State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Maize Research Institute, Sichuan Agricultural University, Chengdu, 611130, China.
Plant J. 2022 Feb;109(4):980-991. doi: 10.1111/tpj.15609. Epub 2021 Dec 12.
The ability of immature maize (Zea mays) embryos to form embryonic calluses (ECs) is highly genotype dependent, which limits transgenic breeding development in maize. Here, we report the association map-based cloning of ZmSAUR15 using an association panel (AP) consisting of 309 inbred lines with diverse formation abilities for ECs. We demonstrated that ZmSAUR15, which encodes a small auxin-upregulated RNA, acts as a negative effector in maize EC induction. Polymorphisms in the ZmSAUR15 promoter that influence the expression of ZmSAUR15 transcripts modulate the EC induction capacity in maize. ZmSAUR15 is involved in indole-3-acetic acid biosynthesis and cell division in immature embryo-derived callus. The ability of immature embryos to induce EC formation can be improved by the knockout of ZmSAUR15, which consequently increases the callus regeneration efficiency. Our study provides new insights into overcoming the genotypic limitations associated with EC formation and improving genetic transformation in maize.
未成熟玉米（Zea mays）胚胎形成胚胎愈伤组织（ECs）的能力高度依赖于基因型，这限制了玉米的转基因育种发展。在这里，我们使用由 309 个具有不同 EC 形成能力的自交系组成的关联小组（AP），报告了基于关联图谱的 ZmSAUR15 的克隆。我们证明，编码小生长素上调 RNA 的 ZmSAUR15 作为玉米 EC 诱导的负效应物发挥作用。影响 ZmSAUR15 转录物表达的ZmSAUR15 启动子中的多态性调节玉米中 EC 诱导能力。ZmSAUR15 参与吲哚-3-乙酸生物合成和未成熟胚衍生愈伤组织中的细胞分裂。通过敲除ZmSAUR15 可以提高 EC 形成能力，从而提高愈伤组织再生效率。我们的研究为克服与 EC 形成相关的基因型限制和提高玉米遗传转化提供了新的见解。
