Scientists identify a hormone that coordinates plant regeneration

Experts at the Institute of Science and Technology Austria have identified the mechanisms that regulate plant regeneration. The study revealed that the hormone Auxin, along with pressure changes that take place upon injury, precisely coordinate the roles of plant cells in healing wounds. 

Animals and humans have cells that are specialized to seek out and heal wounds. However, the targeted migration of cells is not possible in plants because plant cells are immobile.

In plant regeneration, the cells that are adjacent to a wound will either divide or grow to fill the gaps caused by injury. This process is extremely precise, as each individual cell must decide whether it will stretch or multiply to contribute to filling the wound.

Despite the fact that plant regeneration has been studied since the mid-1800s, the reasoning behind each cell’s decision on how to best tend to a wound has remained a mystery. 

A team of scientists led by Professor Jiří Friml has discovered that the role of individual plant cells during regeneration is regulated by the hormone Auxin. The cells are also guided by changes in pressure that take place within the plant after injury.  

“It is incredibly fascinating how robust and flexible plant regeneration is, considering how static those organisms are,” said study co-author Lukas Hoermayer. 

To investigate plant regeneration, the researchers used a laser to injure the root of a thale cress. Next, they used a microscope to monitor the cells as the wound was healed. 

The scientists found that Auxin, which is essential in plant growth and development, plays a critical role in wound healing. The hormone accumulates in the cells directly adjacent to the wound and facilitates the plant’s response to injury.

When the researchers disrupted the amount of Auxin present, either too many or no cells responded to the wound. This uncoordinated response sometimes led to tumorous swelling of the root.

“Only the precise coordination of many cells throughout the whole tissue yields a defined and localized wound response,” explained Hoermayer.

The team also noticed a pressure change within the plant that was caused by the collapsing cells of the wound. When the scientists reduced the cellular pressure before injuring a plant, the pressure difference vanished and the regeneration ability of the plant was weakened.

The finding that Auxin concentration and pressure changes govern regeneration provides brand new insight into how plant roots manage to heal wounds, survive in sandy soil, or persist in the presence of root-attacking herbivores.

The study is published in the Proceedings of the National Academy of Sciences.

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By Chrissy Sexton, Earth.com Staff Writer