Abstract: Using gas chromatograph-mass spectrometry (GC-MS)-based metabolomics, we investigated 60 rice samples collected from two geographical indication rice-producing regions in Heilongjiang province. The SIMCA software and the R software were used to analyze the obtained data by multivariate statistical analysis and metabolic pathway analysis such as principal component analysis (PCA), orthogonal partial least square discriminant analysis (OPLS-DA). We explored the effect of the geographical origin on rice metabolism and metabolites. A total of 167 metabolites were identified, and our analysis revealed that the geographical origin affected the number, type, and content of rice metabolites, having the most significant effect on the content. A total of 32 differential metabolites were identified, and hierarchical cluster analysis showed that they could be used as a reference index for identification of the geographical origin of rice. The OPLS-DA results showed a clear discrimination between rice samples from the two producing regions, and the samples showed a significantly clustered distribution, indicating that the geographical origin had a great influence on rice metabolism. Metabolic pathway analysis found that nine key pathways were highly correlated with the differential metabolites. We determined that the geographical origin had the greatest impact on the metabolism of lipids and amino acids in rice. The five metabolites of ureapropionic acid, squalene, cholesterol, lauric acid and fumaric acid could be of great reference significance for understanding the metabolic differences of rice from different producing regions. This research provides a theoretical basis for the identification of rice from different producing region and a reference for tracing the geographical origin of agricultural products.

Key words: metabolomics; gas chromatography-mass spectrometry; rice; producing area