Targeted regulation using transgrafting technology has been becoming a trend. However, the mechanisms of transgene-derived signal communication between rootstocks and scions remain unclear in woody plants. Here, we grafted wild type (WT) walnut (Juglans regia L.) on WT (WT/WT), JrGA20ox1 (encodes a gibberellin 20-oxidase) overexpressed (WT/OE) and JrGA20ox1-RNAi transformation (WT/RNAi) walnut in vitro, respectively. We aimed to elucidate the mechanisms of JrGA20ox1-derived signal communication under PEG simulated drought stress between rootstocks and scions in walnut. We demonstrated that JrGA20ox1-OE and JrGA20ox1-RNAi rootstocks could transport active GAs and JrGA20ox1-RNAi vector produced sRNAs to WT scions under PEG simulated drought stress, respectively. The movement of sRNAs further led to a decline in JrGA20ox1 expression and active GA content successively. Meanwhile, the unknown signals may mobile between rootstocks and scions. The mobile signals reduced the expression of a series of GA-responsive and GA-nonresponsive genes, and induced ROS production in guard cells and the increase of ABA content, which may be contributed to the drought tolerance of WT/RNAi, while WT/OE is in an opposite manner. The findings suggest that JrGA20ox1 derived rootstock-to-scion movement of signals are involved in drought tolerance of scions. Our research will provide a feasible approach for studying signal communication in woody plants.

中文翻译：

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JrGA20ox1 转化砧木向嫁接核桃中的野生型接穗传递干旱响应信号


利用移植技术进行针对性监管已成为趋势。然而，木本植物中砧木和接穗之间转基因衍生的信号通讯机制仍不清楚。在这里，我们将野生型（WT）核桃（Juglans regia L.）嫁接到WT（WT/WT）、JrGA20ox1（编码赤霉素20-氧化酶）过表达（WT/OE）和JrGA20ox1-RNAi转化（WT/RNAi）核桃上分别在体外。我们的目的是阐明 PEG 模拟干旱胁迫下核桃砧木和接穗之间源自 JrGA20ox1 的信号通信机制。我们证明，在 PEG 模拟干旱胁迫下，JrGA20ox1-OE 和 JrGA20ox1-RNAi 砧木可以分别将活性 GA 和 JrGA20ox1-RNAi 载体产生的 sRNA 转运至 WT 接穗。 sRNA的移动进一步导致JrGA20ox1表达和活性GA含量相继下降。同时，未知信号可能在砧木和接穗之间移动。移动信号降低了一系列GA响应和GA非响应基因的表达，并诱导保卫细胞中ROS的产生和ABA含量的增加，这可能有助于WT/RNAi的耐旱性，而WT/OE是相反的方式。研究结果表明，JrGA20ox1 衍生的砧木到接穗的信号运动与接穗的耐旱性有关。我们的研究将为研究木本植物信号通信提供可行的方法。