Abstract
It is thought iron uptake is mainly regulated by long-distance signals sent from shoots. Expression of iron uptake genes coding iron regulated transporter (NtIRT1) and ferric chelate reductase (NtFRO1) are induced in roots of iron deficient tobacco. To elucidate the role of the signals for iron uptake in roots, we performed the expression analysis of the genes in intact tobacco plants with leaf excision and hairy roots under various conditions. In consequence, it was suggested that the iron uptake is regulated by promotive signals which are synthesized in iron deficient leaves regardless of leaf position and sent to roots. Meanwhile iron deficient hairy roots induce the gene expression, suggesting that roots have their own iron sensor and regulate iron uptake. We propose the most appropriate model that iron uptake signals are synthesized in whole plants and the amount of the signals correlates with the size of plants.
