Molecular mechanism to prevent excessive uptake of an ammonium nutrient into rice roots

2020 Fiscal Year Final Research Report

• Project/Area Number: 17H03780
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Plant nutrition/Soil science
• Research Institution: Tohoku University
• Principal Investigator: HAYAKAWA Toshihiko 東北大学, 農学研究科, 准教授 (60261492)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: 植物代謝調節 / 植物栄養学 / 遺伝子 / 酵素 / シグナル伝達

Outline of Final Research Achievements

Nitrogen is a major limiting nutrient in plant growth and productivity. In flooded paddy soils, wetland rice, an important mainstay crop, preferentially takes up ammonium as an abundant inorganic nitrogen source. However, an ammonium supply at high concentration is frequently toxic to many terrestrial plants. Therefore, ammonium influx into plant roots via the high-affinity transport system (HATS) is down-modulated under elevated external ammonium. HATS-responsible, plasma membrane-located ammonium transporter 1 (AMT1) proteins are inactivated via phosphorylation of the conserved threonine residue at the cytoplasmic carboxyl-tail under elevated external ammonium. We identified the role of a protein kinase, ACTPK1, in phosphorylation and inactivation of ammonium-induced AMT1;2 in ammonium-preferring rice grown under sufficient ammonium. This finding will help to improve nitrogen use efficiency in rice and confer ammonium-resistance on ammonium-sensitive plants.

Free Research Field

植物栄養学・土壌学

Academic Significance and Societal Importance of the Research Achievements

近年、アンモニウム感受性かつモデル植物のシロイヌナズナの根のアンモニウム吸収を負に制御するCBL1/CIPK23が報告された[Straub et al. (2017) Plant Cell 29:409-422]が、本研究では、世界に先駆けて好アンモニウム性かつ世界人口の半数以上が主食とする作物のイネの根のアンモニウム吸収を負に制御するACTPK1を同定した[Beier et al. (2018) Plant J. 93: 992-1006] 。本研究成果は、好アンモニウム性作物であるイネのアンモニウム利用の効率化やアンモニウム感受性植物への耐性付与などの分子育種につながると期待される。