Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
Plant J. 2020 Jul;103(2):918-929. doi: 10.1111/tpj.14768. Epub 2020 Apr 28.
Grafting techniques have been applied in studies of systemic, long-distance signaling in several model plants. Seedling grafting in Arabidopsis, known as micrografting, enables investigation of the molecular mechanisms of systemic signaling between shoots and roots. However, conventional micrografting requires a high level of skill, limiting its use. Thus, an easier user-friendly method is needed. Here, we developed a silicone microscaled device, the micrografting chip, to obviate the need for training and to generate less stressed and more uniformly grafted seedlings. The chip has tandemly arrayed units, each of which consists of a seed pocket for seed germination and a micro-path with pairs of pillars for hypocotyl holding. Grafting, including seed germination, micrografting manipulation and establishment of tissue reunion, is performed on the chip. Using the micrografting chip, we evaluated the effect of temperature and the carbon source on grafting, and showed that a temperature of 27°C and a sucrose concentration of 0.5% were optimal. We also used the chip to investigate the mechanism of systemic signaling of iron status using a quadruple nicotianamine synthase (nas) mutant. The constitutive iron-deficiency response in the nas mutant because of iron accumulation in shoots was significantly rescued by grafting of wild-type shoots or roots, suggesting that shoot- and root-ward translocation of nicotianamine-iron complexes and/or nicotianamine is essential for iron mobilization. Thus, our micrografting chip will promote studies of long-distance signaling in plants.
嫁接技术已被应用于几种模式植物的系统、长距离信号转导研究中。拟南芥的幼苗嫁接，称为微嫁接，可用于研究地上部和地下部之间系统信号的分子机制。然而，传统的微嫁接需要高水平的技能，限制了它的使用。因此，需要一种更简单、更易用的方法。在这里，我们开发了一种硅微尺度装置，即微嫁接芯片，以避免培训的需要，并产生压力较小且嫁接幼苗更均匀的效果。该芯片具有串联排列的单元，每个单元都有一个用于种子发芽的种子口袋和一个带有一对支柱的微通道，用于固定下胚轴。嫁接，包括种子发芽、微嫁接操作和组织愈合的建立，都在芯片上进行。使用微嫁接芯片，我们评估了温度和碳源对嫁接的影响，结果表明 27°C 的温度和 0.5%的蔗糖浓度是最佳的。我们还使用该芯片研究了铁营养状况的系统信号转导机制，利用四重烟酰胺合成酶（nas）突变体。由于铁在地上部的积累，nas 突变体表现出组成型缺铁反应，通过嫁接野生型地上部或地下部可以显著挽救，这表明烟酰胺-铁复合物和/或烟酰胺的地上部和地下部的转运对于铁的动员是必需的。因此，我们的微嫁接芯片将促进植物长距离信号转导的研究。
