Poster Presentation International Plant Molecular Biology Conference 2024

Polycomb Repressive Complex 2 suppresses parthenogenesis and autonomous endosperm formation in rice (#140)

xiaoba Wu 1 , Liqiong Xie 2 , Xizhe Sun 3 4 , Ningning Wang 5 , Jean Finnegan 1 , Chris Helliwell 1 , Jialing Yao 6 , Hongyu Zhang 7 , Xianjun Wu 7 , Phil Hands 1 , Falong Lu 8 9 , Lisong Ma 3 4 , Bing Zhou 10 , Abed Chaudhury 11 , Xiaofeng Cao 12 13 , Ming Luo 1
  1. CSIRO, Acton, ACT, Australia
  2. Xinjiang Key Laboratory of Biological Resources and Genetic Engineering，School of Life Science and Technology, Xinjiang University, Urumqi 830046, P. R. China, Xinjiang
  3. The State Key Laboratory of North China Crop Improvement and Regulation, College of Horticulture, Hebei Agricultural University, Baoding, 071001, P. R. China, Baoding
  4. Division of Plant Science, Research School of Biology, the Australian National University, ACT 2601, Australia, Canberra
  5. Faculty of agronomy, Jilin Agricultural University, Changchun, 130118, P.R. China, Changchun
  6. College of life science and technology, Huazhong Agricultural University, Wuhan 430070, P.R. China, Wuhan
  7. State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Rice Research Institute, Sichuan Agricultural University, Chengdu, 611130, P. R. China, Chengdu
  8. State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, P. R. China., Beijing
  9. University of Chinese Academy of Sciences, Beijing 100049, P. R. China., Beijing
  10. Institute of zoology, Chinese Academy of Sciences, Beijing 100101, P.R. China, Beijing
  11. Krishan Foundation Pty Ltd, ACT 2601, Australia, Canberra
  12. State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, P. R. China, Beijing
  13. University of Chinese Academy of Sciences, Beijing, P. R. China, Beijing

Prevention of autonomous egg division before fertilization ensures successful reproduction in flowering plants. The double fertilization triggers the initiation of embryogenesis and endosperm formation. The molecular mechanism that prevents the initiation of embryo and endosperm is not well understood. Here we show in rice (Oryza sativa) that the FIS-PRC2 homologous genes rice FERTILIZATION INDEPENDENT ENDOSPERM 1 (OsFIE1) and OsFIE2 redundantly repress egg and central cell respectively from autonomous division. Ovules with the Osfie1 and Osfie2 double mutations caused parthenogenesis and autonomous endosperm formation at very high frequency, while the single Osfie2 mutation resulted in pre-embryo-like structure formation from synergids at a low frequency without fertilization. The transcriptomic results indicate that the maternal alleles of the usually paternal genome expressed pluripotency factors were activated, suggesting that the FIS-PRC2 may repress the pluripotency factors directly in egg before fertilization. Similarly, the maternal alleles of the paternally expressed imprinted genes (PEGs) were activated in the autonomous endosperm, including the conserved auxin biosynthesis imprinted gene OsYUCCA11, consistent with our ChIP assay where PRC2 modulated H3K27me3 targets the maternal alleles of PEGs in endosperm. The identification of the FIS-PRC2 function in repressing autonomous division of egg and central cell in rice shed light on how epigenetic regulation and fertilization interplay to ensure proper seed development. The function of FIS-PRC2 may be manipulated for inducing haploid for speed breeding or harnessed for engineering synthetic apomictic crops.

  1. Wu, X., Xie, L., Sun, X. et al. Mutation in Polycomb repressive complex 2 gene OsFIE2 promotes asexual embryo formation in rice. Nat. Plants 9, 1848–1861 (2023). https://doi.org/10.1038/s41477-023-01536-4