Jeong Sujeong, Kim Inyoung, Kim Hyun Uk
Department of Bioindustry and Bioresource Engineering Sejong University Seoul Republic of Korea.
Department of Molecular Biology Sejong University Seoul Republic of Korea.
Plant Direct. 2025 Jul 21;9(7):e70091. doi: 10.1002/pld3.70091. eCollection 2025 Jul.
The role of cytokinin among plant hormones in seed development remains largely unknown. The response regulator 21 (ARR21) is one of the cytokinin response regulators and a Type-B ARR with a nuclear localization signal and a GARP motif similar to the MYB-like DNA-binding domain. ARR21-sGreen fluorescent protein (GFP) signals were localized within the nucleus, and showed the highest expression levels in developing seeds. In addition, histochemical analysis revealed expression in the silique coats, chalazal seed coat, chalazal endosperm, and throughout the developing seed at 6 days after pollination. Two independent mutants were generated using the CRISPR/Cas9 system: (51 bp in-frame deletion) and (2 bp insertion). The seed size and weight of the mutants decreased by an average of 10.7% and 37%, respectively, compared to the wild-type (WT). In mutants, the cotyledon length of embryos and the size of seed coat cells were reduced. Seed-specific overexpression of in restored the seed length to WT levels. This study suggests that ARR21 regulates seed size by functioning in the chalazal endosperm and embryo, thereby providing insights into the role of cytokinin in seed development.
细胞分裂素在植物激素中对种子发育的作用在很大程度上仍不清楚。应答调节因子21（ARR21）是细胞分裂素应答调节因子之一，是一种B型ARR，具有核定位信号和与MYB样DNA结合域相似的GARP基序。ARR21-s绿色荧光蛋白（GFP）信号定位于细胞核内，且在发育中的种子中表达水平最高。此外，组织化学分析显示在授粉后6天，在角果果皮、合点端种皮、合点端胚乳以及整个发育中的种子中均有表达。使用CRISPR/Cas9系统产生了两个独立的突变体：（51bp框内缺失）和（2bp插入）。与野生型（WT）相比，突变体的种子大小和重量分别平均下降了10.7%和37%。在突变体中，胚的子叶长度和种皮细胞大小减小。在中种子特异性过表达可使种子长度恢复到野生型水平。这项研究表明，ARR21通过在合点端胚乳和胚中发挥作用来调节种子大小，从而为细胞分裂素在种子发育中的作用提供了见解。
