Disease

The oil palm industry is under threat of a prevailing incurable disease called Basal Root Stem (BSR), which is caused by a white rot fungi, known as Ganoderma boninense . With no current remedy at present, BSR is the major disease in oil palm plantations of SEA and, therefore, of great economic importance to the world oil palm industry, especially to Malaysia and Indonesia, which are oil palm major producers and exporters. The disease is highly associated with the decay of lower stem, leading to severe symptoms such as unopened and flattening spear leaves. There are numerous mode of infection associated with the epidemiology of G. boninense in oil palm plantation, including in-contact roots with nearby diseased palms and through airborne basidiospores . Deep insight on the route of infection and mycological pathogenicity behaviour of the pathogen is the greatest priority in order to successfully develop effective management practices for disease control.

Control Methods of G. boninense in Oil Palm Industry

Basal Stem Rot (BSR) is a very important disease to the oil palm industry. When it was first recorded, BSR only affected mature palms. However after years, the disease had progressed to affecting younger palms and causing more losses. The disease continues to inflict considerable yield losses of infected palms and also direct loss of stand due to palm death. Attempts to control the disease has been taken to wider extent, including cultural practices (clean clearing , windrowing , mounding, surgery, digging trenches, sanitation ), fungicide application, development of resistance variety and application of biological control agents . This chapter elaborates all possible managing strategies in combating Ganoderma boninense.

Current Detection Methods of G. boninense Infection in Oil Palm

Basal Stem Rot (BSR) disease has been spreading fast due to the inability to detect infection at the early stage in the field. The detection of the disease is challenging because the external symptoms are only visible when it is at the critical stage. During this stage, any treatment or management methods are no longer effective. Therefore, many viable and effective methods to detect the presence of G. boninense has been developed to diagnose the disease at early stage. This chapter elaborates established methods in detecting G. boninense including molecular analysis, biochemical assay, field detection methods using devices and some others emerging methods currently utilized.

Control of G. boninense Using Multi-biological Agents

Available control measures in managing Basal Stem Rot (BSR) disease has given unsatisfactory result. Alternative control measure to overcome this disease are now focused on the use of Biological Control Agents (BCAs) . Currently introduction of Multiple Biological Agents (Multi-BCAs) to expand their mode of action has been applied in managing plant pathogen. Selecting the right combination of antagonists is necessary not only to avoid competition among the BCAs but also complementing each other. In addition, a different ecological requirement of BCAs would broaden the range of environmental conditions and made the biological control more feasible. Most combinations are only involving two organisms, but few involved combinations of three or more organisms. In this chapter, the efficacy of microbes using combinations of microbes which are solely Multi-BCAs and Multi-BCAs with additive against Ganoderma boninense are discussed.

The potential of papaya leaf extract in controlling Ganoderma boninense

Basal Stem Rot (BSR) disease causes significant losses to the oil palm industry. Numerous controls have been applied in managing the disease but no conclusive result was reported. This study investigated the antifungal potential of papaya leaf extracts against Ganoderma boninense, the causal pathogen of BSR. Among the five different solvents tested in extraction of compounds from papaya leaf, methanol and acetone gave the highest yield. In vitro antifungal activity of the methanol and acetone extracts were evaluated against G. boninense using agar dilution at four concentrations: 5 mg mL-1, 15 mg mL-1, 30 mg mL-1and 45 mg mL-1. The results indicated a positive correlation between the concentration of leaf extracts and the inhibition of G. boninense. ED50 of methanol and acetone crude extracts were determined to be 32.016 mg mL-1and 65.268 mg mL-1, respectively. The extracts were later semi-purified using solid phase extraction (SPE) and the nine bioactive compounds were identified: decanoic acid, 2-methyl-, Z,Z-10-12-Hexadecadien-1-ol acetate, dinonanoin monocaprylin, 2-chloroethyl oleate, phenol,4-(1-phenylethyl)-, phenol,2,4-bis(1-phenylethyl)-, phenol-2-(1-phenylethyl)-, ethyl iso-allocholate and 1- monolinoleoylglycerol trimethylsilyl ether. The findings suggest that papaya leaf extracts have the ability to inhibit the growth of G. boninense, where a higher concentration of the extract exhibits better inhibition effects.

Regression analysis for yield loss of oil palm due to Ganoderma disease

Oil palm industry is well-established in Malaysia as well in Indonesia. The industry is facing a devastating crop disease which is Ganoderma Basal Stem Rot Disease (BSR) or popularly known as Ganoderma disease caused by a fungal called as Ganoderma boninense. The objective of this study is to develop a yield loss model of oil palm due to the disease. Backward elimination based regression method was used in developing the yield loss model where the independent variables also include interaction categorical variables up to the second order of interaction. Residual analysis was conducted on the best model developed and it showed that the mean value and standard deviation of the standardized residuals were zero and one respectively. The distribution of the standardized residual was also normal, homoscedastic, no presence of outlier. The value of the mean absolute percentage error (MAPE) which was used to measure the forecast performance of the best model was considered reasonable forecasting. The yield loss model developed in this study can be used in estimating the economic loss as well as the economic advantage of any Ganoderma disease control.