J Integr Plant Biol.

• Research Articles •    

Novel Wx alleles generated by base editing for improvement of rice grain quality

Xiaorui Huang1,2†, Fei Su1,2†, Sheng Huang1,2, Fating Mei2, Xiaomu Niu2, Changle Ma1, Hui Zhang3, Xiaoguo Zhu3, Jian-Kang Zhu4, Jinshan Zhang1,2*   

  1. 1School of Life Sciences, Shandong Normal University, Ji’nan 250014, China
    2Bellagen Biotechnology Co. Ltd., Ji’nan 250000, China
    3College of Life Science, Shanghai Normal University, Shanghai 200234, China
    4Shanghai Center for Plant Stress Biology and Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 201602, China

    These authors contributed equally.
    *Correspondence: zhangjinshan@bellagen.cn
  • Received:2021-02-09 Accepted:2021-04-12 Online:2021-04-13

Abstract: Amylose content (AC), which is regulated by the Waxy (Wx) gene, is a major indicator of eating and cooking quality (ECQ) in rice (Oryza sativa). Thus far, only a limited number of mutations in the N-terminal domain of Wx were found to have a major impact on the AC of rice grains and no mutations with such effects were reported for other regions of the Wx protein. Here, nucleotide substitutions in the middle region of Wx were generated by adenine and cytosine base editors. The nucleotide substitutions led to changes in 15 amino acid residues of Wx, and a series of novel Wx alleles with ACs of 0.3%–29.43% (wild type with AC of 19.87%) were obtained. Importantly, the waxyabe2 allele showed a “soft rice” AC, improved ECQ, favorable appearance, and no undesirable agronomic traits. The transgenes were removed from the waxyabe2 progeny, generating a promising breeding material for improving rice grain quality.

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