ARABIDOPSIS Atfer1 PROMOTER INDUCTION DURING SENESCENCE IS INDEPENDENT FROM THE IDRS ELEMENT

Ferritins are ubiquitous, multimeric, iron-storage proteins. Plant ferritins are localised in the chloroplasts and are mainly regulated at transcriptional level. Several stresses induce ferritin accumulation, like iron loading, photooxidative stress, abscissic acid. In Arabidopsis thaliana four different ferritin genes have been identified: Atfer1, 2, 3, and 4. Arabidopsis Atfer1 promoter contains an Iron Dependent Regulatory Sequence (IDRS) responsible for transcriptional repression under low iron supply. We investigated of Atfer1 involvement during different stress conditions by using two Arabidopsis transgenic lines transformed with a construct in which the 1600 bp Atfer1 promoter, with either the native or a mutagenised IDRS, is upstream the GUS reporter gene. Our preliminary results suggest that photoinhibition, methyl jasmonate, wounding or cold treatments do not induce Atfer 1 gene transcription. One of the other Arabidopsis ferritins (Atfer 2, 3, 4) are induced during photoinhibition, as we have already shown a ferritin transcript accumulations during this kind of stress. On the contrary Atfer1 gene transcription is induced during senescence; most important, that induction is IDRS independent. Regulatory elements, distinct from the IDRS one, are therefore required to regulate ferritin levels during senescence