Aims

Laser micromanipulation such as dissection or optical trapping enables remote physical modification of the activity of tissues, cells and organelles. To date, applications of laser manipulation to plant roots grown in soil have been limited. Here, we show laser manipulation can be applied in situ when plant roots are grown in transparent soil.

Methods

We have developed a Q-switched laser manipulation and imaging instrument to perform controlled dissection of roots and to study light-induced root growth responses. We performed a detailed characterisation of the properties of the cutting beams through the soil, studying dissection and optical ablation. Furthermore, we also studied the use of low light doses to control the root elongation rate of lettuce seedlings (Lactuca sativa) in air, agar, gel and transparent soil.

Results

We show that whilst soil inhomogeneities affect the thickness and circularity of the beam, those distortions are not inherently limiting. The ability to induce changes in root elongation or complete dissection of microscopic regions of the root is robust to substrate heterogeneity and microscopy set up and is maintained following the limited distortions induced by the transparent soil environment.

Conclusions

Our findings show that controlled in situ laser dissection of root tissues is possible with a simple and low-cost optical set-up. We also show that, in the absence of dissection, a reduced laser light power density can provide reversible control of root growth, achieving a precise “point and shoot” method for root manipulation.

中文翻译：

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透明土壤中根组织的原位激光处理

目标

激光显微操作，如解剖或光学捕获，可以远程物理修改组织、细胞和细胞器的活动。迄今为止，激光操纵在土壤中生长的植物根部的应用受到限制。在这里，我们展示了当植物根系在透明土壤中生长时可以原位应用激光操作。

方法

我们开发了一种 Q 开关激光操作和成像仪器，用于对根进行受控解剖并研究光诱导的根生长反应。我们对穿过土壤的切割光束的特性进行了详细的表征，研究了解剖和光学烧蚀。此外，我们还研究了在空气、琼脂、凝胶和透明土壤中使用低光剂量控制莴苣幼苗（ Lactuca sativa ）的根系伸长率。

结果

我们表明，虽然土壤的不均匀性会影响梁的厚度和圆度，但这些变形并不是固有的限制。诱导根伸长变化或根部微观区域完全解剖的能力对于基质异质性和显微镜设置是稳健的，并且在透明土壤环境引起的有限变形后保持不变。

结论

我们的研究结果表明，通过简单且低成本的光学设置，可以对根组织进行受控的原位激光解剖。我们还表明，在没有解剖的情况下，降低激光功率密度可以提供对根部生长的可逆控制，从而实现精确的“点对点”根部操作方法。