Genomic and Metabolomic Profiling of a Rice Core Collection That Exhibit Variable Effects On Lymphoma.

Rice (Oryza sativa) is an agronomically important food crop and a valuable model system for cereal genetics. Ten varieties from a rice core collection were screened for genetic variation in four classes of nutritionally important metabolites: phenolics, vitamin E, phytosterols, and linolenic acid. Single nucleotide polymorphisms (SNPs) in each pathway were identified using the Ricecyc and OryzaSNP databases (www.gramene.org, www.oryzasnp.org). A number of SNPs in all four pathways were classified as nonsynonymous or within the 5’ and 3’ untranslated regions. Cooked brown rice metabolites were then detected by ultra performance liquid chromatography coupled to mass spectrometry. Multivariate analyses of metabolite profiles cluster varieties according to previously defined genetic and morphological diversity, suggesting genetic control of the type and quantity of metabolites in cooked rice. Total phenolics and vitamin E were measured and large differences among the varieties were observed, including the relative contributions of alpha and gamma tocopherol in the total pool of vitamin E. Rice bran extracts from multiple varieties were screened for bioactivity using human lymphoma in cell-based assays. Rice bran among varieties displayed differential effects on lymphoma viability and proliferation. The bioavailability of dietary rice bran compounds is being assessed using healthy and tumor-bearing mice and canines. The observed genetic and metabolite variation in nutritionally-relevant metabolite pathways may support future crop improvement for health quality in rice breeding programs.