How plant roots respond to soil stresses

A research reveals how roots actively perceive the microenvironment and activate specific molecular responses. From the study, new prospects for more climate-resilient crops

by Matteo Cavallito

 

Plant roots show an amazing ability to adapt to soil stress conditions. This ability involves several so far unknown mechanisms that enable them to detect the microenvironment and activate cell type-specific molecular responses. This is stated by researchers from several academic institutions. Their investigation, published in the journal Nature, in fact opens new perspectives for the development of crops that are more resilient to climate change. And, therefore, able to contribute more effectively to global food security.

Soil compaction

In the study, which involved the universities of Nottingham (in the United Kingdom) and Ghent (in Belgium) as well as Duke University in Durham (North Carolina), the authors used transcriptomics to observe in real time how rice root cells change their genetic activity to adapt to the soil. The research, in particular, examined root behavior in the laboratory – where the plant grew on a sterile nutrient gel – and in some natural soils with, or without, a stressor in place: compaction.

The authors, in particular, found that the outer tissues show important transcriptional changes in response to soil characteristics.

This means, simplifying, that cells activate molecular mechanisms to respond to potential problems. Soil compaction stress, for example, activates in roots a hormonal response mediated by abscisic acid (ABA). This is produced in the phloem and transported to the outer tissues. Here the acid stimulates the formation of suberin- and lignin-based hydrophobic barriers to reduce water loss and impart mechanical stability.

From roots both genetic and physical responses

Root responses, the authors recall, “are related to nutrient homeostasis, cell wall integrity and defence in response to heterogeneous soil.” The study, moreover, demonstrated “how root tissues communicate and adapt to contrasting soil conditions at single-cell resolution.” Through transcriptomics, in short, the researchers found that root responses to stress are both genetic and physical.

A discovery that, the scientists note, was made possible by observing plant behavior not only in controlled environments. That is, in the laboratory, but also under realistic soil conditions.

“This is the first time such cell-resolution expression tools have been applied to roots grown in soil,” Bipin Pandey, a professor in the School of Biosciences at the University of Nottingham and co-author of the research, explained in a statement. “Understanding root cell-specific responses in a realistic soil environment will pave the way for engineering crops at the cellular level—tailored to work without disrupting critical processes in other root tissues.”

Plants more resilient to climate change

By providing a detailed transcriptional map of roots in soil, the authors explain, the research has enabled a quantum leap in understanding plant physiology outside the controlled conditions typical of a laboratory. Moreover, they add, “As climate change threatens soil quality and agricultural sustainability”, risultati ottenuti “are not just scientifically exciting—they are essential.”

In this context, faced with soils increasingly prone to compaction, erosion and drought, in other words, the knowledge gained will help select crop varieties resilient to stresses. But also optimize nutrient uptake by reducing fertilizers, develop soil management strategies to maintain root functionality and, finally, understand the role of abscisic acid as a regulator of cellular adaptation.