Hormone crosstalk orchestrates root development

Qin et al. identify a mechanism by which ethylene activates gibberellin catabolism to determine primary root growth in rice.

Hua Qin and Rongfeng Huang

Biotechnology Research Institute, Chinese Academy of Agricultural Sciences

Background: The optimization of root architecture is one of the most effective ways to improve crop productivity and stress resistance. The primary root, which emerges when the seed germinates, is critical for plant establishment and survival, providing the seedling with its sole source of anchorage and water/nutrient absorption. In rice, the primary root ceases to grow after 7–10 days of rapid growth; however, the underlying mechanism determining primary root growth is largely unclear.

Question: We wanted to know whether ethylene and gibberellin are involved in primary root development in young rice seedlings. What is the crosstalk node between ethylene and gibberellin in primary root growth?

We show that gibberellins and ethylene successively steer primary root elongation and the subsequent cessation of primary root growth in young rice seedlings. The ethylene signaling transcription factor ETHYLENE INSENSITIVE3-LIKE 1 (OsEIL1) promotes the expression of gibberellin metabolism genes OsGA2ox1, OsGA2ox2, OsGA2ox3, and OsGA2ox5, resulting in the deactivation of gibberellin, which further inhibits cell proliferation in root meristems, and the cessation of primary root growth. Our results shed light on the molecular mechanism of ethylene action during primary root elongation in young rice seedlings, providing insight into the coordination of ethylene and gibberellin during root development and seedling establishment.

Next steps: We aim to improve crop yields by improving their root systems. Further study will focus on how plants perceive external changes and translate cues into adaptive responses by modulating endogenous hormone crosstalk dynamics.

Hua Qin, Bipin K. Pandey, Yuxiang Li, Guoqiang Huang, Juan Wang, Ruidang Quan, Jiahao Zhou, Yun Zhou, Yuchen Miao, Dabing Zhang, Malcolm J. Bennett, and Rongfeng Huang. (2022). Orchestration of ethylene and gibberellin signals determines primary root elongation in rice. Plant Cell.