Constitutive expression of soybean ferritin cDNA intransgenic wheat and rice results in increased iron levels in vegetative tissues but not in seeds

We used particle bombardment to produce transgenic wheat and rice plants ex pressing recombinant soybean ferritin, a protein that can store large amoun ts of iron. The cDNA sequence was isolated from soybean by RT-PCR and expre ssed using the constitutive maize ubiquitin-1 promoter. The presence of fer ritin mRNA and protein was confirmed in the vegetative tissues and seeds of transgenic wheat and rice plants by northern and western blot analysis, re spectively. The levels of ferritin mRNA were similar in the vegetative tiss ues of both species, but ferritin protein levels were higher in rice. Both ferritin mRNA and protein levels were lower in wheat and rice seeds. ICAP s pectrometry showed that iron levels increased only in vegetative tissues of transgenic plants, and not in the seeds. These data indicate that recombin ant ferritin expression under the control of the maize ubiquitin promoter s ignificantly increases iron levels invegetative tissues, but that the level s of recombinant ferritin in seeds are not sufficient to increase iron leve ls significantly over those in the seeds of non-transgenic plants.