アラビドプシスの2価鉄イオントランスポーターであるIRT1はニッケルの過剰集積に関わっている(三重大学 西田、水野ら)

Date: 2017-12-17 (Sun)

アラビドプシスの2価鉄イオントランスポーターであるIRT1はニッケルの過剰集積に関わっている(三重大学 西田、水野ら)
AtIRT1, the Primary Iron Uptake Transporter in the Root, Mediates Excess Nickel Accumulation in Arabidopsis thaliana
Sho Nishida1, Chisato Tsuzuki2, Aki Kato2, Ayaka Aisu2, Junko Yoshida2 and Takafumi Mizuno
Plant Cell Physiol. 52(8): 1433–1442 (2011) doi:10.1093/pcp/pcr089

筆者はうっかりしてこの論文を知らなかったのだが、最近刊行された日本土壌肥料学雑誌の 水野直治氏(元酪農学園大学獣医学研究科)の回顧録である 「蛇紋岩土壌研究のこぼれ話」 という名文の中に出てくる“引用文献欄”で、この論文を知った。

Nickel (Ni) is an essential nutrient for plants, but excessive amounts can be toxic. Ni competes with iron (Fe) in vivo, raising the possibility that Ni is competitively taken up via the Fe uptake system in plants. Here, we show evidence that AtIRT1, the primary Fe2+ uptake transporter in the root, mediates Ni accumulation in Arabidopsis thaliana. In hydroponic cultures, excess Ni exposure increased Fe accumulation and the relative transcription level of AtIRT1 in roots, indicating that excess Ni induces AtIRT1 expression in roots. An Fe-deficient treatment increased Ni accumulation in plants, suggesting that excess Ni was absorbed via the Fe uptake system, which was induced by Fe starvation. Moreover, Ni accumulation under Fe-deficient conditions was markedly lower in AtIRT1-defective mutants than in the wild-type, Col-0. Furthermore, AtIRT1 showed Ni2+ uptake activity in a yeast expression system. These data demonstrate that AtIRT1 transports Ni2+ in roots, and strongly suggest that Ni accumulation is further accelerated by AtIRT1 that is expressed in response to excess Ni.