Abstract
Nicotianamine (NA) is a biosynthetic precursor to mugineic acid family phytosiderophores (MAs) and thus nicotianamine synthase (NAS) is a critical component in the iron acquisition strategy of graminaceous plants. NA, which is structurally similar to MAs and is also a strong chelator of various transition metals, is ubiquitously present in higher plants. Therefore, it is thought that NA is a key component in transition metal homeostasis in non-graminaceous plants. We isolated three NAS genes (AtNAS1, 2 and 3) from Arabidopsis. To elucidate the physiological functions of the three AtNAS genes in Arabidopsis, we examined the expression of AtNAS1, AtNAS2 and AtNAS3 by promoter:β-glucuronidase analysis and quantitative RT-PCR. Expression of AtNAS1 and AtNAS2 were induced by iron deficiency. In contrast, expression of AtNAS3 was suppressed by iron deficiency. Therefore, three NAS genes were differentially regulated by iron in Arabidopsis.
