How plants halt growth of their root hairs

February 14, 2018

Transcription factors GTL1 and DF1 act as brakes on length

Root hairs are cells present on the surface of plant roots that serve to efficiently absorb water and nutrients from soila. Plants adjust the amounts of nutrients they absorb from the surrounding soil by controlling root hair length, making root hair growth control an important mechanism for plant growth in a variety of environments. However, the detailed molecular mechanism controlling root hair growth remained unclear.

International joint research by RIKEN CSRS, North Carolina State University, Tokyo University of Science, the Salk Institute for Biological Studies and Duke University has identified transcription factors that control root hair length. Using Arabidopsis thaliana as a model plant, the group determined that transcription factor GTL1 is responsible for suppressing root hair growth. To clarify the mechanism, researchers investigated genes which aredifferentially expressed in the gtl1 df1 double mutant with long root hairs and the GTL1 overexpression line with short root hairs. They found that the ROOT HAIR_DEFECTIVE_SIX-LIKE_4 (RSL4) gene is suppressed by GTL1 and its homolog DF1.

By combination of comprehensive gene expression analysis and chromatin immunoprecipitation analysis, the researchers found out that RSL4 promotes expression of GTL1 and that RSL4 and GTL1 share common targets, with RSL4 acting as a promoter and GTL1 functioning as an inhibitor—the two work together like an accelerator and brake to properly control the growth of root hairs.

Engineering of the GTL1 functions is expected to lead to practical applications such as the development of plants capable of growing under severe conditions.

Original article
Development doi:10.1242/dev.159707
M. Shibata, C. Breuer, A. Kawamura, N. M Clark, B. Rymen, L. Braidwood, K. Morohashi, W. Busch, P. N Benfey, R. Sozzani, K. Sugimoto,
"GTL1 and DF1 regulate root hair growth through transcriptional repression of ROOT HAIR DEFECTIVE 6-LIKE 4 in Arabidopsis".
Keiko Sugimoto; Team Leader
Michitaro Shibata; Visiting Researcher
Cell Function Research Team