Title: Integrated Transcriptomics, Proteomics, and Metabolomics analyses to survey ozone responses in the leaves of rice seedling

Summary: Ozone (O3), a serious air pollutant, is known to significantly reduce photosynthesis, growth, and yield and to cause foliar injury and senescence. Here, integrated transcriptomics, proteomics, and metabolomics approaches were applied to investigate the molecular responses of O3 in the leaves of 2-week-old rice (cv. Nipponbare) seedlings exposed to 0.2 ppm O3 for a period of 24 h. On the basis of the morphological alteration of O3-exposed rice leaves, transcript profiling of rice genes was performed in leaves exposed for 1, 12, and 24 h using rice DNA microarray chip. A total of 1535 non redundant genes showed altered expression of more than 5-fold over the control, representing 8 main functional categories. Genes involved in information storage and processing (10%) and cellular processing and signaling categories (24%) were highly represented within1h of O3 treatment; transcriptional factor and signal transduction, respectively, were the main subcategories. Genes categorized into information storage and processing (17, 23%), cellular processing and signaling (20, 16%) and metabolism (18, 19%) were mainly regulated at 12 and 24 h; their main subcategories were ribosomal protein, posttranslational modification, and signal transduction and secondary metabolites biosynthesis, respectively. Two dimensional gel electrophoresis-based proteomics analyses in combination with tandem mass spectrometer identified 23 differentially expressed protein spots (21 non redundant proteins) in leaves exposed to O3 for 24 h compared to respective control.Identified proteins were found to be involved in cellular processing and signaling (32%), photosynthesis (19%), and defense (14%). Capillary electrophoresis-mass spectrometry-based metabolomic profiling revealed accumulation of amino acids, gamma-aminobutyric acid, and glutathione in O3 exposed leaves until 24 h over control. This systematic survey showed that O3 triggers a chain reaction of altered gene, protein and metabolite expressions involved in multiple cellular processes in rice.

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Reference: Cho, K., Shibato, J., Agrawal, G.K., Jung, Y.H., Kubo, A., Jwa, N.S., Tamogami, S., Satoh, K., Kikuchi, S., Higashi, T. and Kimura, S., 2008. Integrated transcriptomics, proteomics, and metabolomics analyses to survey ozone responses in the leaves of rice seedling. Journal of proteome research, 7(7), pp.2980-2998.