Background: Sago palm is an important agricultural starch-producing crop in Malaysia. The trunk of sago palm is responsible for the production of the starch reaching maturity for harvesting after ten years. However, there are sago palms that failed to develop its trunk after 17 years being planted. This is known as a stressed “non-trunking” sago palm, which eliminates the economic value of the palms. Objective: The study was initiated to compare the differences in metabolite expression between trunking and non-trunking sago palm and secondly to determine the potential metabolite-makers that are related to differential phenotypes of sago palms. Method: Metabolites were extracted using various solvents and analysed using NMR spectroscopy and GC-MS spectrometry. Data obtained were subjected to principal component analysis. Results: The study determined that differential metabolites expression were detected in the leaf extracts of normal trunking sago palm compared to the non-trunking palms. Metabolite groups which are differently expressed between trunking and non-trunking sago palm are oils and waxes, haloalkanes, sulfite esters, phosphonates, phosphoric acid, thiophene ester, terpenes and tocopherols. GC-MS analysis of Jones & Kinghorn extraction method determined two sets of metabolite markers which explains the differences in metabolites expression of trunking and non-trunking sago palm in ethyl acetate and methanol extract of 89.55% comprising sulfurous ester compounds and 87.04% comprising sulfurous ester, sulfurous acid and cyclohexylmethyl hexyl ester respectively. Conclusion: Two sets of metabolite markers were expressed in the trunking and non-trunking sago palm. These metabolites can potentially be used as markers for identifying normal and stressed plants.

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In the state of Sarawak, Malaysia's vast peatland cultivated with sago palm (Metroxylon sagu), a considerable amount of cases involving stunted, nondeveloped trunk of sago palms was observed. Molecular-level understanding of the mechanism or pathway involved in the trunking (T) process leading to storage starch accumulation in the trunk of the sago palm is yet to be fully understood. A Polymerase Chain Reaction-based differential display analysis using Annealing Control Primer based GeneFishing technique on leaf samples of normal T compared to the nontrunking (NT) palm showed distinct differentially expressed transcripts pattern with differences in intensity between 35% and 123%. The translated sequence identified functions that are grouped under energy metabolism, nutrient regulation, biosynthetic reactions, defense mechanism, and stress tolerance. Transcripts from T showed higher expression of redox-regulating functions, while NT samples had proteins actively involved in the respiratory chain and chloroplast regulation. In nutrient regulation, the T sample showed higher transcript levels of nitrogen utilization and regulation of phosphate and cobalt, whereas NT showed activities of nitrogen uptake and regulation of calcium, magnesium, and zinc. This study identified different levels of transcripts in two physiologically different sago palms, and the formation and the development of the trunk are induced by these enzymes.