J Integr Plant Biol

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  • 收稿日期:2025-09-15 接受日期:2026-01-23

OsSIZ1 regulates rice nitrogen-use efficiency and grain yield by modulating auxin levels

Bingyu Jiang1†, Yunzhi Huang1†, Siyu Zhang1, Ying Yu1, Shunqi Li1, Chengbo Shen1,nYaojun Qin1, Menghan Huang1, Shuming Kang1, Zulong Mo1, Jiayi Xu1, Yue Li1, Yajing Song1, Yanan Tian1 and Shan Li1,2*   

  1. 1. State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 211800, China

    2. Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing 211800, China

    †These authors contributed equally to this work.

    *Correspondence: Shan Li (shanli@njau.edu.cn)

  • Received:2025-09-15 Accepted:2026-01-23
  • Supported by:
    This project was supported by grants from National Natural Science Foundation of China (Nos. 32441056 and 32372121to Shan Li; No. 32401866 to S.Z.), Scienti?c Research Innovation Capability Support Project for Young Faculty (SRICSPYF‐ZY2025131 to Shan Li), Jiangsu Funding Program for Excellent Postdoctoral Talent (Nos. 2025ZB165 toY.H; 2024ZB460 to S.Z.), China Postdoctoral Science Foundation (Nos. GZC20252649 and 2025M773996 to Y.H.), Fundamental Research Funds for the Central Universities(QTPY2025011 to Shan Li), and Jiangsu Collaborative Innovation Center for Modern Crop Production.

Abstract: Auxin plays a pivotal role in regulating crop nitrogen (N)-use efficiency (NUE), coordinating both N-responsive root development and the expression of N metabolism genes. In our previous work, we identified DULL NITROGEN RESPONSE1 (DNR1) as a repressor within the auxin-mediated NUE network in rice. Here, we further delineate this pathway by identifying the SUMO E3 ligase OsSIZ1 as a key upstream regulator of DNR1. Contrary to its canonical role, we discovered that OsSIZ1 exhibits ubiquitin E3 ligase activity toward DNR1, facilitating its polyubiquitination at lysine 314 and subsequent degradation. This degradation promotes auxin accumulation, thereby enhancing NUE and grain yield. Notably, the yield advantage driven by OsSIZ1 is most pronounced under low-N conditions, underscoring its potential as a breeding target for developing resilient crops that require less N fertilizer, enabling a more sustainable agriculture.

Key words: auxin, DNR1, NUE, OsSIZ1, rice, ubiquitination

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