Tissue Expression Pattern Analysis Of Fe(Ⅲ)-Chelate Reductase Gene Family In Arabidopsis Thaliana

Iron is an essential element required for respiration, photosynthesis, and many other cellular such as DNA synthesis, nitrogen fixation, and hormone production. Iron deficiency disturbs not only the normal growth of plant, but also the metabolism of animals and human beings. Iron deficiency is among the most common nutritional disorders in plants. However, excess of iron also can cause serious damage to plants because free iron catalyzes the formation of reactive oxygen species. Therefore, to control their iron homeostasis, multicelluar organisms have to balance iron uptake, intracellular compartmentalization, portioning to the various organs and storage. Plants have evolved two main strategies to cope with iron-deficient growth conditions. Dicot and monocot plants with the exception of grasses mobilize iron through iron reduction (strategy I) as opposed to grasses that utilize a phytosiderophore based iron chelation mechanism (strategy II).Strategy I includes the induction of iron-reductase activity at the root surface of the root-hair zone, proton extrusion, the activation of a high-affinity transport system for the uptake of Fe(II) in the root epidermis, and root-hair proliferation at the root tip. Strategy I responses are tightly regulated in response to iron availability. In the genome of Arabidopsis thaliana there are eight genes classified into the iron-chelate reductase gene family (AtFROs) based on sequence homology with AtFRO2 (a ferric-chelate reductase in Arabidopsis). They are localized on chromosome 1 (3 AtFROs) and chromosome 5 (5 AtFROs) of Arabidopsis and show high similarity of amino acid sequences to each other. The eight genes have all the character of iron-chelate reductase and different iron reduction activity. As genes expressed in which part of the plant, nobody did detailed research. So the tissue specific expression of the genes was studied in the paper.The main results were as follows: We have got a lot of transgenic plant lines. And we found AtFRO2 displayed the highest iron-reduction activity among the AtFROs investigated, further demonstrating that AtFRO2 is a major iron reductase gene in Arabidopsis. AtFRO2 and AtFRO3 were mainly expressed in roots of Arabidopsis, AtFRO5 and AtFRO6 in shoots and flowers, AtFRO7 in cotyledons and trichomes whereas the transcription of AtFRO8 was...