Download Varieties of Mugineic Acid Family Phytosiderophores Secreted from

Varieties of Mugineic Acid Family Phytosiderophores Secreted from Fe-deficient Foxtail Millet
and Gene Expression Related to Their Biosynthesis
Reiko Nakanishi ITAI1, Naoko K. NISHIZAWA2 and Hiromi NAKANISHI1*
1Laboratory
of Plant Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo
113-8657, Japan, 2Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural
University, 1-308 Suematsu, Nonoichi, Ishikawa, 921-8836, Japan
Graminaceous plants utilize mugineic acid family phytosiderophores (MAs) in Fe acquisition from
the soils and Fe translocation inside the body. Furthermore, MAs are significant for seed
maturation as well as Fe homeostasis in graminaceous plants. Foxtail millet (Setaria italica) is
the second-most widely planted species of millet and the most important in East Asia. Foxtail
millet is high in carbohydrates and a food rich in dietary fiber and minerals such as Fe. Genomic
sequencing of foxtail millet was completed in 20121). However, details of the Fe utilization in
foxtail millet are still unclear. For the first step of elucidating the Fe utilization in foxtail millet, we
surveyed the varieties of MAs secreted from its roots and the gene expression related to MAs
biosynthesis.
The root exudates from Fe-deficient plants of foxtail millet contained 2′-deoxymugineic acid
(DMA), mugineic acid (MA) and avenic acid A (AVA). Gene expression of the predicted genes
including nicotianamine synthase (NAS), nicotinamine aminotransferase (NAAT) and DMA
synthase (DMAS) were highly induced by Fe deficiency in both roots and shoots. That is to say,
foxtail millet showed a rice-type expression pattern of NASs, NAAT and DMAS, although foxtail
millet is a C4 plant as same as maize, which expresses those genes mainly in roots2,3). On the
other hand, a similar gene to barley IDS3, which is induced only in barley roots and whose
product converts DMA into MA, was not highly induced in shoots, indicating that synthesis of MA
in foxtail millet may be limited in roots.
Analyses of MAs production in foxtail millet suggested that MAs are utilized in Fe uptake from
the soils, while DMA was also important for the Fe homoeostasis in shoots.
Keywords: foxtail millet, MAs, IDS3
REFERENCES
1) Zhang G et al., Nat. Biotechnol. 2012. 30:549-54.
2) Inoue H et al., Plant J. 2003. 36:366–81.
3) Nozoye T et al., PLoS ONE 2013. 8: e62567.
Preferred Presentation format: POSTER.
Selected Sessions: (please, indicate the name of the session from these):
1 Fe acquisition, transport and distribution in plants
2 Iron and plant metabolism