Physiological and Transcriptome Analyses of Transgenic FGF21 Immature Rice Seeds

In addition to its role as one of the largest staple food crops in the world, rice (Oryza sativa L.) currently serves as an important bioreactor in molecular pharming. Although some studies have been conducted on the effects of foreign protein expression on rice, most of them use mature seeds and focus on proteomic changes. In this study, the effects of fibroblast growth factor 21 (FGF21) transformation on immature rice seeds were studied by means of physiological and transcriptome sequencing method. Starch and sucrose content and their associated enzyme activities of immature seeds were determined. After extracting RNA from immature seeds, Illumina HiSeqTM 2500 was used for RNA sequencing. The content of starch and sucrose and activities of related enzymes in transgenic FGF21 immature rice seeds were greater than those of wild type. In total, 1762 differentially expressed genes (DEGs) were identified among non-transgenic wild type (CK) and transgenic lines (T1, T2, and T3). Meanwhile, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that the top two enriched processes were starch and sucrose metabolism and plant–pathogen interactions. Most DEGs of the plant–pathogen interactions pathway were downregulated, while expression patterns were more complex for DEGs of starch and sucrose metabolic pathways. Ultimately, these results could be used to reveal mechanisms underlying transgenic seed quality changes induced by FGF21 transformation and could also serve as an exploratory study into the use of transcriptome technique for safety evaluation of rice bioreactors.