Deoxymugineic acid increases Zn translocation in Zn-deficient rice plants.
Deoxymugineic acid (DMA) is a member of the mugineic acid family phytosiderophores (MAs), which are natural metal chelators produced by graminaceous plants. Rice secretes DMA in response to Fe deficiency to take up Fe in the form of Fe(III)-MAs complex. In contrast with barley, the roots of which secrete MAs in response to Zn deficiency, the amount of DMA secreted by rice roots was slightly decreased under conditions of low Zn supply. There was a concomitant increase in endogenous DMA in rice shoots, suggesting that DMA plays a role in the translocation of Zn within Zn-deficient rice plants. The expression of OsNAS1 and OsNAS2 was not increased in Zn-deficient roots but that of OsNAS3 was increased in Zn-deficient roots and shoots. The expression of OsNAAT1 was also increased in Zn-deficient roots and dramatically increased in shoots; correspondingly, HPLC analysis was unable to detect nicotianamine in Zn-deficient shoots. The expression of OsDMAS1 was increased in Zn-deficient shoots. Analyses using the positron-emitting tracer imaging system (PETIS) showed that Zn-deficient rice roots absorbed less (62)Zn-DMA than (62)Zn(2+). Importantly, supply of (62)Zn-DMA rather than (62)Zn(2+) increased the translocation of (62)Zn into the leaves of Zn-deficient plants. This was especially evident in the discrimination center (DC). These results suggest that DMA in Zn-deficient rice plants has an important role in the distribution of Zn within the plant rather than in the absorption of Zn from the soil.
Suzuki
Motofumi
M
Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Tsukamoto
Takashi
T
Inoue
Haruhiko
H
Watanabe
Satoshi
S
Matsuhashi
Shinpei
S
Takahashi
Michiko
M
Nakanishi
Hiromi
H
Mori
Satoshi
S
Nishizawa
Naoko K
NK
D019883:Alkyl and Aryl Transferases / Q000235:genetics / Q000378:metabolism; D001383:Azetidinecarboxylic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D015152:Blotting, Northern; D007501:Iron / Q000378:metabolism; D009536:Niacinamide / Q000378:metabolism; D012275:Oryza / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism; D000637:Transaminases / Q000235:genetics / Q000378:metabolism; D015032:Zinc / Q000378:metabolism*
D010940:Plant Proteins; D009536:Niacinamide; D001383:Azetidinecarboxylic Acid; D007501:Iron; D019883:Alkyl and Aryl Transferases; C118230:nicotianamine synthase; D000637:Transaminases; D015032:Zinc; C052863:mugineic acid