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HSP101-encoding NEO-TETRAPLOID RICE FERTILITY GENE 1 regulates tapetum development through interaction with SAPK2 in polyploid rice

Lichong Cao1,2,3†, Weicong Huang1,2,3†, Hang Yu1,2,3,4, Sanglin Liu1,2,3, Jianmin Yin1,2,3, Zijun Lu1,2,3, Jinwen Wu1,2,3 and Xiangdong Liu1,2,3*   

  1. 1. State Key Laboratory for Conservation and Utilization of Subtropical Agro‐Bioresources, Guangdong Laboratory for Lingnan ModernAgriculture, South China Agricultural University, Guangzhou 510642, China

    2. Guangdong Provincial Key Laboratory of Plant Molecular Breeding, Guangdong Base Bank for Lingnan Rice Germplasm Resources,College of Agriculture, South China Agricultural University, Guangzhou 510642, China

    3. Key Laboratory for Enhancing Resource Use Efficiency of Crops in South China, Ministry of Agriculture and Rural Affairs, Guangzhou510642, China

    4. Rice Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China

    †These authors contributed equally to this work.

    *Correspondence: Xiangdong Liu (xdliu@scau.edu.cn)

  • Received:2025-07-20 Accepted:2026-02-19 Online:2026-03-11
  • Supported by:
    This work was supported by the National Key R&D Program of China(2023YFD1200802), the National Natural Science Foundation of China (32572292), the Laboratory of Lingnan Modern Agriculture Project (NT2021001), and the Base Bank of Lingnan Rice Germplasm Resources Project (2024B1212060009).

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Abstract: A novel allelic variant of the heat shock protein 101, designated neo-tetraploid rice fertility gene 1 (NTRF1), has been identified and is implicated in regulating fertility in neo-tetraploid rice (NTR); however, its regulatory mechanism remains unclear. In this study, we identified the ntrf1 mutant and demonstrated that its significantly reduced seed-setting rate was due to pollen developmental defects. Mechanistically, NTRF1 deficiency disrupts reactive oxygen species (ROS) homeostasis in anthers, thereby delaying the progression of programmed cell death (PCD) in tapetal cells. RNA-seq analysis of mutant anthers revealed dysregulated expression of abscisic acid (ABA) signaling components (OsPP2C49, OsbZIP23) and ROS-related genes (OsRBOH1, OsRBOH8), along with a significant downregulation of key tapetal developmental regulators (OsGAmyb, CYP703A3). Integrated multi-omics analysis showed that the reduced pollen viability in the ntrf1 mutant is associated with the pyruvate metabolic pathway. Protein interaction assays confirmed that NTRF1 directly binds SAPK2, a core kinase in ABA signaling transduction. This interaction explained how exogenous ABA application partially restored the reduced seed-setting rate in ntrf1 mutants. Collectively, our findings elucidated an NTRF1-centered regulatory network that coordinates ABA signaling with ROS homeostasis to ensure timely tapetal PCD and subsequent pollen maturation. This study provides valuable molecular targets for advancing the genetic improvement of polyploid rice.

Key words: abscisic acid, neo-tetraploid rice, NTRF1, pollen development, programmed cell death, reactive oxygen species, rice(Oryza sativa L.)

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