Hokkaido University Research Profiles

Japanese
Life Sciences

Controlling Plants with Roots

Masaaki Watahiki Associate Professor

How to control root regeneration

Roots are essential organs of many plants, and root injuries heal quickly. This is because a mechanism is at work that maintains the biomass ratio between the roots and the above-ground parts at a constant value. At this laboratory, we have clarified the root regeneration mechanism and have demonstrated the possibility that technology can control the biomass ratio.

Content of research

Root pruning (root cutting) has widely been used in horticulture such as bonsai and fruit tree cultivation to empirically control the above-ground parts by controlling the roots. This is a technique that empirically utilizes the fact that the biomass ratio of the roots to the above-ground parts remains constant. We have discovered YUCCA9, a gene that synthesizes auxin, a plant hormone necessary for root regeneration when roots are cut. In the course of our research, we have been able to combine drugs that pharmacologically inhibit root regeneration, and we have also been able to produce plants with genetic traits that prevent root regeneration from occurring.
Root regeneration is a widespread phenomenon of land plants, and by applying this research to cultivated varieties, it will be possible to increase or decrease the above-ground biomass, which will result in higher yields, labor intensiveness, cost control, and high added value to agricultural and horticultural crop varieties.

  • Fig. 1 Untreated Arabidopsis thaliana and Arabidopsis thaliana of which the main root was cut during the growth stage (left), and comparison of the total length of the root system 4 days after the root was cut (right). Roots regenerated to the untreated level within 4 days after the main root was cut. (The photo on the left was taken 4 days after the treatment. The red arrow indicates the position where the main root was cut.)

  • Fig. 2 The mechanism revealed with this study. Root cutting activates the YUCCA9 gene, which leads to auxin synthesis and other processes, and results in the formation and development of lateral roots. By artificially controlling this mechanism, it may be possible to regulate the growth of plants. On the other hand, we have not yet identified the signals that are triggered by root cutting to activate YUCCA9, and further studies are required.

Potential for social implementation

  • ・Genetic or chemical control of plant roots is expected to result in high yield, labor intensiveness, cost control, and high added value to agricultural and horticultural crop varieties.

Appealing points to industry and local governments

With the clarification of the molecular mechanism of the traditional “root cutting response” technique, it is now possible to artificially control the regenerative ability of plants. By controlling this mechanism pharmacologically and genetically, it will be possible to draw out the natural ability of plants when needed, and the characteristics of cultivated varieties.

2022/5/27Released