Differential regulation of cadmium-inducible expression of iron-deficiency-responsive genes in tobacco and barley

• Published in: Physiologia plantarum Vol. 129; no. 3; pp. 622 - 634
• Main Authors: Hodoshima, Hirotaka, Enomoto, Yusuke, Shoji, Kazuhiro, Shimada, Hiroaki, Goto, Fumiyuki, Yoshihara, Toshihiro
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.03.2007; Blackwell Publishing Ltd; Blackwell
• Subjects: Biological and medical sciences; Cell physiology; Fundamental and applied biological sciences. Psychology; Molecular and cellular biology; Signal transduction; Monocotyledones; Spermatophyta; Gene; Hordeum vulgare; Gramineae; Angiospermae
• ISSN: 0031-9317; 1399-3054
• DOI: 10.1111/j.1399-3054.2006.00825.x

The expression of four representative iron-deficiency-responsive genes from tobacco (NtIRT1 and NtYSL1) and barley (HvIDS2 and HvYS1) plants were evaluated in each host plant in response to iron deficiency (ΔFe), cadmium exposure (+Cd) or both (ΔFe + Cd). These conditions significantly enhanced NtIRT1 and HvIDS2 expression in roots, whereas NtYSL1 and HvYS1 expression was similar in shoots and roots. NtIRT1 expression under +Cd and ΔFe + Cd was lower than that under ΔFe, whereas the expression of NtYSL1, HvIDS2 and HvYS1 in roots under +Cd and ΔFe + Cd was similar or higher than that under ΔFe. A time-course experiment showed that NtIRT1 expression under +Cd and ΔFe was regulated similarly throughout the experiment [expressed between 3 and 21 days after treatment (DAT)]. NtYSL1 expression under +Cd and ΔFe began at 1 DAT; expression soon disappeared under ΔFe, whereas it continued to 21 DAT under +Cd. The timing of HvIDS2 and HvYS1 expression under +Cd (between 1 and 5 DAT) was earlier than that under ΔFe (between 5 and 21 DAT). Notably, no Fe deficit occurred in any parts of these plants when grown under +Cd, except for tobacco shoots, even when the genes were highly expressed. Thus, some expression under +Cd differed from that under ΔFe. It is possible that both the genuine Fe-deficiency-responsive mechanism and an unidentified mechanism, which can be directly regulated by Cd, contribute to gene expression to maintain metal homeostasis within the plant.