Galactose oxidase/kelch repeat-containing protein is involved in the iron deficiency stress response in the roots of Hyoscyamus albus

To confirm the involvement of galactose oxidase/kelch repeat-containing protein (Glx) in response to iron (Fe) deficiency in Hyoscyamus albus, we cloned a putative full-length HaGlx cDNA, which contained an open reading frame (975 bp, 324 amino acids). HaGlx was confirmed by homology searches, molecular phylogeny analysis, and domain search. HaGlx was expressed in the roots but not in the leaves, and the expression significantly increased under Fe deficiency. Sequencing of ~1.9 kb of the 5ʹ-upstream region of the HaGlx gene, followed by the analysis of promoter elements, resulted in the identification of multiple rootspecific elements together with stress-induced elements, including the Fe deficiency-induced element (IDE1) core motif. This suggests that HaGlx plays a key role in stress responses induced under Fe deficiency in the roots. To our knowledge, this is the first report confirming, in a plant other than Arabidopsis thaliana, that Glx is involved in the stress response to Fe deficiency.