Washington, Oct 15 (IANS) Siblings, grown from the seeds of the same mother, play nice when planted next to each other. But the moment one of them is thrown in with strangers, it begins competing by rapidly growing more roots to take up the water and mineral nutrients.
This discovery was made by Susan Dudley, evolutionary plant ecologist at the McMaster University in Hamilton. So when Harsh Bais, assistant professor of soil science, University of Delaware (UD), who has researched plant signalling systems, read Dudley’s study, he wanted to find the mechanism behind the sibling recognition.

“Plants have no visible sensory markers, and they can’t run away from where they are planted,” Bais says. “It then becomes a search for more complex patterns of recognition.”

Bais says he and his colleagues have also noticed that as sibling plants grow next to one another, their leaves often touch and intertwine compared to strangers that grow rigidly upright and avoid touching.

Besides, strangers planted next to one another are often shorter, Bais notes, because so much of their energy is directed at root growth. Since siblings aren’t competing against one another, their roots tend to be much shallower.

Bais did his masters in biotechnology engineering at Birla Institute of Technology & Sciences (BITS), Pilani in 1996 and his Ph.D under G.A. Ravishankar, Central Food Technological Research Institute, Mysore, India.

Working in his lab at the UD Delaware Biotechnology Institute, Bais and doctoral student Meredith Biedrzycki set up a study with wild populations of Arabidopsis thaliana.

In a series of experiments, young seedlings were exposed to liquid media containing the root secretions or exudates from siblings, from strangers (non-siblings), or only their own exudates.

The length of the longest lateral root and of the hypocotyl, the first leaf-like structure that forms on the plant, were measured.

The exposure of plants to the root exudates of strangers induced greater root formation

than exposure of plants to sibling exudates.

Biedrzycki did the painstaking lab research, rotating more than 3,000 plants involved in

the study, over seven consecutive days and documenting the root patterns, says a UD release.

“This manuscript is very important for my research since (it) has allowed me to probe the natural mechanism of kin recognition and root secretion,” Biedrzycki notes. The study was replicated by Dudley’s lab in Canada, with similar results.

These findings were reported in Communicative & Integrative Biology.