Book with abstracts from the COST Action 0905 meeting in ... - UMB
Book with abstracts from the COST Action 0905 meeting in ... - UMB
Book with abstracts from the COST Action 0905 meeting in ... - UMB
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CHARACTERIZATION OF ARABIDOPSIS MUTANTS AFFECTED IN<br />
SEED IRON STORAGE.<br />
Viviane Mary 1 , Magali Schnell Ramos 1 , Jérôme Giraudat 1 , Hicham Khodja 2 , Sébastien<br />
Thom<strong>in</strong>e 1<br />
1 Institut des Sciences du Végétal, CNRS, Gif-sur-Yvette, France,<br />
2 CEA, IRAMIS, SIS2M, LEEL and CNRS, UMR 3299, SIS2M, LEEL, F-91191 Gif-sur-<br />
Yvette, France.<br />
Keywords: Iron, Mutants, Seed, Transport, Vacuole.<br />
To improve seed iron (Fe) content and availability, it is crucial to decipher <strong>the</strong> mechanisms<br />
which control Fe storage dur<strong>in</strong>g seed development. In Arabidopsis thaliana seeds, Fe is<br />
stored <strong>in</strong> <strong>the</strong> vacuoles of cells surround<strong>in</strong>g <strong>the</strong> vasculature of <strong>the</strong> embryo. The AtVIT1<br />
transporter is <strong>in</strong>volved <strong>in</strong> Fe <strong>in</strong>flux <strong>in</strong>to vacuoles (Kim et al., Science 314:1295-98), while<br />
AtNRAMP3 and AtNRAMP4 function redundantly <strong>in</strong> Fe retrieval <strong>from</strong> vacuoles dur<strong>in</strong>g<br />
germ<strong>in</strong>ation (Lanquar et al., EMBO J. 24:4041-51). When germ<strong>in</strong>ated under Fe deficient<br />
conditions, nramp3nramp4 double mutant development is arrested as a consequence of<br />
impaired Fe mobilization.<br />
To identify novel genes <strong>in</strong>volved <strong>in</strong> seed Fe homeostasis, we screened an EMS<br />
mutagenized population of nramp3nramp4 for mutations restor<strong>in</strong>g <strong>the</strong> growth of<br />
nramp3nramp4 seedl<strong>in</strong>gs on low Fe. In parallel to <strong>the</strong>ir genetic characterization, we<br />
classified <strong>the</strong> mutant candidates based on <strong>the</strong>ir seed Fe content and Fe localization pattern.<br />
Among <strong>the</strong>m, two mutants display a pattern of Fe localization similar to <strong>the</strong> vit1-1<br />
knockout mutant and carry mutations <strong>in</strong> <strong>the</strong> AtVIT1 gene. This result establishes a<br />
functional l<strong>in</strong>k between Fe load<strong>in</strong>g <strong>in</strong> vacuoles by AtVIT1 and its retrieval by AtNRAMP3<br />
and AtNRAMP4. O<strong>the</strong>r mutants <strong>with</strong> dist<strong>in</strong>ct Fe localization patterns and contents are<br />
currently under <strong>in</strong>vestigation.