Functional analysis of the <i>GmESR1</i> gene associated with soybean regeneration

Plant regeneration can occur via in vitro tissue culture through somatic embryogenesis or de novo shoot organogenesis. Transformation of soybean (Glycine max) is difficult, hence optimization of the transformation system for soybean regeneration is required. This study investigated ENHANCER OF SHOOT REGENERATION 1 (GmESR1), a soybean transcription factor that targets regeneration-associated genes. Sequence analysis showed that GmESR1 contained a conserved 57 amino acid APETALA 2 (AP2)/ETHYLENE RESPONSE FACTOR (ERF) DNA-binding domain. The relative expression level of GmESR1 was highest in young embryos, flowers and stems in the soybean cultivar ‘Dongnong 50’. To examine the function of GmESR1, transgenic Arabidopsis (Arabidopsis thaliana) and soybean plants overexpressing GmESR1 were generated. In Arabidopsis, overexpression of GmESR1 resulted in accelerated seed germination, and seedling shoot and root elongation. In soybean overexpression of GmESR1 also led to faster seed germination, and shoot and root elongation. GmESR1 specifically bound to the GCC-box. The results provide a foundation for the establishment of an efficient and stable transformation system for soybean.植物再生可通过体外组织培养途径，经体细胞胚胎发生或从头芽器官发生实现。大豆（Glycine max）的遗传转化难度较高，因此亟需优化用于大豆再生的转化体系。本研究针对大豆中一类靶向再生相关基因的转录因子——芽再生增强因子1（ENHANCER OF SHOOT REGENERATION 1，GmESR1）展开探究。序列分析结果显示，GmESR1含有一个保守的57个氨基酸组成的APETALA 2（AP2）/乙烯响应因子（ETHYLENE RESPONSE FACTOR，ERF）类DNA结合结构域。在大豆品种‘东农50’中，GmESR1的相对表达水平在幼胚、花和茎中最高。为探究GmESR1的功能，本研究构建了过表达GmESR1的转基因拟南芥（Arabidopsis thaliana）与大豆植株。在拟南芥中，过表达GmESR1可加速种子萌发，并促进幼苗地上部与根系的伸长生长。在大豆中，过表达GmESR1同样可加快种子萌发，并促进地上部与根系的伸长。GmESR1可特异性结合GCC盒（GCC-box）。本研究结果为构建高效且稳定的大豆遗传转化体系奠定了基础。