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Uneven hormone distribution in plants regulates cell division and growth, biologists discover

New research from an international team of plant biologists, led by researchers at the VIB-UGent Center for Plant Systems Biology, has revealed crucial insights into the role brassinosteroids—essential plant hormones—play in regulating cell division and growth. The findings, in Cell, provide a comprehensive understanding of how these hormones influence development at the cellular level.

Brassinosteroids are vital hormones for plants, which influence their growth and development at the cellular level. Understanding the dynamics of brassinosteroid signaling helps us grasp how plants grow, adapt to their surroundings, and manage resources effectively. This knowledge could pave the way for improving crop growth and resilience in a rapidly changing environment.

New research led by Prof. Jenny Russinova (VIB-UGent) in close collaboration with late Philip Benfey's lab (Duke University) and later work led by Prof. Trevor Nolan (California Institute of Technology) explores the dynamics of key brassinosteroid signaling components in the root meristem. The study reveals that following symmetric anticlinal divisions, these components are distributed unevenly, leading to the preferential expression of brassinosteroid biosynthetic enzymes in the lower daughter cell post-division. This asymmetric hormonal signaling is essential for root growth and development in plants.

"We found," says Dr. Nemanja Vukašinović, co-first author of the study, "that during cell division, brassinosteroids are distributed unevenly between the new cells formed. This means that one cell receives a boost in hormone activity, while the other supports the production of the hormones."

Tracking plant hormones

Using an innovative combination of single-cell RNA sequencing and long-term live-cell imaging, the team traced fluctuations in brassinosteroid signaling across different phases of the cell cycle. They discovered that signaling peaks during the G1 phase and diminishes during mitosis, highlighting a crucial time window for hormonal action in plant cell development. This phase-dependent regulation may influence how plants adapt to their environment and optimize their growth.

"Understanding how brassinosteroid signaling operates in relation to the cell cycle opens new avenues to manipulate plant growth and development," said Prof. Russinova. "Our research not only sheds light on fundamental biological processes but also sets the stage for biotechnological applications in crop improvement."

The study also raises important questions about the mechanisms regulating this uneven distribution and its consequences for overall plant health and functioning. That knowledge, in turn, holds promise for future agricultural strategies, especially as global food demands increase.