Endosperm tissue is good production platform for artificial recombinant proteins in transgenic rice

Transgenic rice plants expressing 7Crp peptide were generated by Agrobacterium-mediated transformation. The 7Crp peptide is the hybrid peptide of seven major human T-cell epitopes derived from Japanese cedar pollen allergens Cry j 1 and Cry j 2. When the 7Crp gene was expressed under the control of the rice AGPase large subunit or maize ubiquitin-1 promoters, it could only be detected in the endosperm of rice seed, although high levels of RNA transcript were observed in the leaf, stem, and seed embryo. It was demonstrated by confocal and electron microscopy analysis that the 7Crp peptide was mainly localized in the endoplasmic reticulum-derived protein bodies, designated protein body I (PB-I). Our results indicate that rice endosperm tissue has advantage over other tissues as a production platform for foreign recombinant proteins.