Lack of ACTPK1, an STY kinase, enhances ammonium uptake and use, and promotes growth of rice seedlings under sufficient external ammonium

Marcel P. Beier, Mitsuhiro Obara, Akiko Taniai, Yuki Sawa, Jin Ishizawa, Haruki Yoshida, Narumi Tomita, Tsuyoshi Yamanaka, Yawara Ishizuka, Syuko Kudo, Akira Yoshinari, Shiho Takeuchi, Soichi Kojima, Tomoyuki Yamaya, Toshihiko Hayakawa

研究成果: Article査読

15 被引用数 (Scopus)

抄録

Ammonium influx into plant roots via the high-affinity transport system (HATS) is down-modulated under elevated external ammonium, preventing ammonium toxicity. In ammonium-fed Arabidopsis, ammonium transporter 1 (AMT1) trimers responsible for HATS activity are allosterically inactivated in a dose-dependent manner via phosphorylation of the conserved threonine at the carboxyl-tail by the calcineurin B-like protein 1-calcineurin B-like protein-interacting protein kinase 23 complex and other yet unidentified protein kinases. Using transcriptome and reverse genetics in ammonium-preferring rice, we revealed the role of the serine/threonine/tyrosine protein kinase gene OsACTPK1 in down-modulation of HATS under sufficient ammonium. In wild-type roots, ACTPK1 mRNA and protein accumulated dose-dependently under sufficient ammonium. To determine the function of ACTPK1, two independent mutants lacking ACTPK1 were produced by retrotransposon Tos17 insertion. Compared with segregants lacking insertions, the two mutants showed decreased root growth and increased shoot growth under 1 mm ammonium due to enhanced ammonium acquisition, via aberrantly high HATS activity, and use. Furthermore, introduction of OsACTPK1 cDNA fused to the synthetic green fluorescence protein under its own promoter complemented growth and the HATS influx, and suggested plasma membrane localization. Root cellular expression of OsACTPK1 also overlapped with that of ammonium-induced OsAMT1;1 and OsAMT1;2. Meanwhile, threonine-phosphorylated AMT1 levels were substantially decreased in roots of ACTPK1-deficient mutants grown under sufficient ammonium. Bimolecular fluorescence complementation assay further confirmed interaction between ACTPK1 and AMT1;2 at the cell plasma membrane. Overall, these findings suggest that ACTPK1 directly phosphorylates and inactivates AMT1;2 in rice seedling roots under sufficient ammonium.

本文言語English
ページ(範囲)992-1006
ページ数15
ジャーナルPlant Journal
93
6
DOI
出版ステータスPublished - 2018 3

ASJC Scopus subject areas

  • 遺伝学
  • 植物科学
  • 細胞生物学

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