Stress responsive proteins are actively regulated during rice (<em>Oryza sativa</em>) embryogenesis as indicated by quantitative proteomics analysis

Embryogenesis is the beginning of a plants life, and the molecular changes that occur during embryonic development are largely unknown. To explore the relevant molecular events, we used the isobaric tags for relative and absolute quantification (iTRAQ) coupled with shotgun proteomics technique (iTRAQ/Shotgun) to study the proteomic changes of rice embryos during embryogenesis. For the first time, a total of 2,165 unique proteins were identified in rice embryos by using the Q-Exactive Mass spectrometry, and the abundances of 867 proteins were actively changed based on statistical evaluation towards the quantitative MS/MS signals. The quantitative data were then confirmed by using multiple reactions monitoring (MRM) conducted on Qtrap 5500 Mass spectrometry. To make the study reproducible by others, all of the raw Q-Exactive and Qtrap 5500 data had been deposited in the GigaScience database (GigaDB).<br>By using the WENGOsoftware, we further analyze the GO distribution of the identified embryo proteins. In the molecular functional group, the identified proteins that work as metabolic enzymes, binding (protein binding, nucleotide binding) and transporter are ranked at the top of the category. In the biological process categorization, the proteins that participate in metabolic and response to stimulus process are at the top ratio in the identified embryo proteins.