Koyama Takuya, Murakami Shun, Karasawa Toshihiko, Ejiri Masato, Shiono Katsuhiro
School of Agriculture, Utsunomiya University, 350 Mine-machi, Utsunomiya, Tochigi, 321-8505, Japan.
Central Region Agricultural Research Center (Kanto, Tokai and Hokuriku Regions), National Agriculture and Food Research Organization (NARO), 2-1-18 Kannondai, Tsukuba, 305-8666, Japan.
Plant Methods. 2021 Sep 20;17(1):97. doi: 10.1186/s13007-021-00798-3.
Detailed datasets containing root system and its architecture in soil are required to improve understanding of resource capture by roots. However, most of the root study methods have paid little attention to make and preserve whole root specimens. This study introduces root system sampling equipment that makes the entire root specimen with minimum impairment and without displacement of the spatial arrangement of the root system in root boxes. The objectives are to assess: whether the equipment can rapidly sample the entire root system; whether root surface area is measurable from a scanned digital image of the root specimen; and whether staining of the entire root specimens would provide multidimensional visual information on the interaction between soil and physiological function of root system architecture (RSA). For validation, we examined the root response of two soybean cultivars to arbuscular mycorrhizal (AM) inoculation and the effect of waterlogging stress on the physiological activity of buckwheat RSA.
The root boxes allowed soybean and buckwheat plants to grow uniformly across the replications. Both species showed significant differences between cultivars and/or among treatments in shoot and root traits. The equipment enabled to sample the whole-root specimens of soybean and buckwheat, where the tips of the fine roots were alive (diameter < 0.2 mm). Also, the whole root specimens of soybean were made in about 7 min. The root surface area calculated from the scanned soybean specimens showed a significant correlation with that calculated from the roots spread out in water (a common method). Staining of the soybean root specimens enabled us to observe the localized root proliferation induced by AM colonization. Moreover, staining of the buckwheat root specimens made it possible to examine the respiratory activity of each root at different depths.
The present method realized: fast and accurate production of the whole root specimen and precise calculation of the specimens' root surface area. Moreover, staining of the root specimens enabled analyzing the interaction between soil and physiological function of RSA. The evaluation of root traits, using our methods, will contribute to developing agronomic management and breeding program for sustainable food production.
为了更好地理解根系对资源的获取，需要包含土壤中根系及其结构的详细数据集。然而，大多数根系研究方法很少关注制作和保存完整的根系标本。本研究介绍了一种根系采样设备，该设备能以最小的损伤制作完整的根系标本，且不会改变根箱中根系的空间排列。其目的是评估：该设备能否快速采集整个根系；能否从扫描的根系标本数字图像中测量根表面积；对整个根系标本进行染色是否能提供关于土壤与根系结构生理功能（RSA）相互作用的多维度视觉信息。为了验证，我们研究了两个大豆品种对丛枝菌根（AM）接种的根系反应以及渍水胁迫对荞麦RSA生理活性的影响。
根箱使大豆和荞麦植株在各重复间均匀生长。两个物种在地上部和根系性状的品种间和/或处理间均表现出显著差异。该设备能够采集大豆和荞麦的完整根系标本，其中细根（直径<0.2毫米）的根尖是活的。此外，大豆的完整根系标本制作时间约为7分钟。从扫描的大豆标本计算得到的根表面积与用水展开根系（一种常用方法）计算得到的根表面积显著相关。对大豆根系标本进行染色使我们能够观察到AM定殖诱导的局部根系增殖。此外，对荞麦根系标本进行染色使得能够检测不同深度各根系的呼吸活性。
本方法实现了：快速准确地制作完整根系标本并精确计算标本的根表面积。此外，对根系标本进行染色能够分析土壤与RSA生理功能之间的相互作用。使用我们的方法评估根系性状将有助于制定可持续粮食生产的农艺管理和育种计划。
