Investigation of <i>Arabidopsis</i> root skototropism with different distance settings

Plants can activate protective and defense mechanisms under biotic and abiotic stresses. Their roots naturally grow in the soil, but when they encounter sunlight in the top-soil layers, they may move away from the light source to seek darkness. Here we investigate the skototropic behavior of roots, which promotes their fitness and survival. Glutamate-like receptors (GLRs) of plants play roles in sensing and responding to signals, but their role in root skototropism is not yet understood. Light-induced tropisms are known to be affected by auxin distribution, mainly determined by auxin efflux proteins (PIN proteins) at the root tip. However, the role of PIN proteins in root skototropism has not been investigated yet. To better understand root skototropism and its connection to the distance between roots and light, we established five distance settings between seedlings and darkness to investigate the variations in root bending tendencies. We compared differences in root skototropic behavior across different expression lines of <i>Arabidopsis thaliana</i> seedlings (<i>atglr3.7 ko, AtGLR3.7 OE</i>, and <i>pin2 knockout</i>) to comprehend their functions. Our research shows that as the distance between roots and darkness increases, the root’s positive skototropism noticeably weakens. Our findings highlight the involvement of GLR3.7 and PIN2 in root skototropism.植物在生物胁迫与非生物胁迫条件下，可激活保护性与防御性机制。植物根系天然生长于土壤中，但当在土层表层接触到光照时，它们会背离光源移动以寻求黑暗环境。本研究聚焦于可提升植物适应性与存活能力的根系向暗性运动。植物的谷氨酸类受体（Glutamate-like receptors, GLRs）参与信号感知与响应过程，但目前尚不明确其在根系向暗性运动中发挥的作用。已知光诱导的向性运动受生长素分布调控，而生长素分布主要由根尖的生长素输出蛋白（PIN proteins）决定。然而，目前尚未探究PIN蛋白在根系向暗性运动中的功能。为更深入地解析根系向暗性运动及其与根系-光照间距的关联，本研究设置了5组幼苗与黑暗环境的间距梯度，以探究根系弯曲倾向的变化规律。本研究以不同遗传背景的拟南芥（Arabidopsis thaliana）幼苗（包括atglr3.7敲除株系、AtGLR3.7过表达株系以及pin2敲除株系）为材料，对比其根系向暗性运动的差异，以明确相关基因的功能。研究结果表明，随着根系与黑暗环境的间距增大，根系的正向向暗性显著减弱。本研究结果证实，GLR3.7与PIN2蛋白参与调控根系向暗性运动。