1H NMR metabolomics analysis of leaf tissue from oil palms against Ganoderma boninense

Abstract

Introduction Breeding for oil palm resistance against basal stem rot caused by Ganoderma boninense is challenging and lengthy. Advanced oil palm gene pools are very limited hence it is assumed that parental palms have experienced genetic drift and lost their resistance genes against Ganoderma. High-throughput selection criteria should be developed. Metabolomic analysis using ¹H Nuclear Magnetic Resonance (NMR) is known to be easy to prepare and the produced metabolite could be used as a diagnostic tool for disease incidents in various host-pathogen combinations. Objectives The study objective is to identify metabolite variations of Dura (D) and Pisifera (P) parental palms with different resistance against Ganoderma and moderately resistant Tenera (DxP) using ¹H NMR analysis Methods Leaf tissues of seven different oil palm categories consisting of: resistant, moderate, and susceptible Dura (D), moderate and susceptible Pisifera (P), resistant Tenera/Pisifera (T/P) progenies, and moderately resistant DxP variety progenies were sampled and determined their metabolites using NMR spectroscopy. Results Twenty-nine types of metabolites were identified and most of the metabolites fall in the monosaccharides, amino acid, and fatty acids compound classes. The PCA, PLS-DA, and heatmap multivariate analysis indicated that there were two identified groups of resistances based on their metabolites. The first group consisted of resistant T/P, moderate P, resistant D, and moderately resistant DxP. In contrast, the second group consisted of susceptible P, moderate D, and susceptible D. Glycerol and ascorbic acid were detected as a biomarker candidate by OPLS-DA to differentiate moderately resistant DxP against susceptible D and P. The pathway analysis suggested that the glycine, serine, and threonine metabolism and taurine and hypotaurine metabolism were involved in the oil palm defense mechanism against Ganoderma. Conclusion Metabolomic study with ¹H NMR was able to describe the metabolites composition that could differentiate the characteristics of oil palm resistance against basal stem rot caused by Ganoderma boninense. These metabolites revealed in this study had enormous potential to become support tools to breed new oil palm varieties with higher resistance against basal stem rot.