Liquid Chromatography-Mass Spectrometry (LC/MS) based Metabolomic Fingerprinting in Contrasting Rice Varieties for Iron (Fe) excess.

• Ultra-high-performance liquid chromatography- mass spectrometry (UPLC-MS) based untargeted metabolomics is performed for the two contrasting rice varieties with different comparative response against iron toxicity. • Under the influence of positive ESI mode, 1022 metabolites in shoot and 707 metabolites in root were filtered out for observation based upon their intensities provisionally annotated through METLIN. • Under excess iron in the medium, rice plant showed downregulation of organic acids like, oxoglutaric acid, ketoglutaramic and succinic acid. • Secondary metabolites like flavanoids, phenolics and polyphenolics contributes in establishing antioxidant responses under various biotic and abiotic stresses. Rice is an important cereal which is grown worldwide covering the requirement of 50% of the world population as the staple food. Diverse abiotic factors act as a limiting factor for its yield annually and can challenge sustainable productivity of the crop. Iron is an important micronutrient for plants participating in biochemical reactions including electron transport chain. Under the impact of excess iron in the rhizosphere, plants are posed with iron toxic condition. Most of the lowland rice is cultivated in submerged condition leading to accumulation of Fe 2+ in the soil which is the toxic form for uptake and in turn can affect the yield of the crop. Present work is an extension of previously performed transcriptomic analysis of Northeast India lowland rice varieties under excess iron treatment using ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS). In total 1105 peaks were detected for each root and shoot. Multivariate analysis based upon principal component analysis (PCA; PCA1 and PCA2) are accounted for 70.6% of the total variation in root and 77.2% in shoot. The metabolomics profiling has indicated significant alteration in primary and secondary metabolites. Majority of the secondary metabolites like quercetin, malvin, flavanones, delphinidin are upregulated indicating their role in anti-oxidative properties during iron toxicity. On the other hand, chelators of ferric ion like mugineic acid are down regulated to avoid excess iron uptake. This work is a comparative insight on the metabolic front in case of iron excess tolerance in contrasting lowland rice varieties.