セミナー情報

The process of iron (Fe) acquisition in plants has been well described, whereas little is known about intracellular Fe use efficiency. In order to identify further genes involved in Fe transport or Fe recycling in plants, we have conducted a yeast complementation approach. For this purpose the Fe uptake-defective yeast mutant fet3fet4 was transformed with a cDNA library from Arabidopsis. Among different membrane proteins isolated in this screening, expression of the SNARE AtVTI11 gene consistently recovered the growth of the fet3fet4 mutant on Fe-limiting medium. Interestingly, growth recovery was not associated with an increased Fe uptake capacity, but rather appeared to be mediated by a more efficient utilization of Fe reserves. In yeast cells, Fe deficiency induced autophagy.  In roots of Fe-deficient Arabdopsis plants, AtVTI11 mRNA levels were upregulated and current investigations address the question whether Fe deficiency also induces autophagy in plants. A vti1-1 (zig-1) mutant and an autophagy defective mutant atg18a showed more severe Fe deficiency chlorosis when grown under low Fe availability. We are currently analyzing the role of VTI11 in intracellular iron efficiency in Arabidopsis plants and hypothesize that VTI1-type SNARE proteins are limiting factors for the efficient turnover of Fe-containing proteins via autophagy upon Fe deficiency.