Altered levels of mitochondrial NFS1 affect cellular Fe and S contents in plants.

Key message: The ISC Fe–S cluster biosynthetic pathway would play a key role in the regulation of iron and sulfur homeostasis in plants. The Arabidopsis thaliana mitochondrial cysteine desulfurase AtNFS1 has an essential role in cellular ISC Fe–S cluster assembly, and this pathway is one of the main sinks for iron (Fe) and sulfur (S) in the plant. In different plant species it has been reported a close relationship between Fe and S metabolisms; however, the regulation of both nutrient homeostasis is not fully understood. In this study, we have characterized AtNFS1 overexpressing and knockdown mutant Arabidopsis plants. Plants showed alterations in the ISC Fe–S biosynthetic pathway genes and in the activity of Fe–S enzymes. Genes involved in Fe and S uptakes, assimilation, and regulation were up-regulated in overexpressing plants and down-regulated in knockdown plants. Furthermore, the plant nutritional status in different tissues was in accordance with those gene activities: overexpressing lines accumulated increased amounts of Fe and S and mutant plant had lower contents of S. In summary, our results suggest that the ISC Fe–S cluster biosynthetic pathway plays a crucial role in the homeostasis of Fe and S in plants, and that it may be important in their regulation. [ABSTRACT FROM AUTHOR]