2005 Volume 55 Issue 2 Pages 213-222
The objective of the present study was to develop a functional crop that could contribute to the maintenance and improvement of human health by the introduction of the human lactoferrin (hLF) gene. Lactoferrin is an 80-kDa iron-binding glycoprotein that has been considered to play many biological roles, including the regulation of iron absorption, protection against microbial and virus infection, stimulation of the immune system and cellular growth promotion. We introduced two different constructs containing either the native signal peptide from human lactoferrin (pIG211) or the signal peptide from rice glutelin (pIG200) fused to mature human lactoferrin into Javanica rice cv. Rojolele by using the Agrobacterium-mediated transformation system. The expression of the hLF gene under the control of the maize ubiquitin-1 promoter was detected in all the tissues of the transgenic plants. We found that the transgenic rice plants IG200R produced a considerable amount of recombinant hLF (rhLF) in seeds, accounting for approximately 15% of the total soluble protein (TSP). RhLF was purified from mature seeds by cation-exchange chromatography. Amino acid sequencing confirmed that the N-terminal sequences of rhLF for both constructs were identical with those of native LF from human milk. Rice rhLF showed a slightly smaller molecular weight than the native hLF. Immunofluorescence microscopy revealed that rhLF was located in the intracellular and intercellular regions of endosperm cells. Protein extracts from transgenic rice seeds exhibited an antibacterial activity against Bacillus subtilis ATCC6633. The use of signal peptides and a constitutive ubiquitin-1 promoter for successful production of transgenic Javanica rice expressing a high level of rhLF was examined.
