Scientists have discovered a hidden layer of identity in plant root cells: an “environmental mode” that switches on in some cells and becomes more common when water is scarce.
Led by the Harry Perkins Institute of Medical Research, Professor Ryan Lister AM and Dr Marina Oliva both from the ARC Centre of Excellence in Plants for Space and The University of Western Australia’s School of Molecular Sciences, the study published in Nature examined how plants cells respond to drought conditions.
Prof Ryan Lister AM, Left; Dr Marina Oliva, Right
Professor Lister from the Perkins and UWA said the discovery had been invisible to older methods of analysis that averaged thousands of cells together.
“Plants can’t move to escape bad conditions, so they need ways to adapt to changes in their environment,” said Professor Lister.
“This discovery suggests that one method roots do this is by shifting the balance between the two states their cells can adopt, almost like turning a dial.
“Understanding how roots respond to water and nutrients is central to growing crops that cope with drought on Earth, and to growing plants in the controlled environments of vertical farms and space missions.”
Researchers read the gene activity of hundreds of thousands of individual cells from the root tip of the model plant Arabidopsis.
The team found almost every cell type splits into two groups: cells that switch on a shared set of hundreds of genes involved in responding to environmental conditions, and cells that do not switch these on.
“Roots have long been described as a set of well-defined, distinct cell types, each following a single path from young cell to mature cell,” said Dr Oliva.
“We expected each cell type to have one story, but instead found that every cell type has two.
“What separates them is that one group activates an extra set of genes linked to environmental responses.
“What was really striking was that when we changed the growing conditions, the root responded by changing how many cells switched on this extra program.”
The response was influenced by abscisic acid, the plant hormone that coordinates drought responses.
Plants unable to make or sense the hormone had far fewer cells in this mode, while plants grown with limited water had many more, rising from about four in 10 cells to two in three.
The study involved researchers at La Trobe University, the Walter and Eliza Hall Institute, A*STAR Singapore and Zhejiang University.
