IDENTIFICATION OF BASAL STEM ROT (BSR) BIOMARKER BASED ON FIELD SEVERITY INDICES ON GANODERMA BONINENSE PAT. INFECTED OIL PALM STEM TISSUE BY 1H NMR-BASED METABOLOMICS ANALYSIS

• Main Author: Marchantia Karima, Elfina
• Format: Theses
• Language: Indonesia
• Subjects: Teknologi
• Online Access: https://digilib.itb.ac.id/gdl/view/80573
• Institution: Institut Teknologi Bandung

Basal Stem Rot Disease (BSR) caused by infection with Ganoderma boninense Pat. is a disease that mainly affects oil palm plants in Southeast Asia. This disease can be fatal to palm oil production, particularly the world's largest palm oil exporting countries, including Indonesia. In the early stages of infection, BSR disease shows no signs or symptoms on the tree, so detecting this disease is quite difficult. Therefore, an approach capable of detecting BSR disease in oil palms is needed, especially at any disease severity level in the field. This study aims to identify biomarkers of BSR disease in oil palm stem tissue based on various disease severity indices in the field using 1H NMR based metabolomics analysis. Oil palm stem tissue with four disease severity indices, namely Index 1 (healthy), Index 2 (moderate healthy), Index 3 (moderate severe), and Index 4 (severe), was analyzed using methanol:water (80:20, v/v). The crude extract obtained was then analyzed by means of 500 MHz 1H NMR spectroscopy. Data analysis performed in this study included spectral preprocessing (Mestrenova 8.0), metabolite identification (ASICS R Package version 4.0.2), multivariate statistical analysis using Principal Component Analysis (PCA), Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) methods, Partial Least Squares Discriminant Analysis (PLS-DA), Receiver Operating Characteristics (ROC) Analysis and Pathway Analysis (MetaboAnalyst 5.0). Confirmation of compound identification was performed by manual 1 H NMR spectral analysis. From the analysis results, 90 metabolites from oil palm stem tissue were identified and 20 of them were identified as metabolites that could significantly discriminate the four disease severity indices (VIP score > 1.0). These metabolites include organic acid groups, carbohydrate groups,organoheterocyclic compound groups, and benzenoid groups. Some organic acid compounds such as taurine and L-aspartate have relatively high concentrations at index 1 but very low concentrations at index 4. Carbohydrate groups such as threonic acid, Larabitol and D-fructose and organoheterocyclic compounds such as allantoin have the highest concentrations at index 1 in comparison to other indices. In index 2, several groups of organic acid compounds (guanoacetic acid, L-asparagine and Lcysteine), carbohydrate groups (D-gluconic acid, xylitol and D-mannose) and benzenoid groups (4-hydroxyphenylacetic acid). ) had the highest concentration compared to the other groups. Meanwhile, at index 3, only the benzenoid group, namely 2-hydroxyphenylacetic acid, had the highest concentration. In contrast to the severity of other diseases, at index 4 almost all significant compounds had very low relative concentrations. This occurs in the group of organic acid compounds, carbohydrates, organo-heterocyclic compounds and benzoids. The results of the PCA analysis showed differences in the metabolite profile between the healthy index (1) and various other disease severity indices. From the results of the OPLS-DA method and ROC analysis (VIP score > 1; AUC value = 1.0) it was identified biomarkers from groups of organic acids, carbohydrates, organoheterocyclic compounds, organic nitrogen compounds and benzene consisted in the four degrees of disease severity indices. Based on a pathway analysis using the KEGG database, there are 5 pathways in oil palm that are potentially affected by BSR disease (p-value < 0.05 and pathway impact > 0.1), namely the arginine Biosynthetic pathway, alanine pathway, alanine pathway, aspartate and glutamate, glycerol, serineand threonine pathways, and arginine and proline pathways. The results of the study revealed differences in the profiles and relative concentrations of oil palm stem tissue metabolites at each BSR disease severity level. Biomarkers can be identified from each disease severity index and used for diagnostic purposes. Analysis of the oil palm signaling pathways involved in this research can be used as a reference for further studies, including genomic and transcriptomic studies.