As a perennial herbaceous species, Panax ginseng is widely cultivated and used as traditional herbal medicine. The root of Panax ginseng commonly remains expensive as conventional breeding of Panax ginseng is difficult. Somatic embryogenesis (S.E.) is a useful tool for plant propagation and optimal model for understanding the mechanisms of plant embryogenesis. In Panax ginseng, increasing studies have been widely performed to optimize the technology of S.E., while the underlying mechanism remains unclear. In this paper, we cloned and identified a WRKY family gene named PgWRKY6 which is upregulated in response to 2,4-D (2,4-dichlorophenoxyacetic acid)-induced embryogenic callus development. The silencing of PgWRKY6 obviously reduces the induction rate of embryogenic callus, indicating its crucial role in S.E. of Panax ginseng hairy root. The expressions of several ROS-scavenging genes are also inducible during embryogenic callus development, and the transcriptions of PgGST, PgAPX1, and PgSOD are demonstrated to be regulated by PgWRKY6. Recombinant PgWRKY6, an approximate 40-KDa protein purified from Escherichia coli, shows a specific DNA-binding activity with a potential recognition site of TTGAC(C/T). This work demonstrated that as a conserved WRKY family transcription factor, PgWRKY6 functions upstream of PgGST, PgAPX1, and PgSOD, and potentially mediated auxins –ROS signaling pathway in the process of S.E. in Panax species.

中文翻译：

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参与人参体细胞胚胎发生的 WRKY 家族基因的功能表征

人参作为多年生草本植物，被广泛种植和用作传统草药。由于人参的常规育种很困难，人参的根通常仍然很昂贵。体细胞胚胎发生 (SE) 是植物繁殖的有用工具，也是了解植物胚胎发生机制的最佳模型。在人参中，越来越多的研究已广泛进行以优化 SE 技术，但其潜在机制尚不清楚。在本文中，我们克隆并鉴定了一个名为 PgWRKY6 的 WRKY 家族基因，该基因响应 2,4-D（2,4-二氯苯氧乙酸）诱导的胚性愈伤组织发育而上调。PgWRKY6 的沉默明显降低了胚性愈伤组织的诱导率，表明其在人参毛状根的 SE 中起关键作用。在胚性愈伤组织发育过程中，几个 ROS 清除基因的表达也是可诱导的，并且 PgGST、PgAPX1 和 PgSOD 的转录被证明受 PgWRKY6 调控。重组 PgWRKY6 是一种从大肠杆菌中纯化的大约 40 KDa 的蛋白质，显示出特定的 DNA 结合活性，具有潜在的 TTGAC(C/T) 识别位点。这项工作表明，作为一种保守的 WRKY 家族转录因子，PgWRKY6 在 PgGST、PgAPX1 和 PgSOD 的上游发挥作用，并可能在人参物种的 SE 过程中介导生长素-ROS 信号通路。一种从大肠杆菌中纯化的大约 40-KDa 蛋白质，显示出特定的 DNA 结合活性，具有潜在的 TTGAC(C/T) 识别位点。这项工作表明，作为一种保守的 WRKY 家族转录因子，PgWRKY6 在 PgGST、PgAPX1 和 PgSOD 的上游发挥作用，并可能在人参物种的 SE 过程中介导生长素-ROS 信号通路。一种从大肠杆菌中纯化的大约 40-KDa 蛋白质，显示出特定的 DNA 结合活性，具有潜在的 TTGAC(C/T) 识别位点。这项工作表明，作为一种保守的 WRKY 家族转录因子，PgWRKY6 在 PgGST、PgAPX1 和 PgSOD 的上游发挥作用，并可能在人参物种的 SE 过程中介导生长素-ROS 信号通路。