Responses of root system architecture to water stress at multiple levels: A meta-analysis of trials under controlled conditions

Abstract

Plants are exposed to increasingly severe drought events and roots play vital roles in maintaining plant survival, growth, and reproduction. A large body of literature has investigated the adaptive responses of root traits in various plants to water stress and these studies have been reviewed in certain groups of plant species at a certain scale. Nevertheless, these responses have not been synthesized at multiple levels. This paper screened over 2000 literatures for studies of typical root traits including root growth angle, root depth, root length, root diameter, root dry weight, root-to-shoot ratio, root hair length and density and integrates their drought responses at genetic and morphological scales. The genes, quantitative trait loci (QTLs) and hormones that are involved in the regulation of drought response of the root traits were summarized. We then statistically analyzed the drought responses of root traits and discussed the underlying mechanisms. Moreover, we highlighted the drought response of 1-D and 2-D root length density (RLD) distribution in the soil profile. This paper will provide a framework for an integrated understanding of root adaptive responses to water deficit at multiple scales and such insights may provide a basis for selection and breeding of drought tolerant crop lines.

Understanding role of roots in plant response to drought: Way forward to climate‐resilient crops

“…When under stress, plants generally maintain a high root–shoot ratio in order to allow higher resource allocation toward roots for enhanced water and nutrient absorption (Kou et al., 2022). Roots are the most crucial part that helps plants adapt better in a water‐limited environment by maintaining plant fitness.…”

“…Acquisition of resources from soil is largely dependent on the architecture of the root, and any changes in this architecture significantly affect resource capture efficiency in plants (Morris et al., 2017). RSA is defined as the spatial configuration of roots that help plants anchor and forage for nutrients and water in soil domains (Kou et al., 2022). RSA is determined by a variety of root traits such as root angle, root‐to‐shoot ratio, root length, root hair, root diameter, root biomass, and root tip (Siddiqui et al., 2021).…”

“…Several TFs are also involved in regulating root development during stress conditions (Kou et al., 2022). In Chrysanthemum , TFs, such as CgDREBa, are known to activate ROS scavengers such as SOD and peroxide dismutase (S. Chen et al., 2011).…”

Prospects Of Developing Drought Resilience In Crop Plants Through Strategic Modifications In Root System Architecture

“…It has been reported that response of RSA to drought varies considerably at intra-and interspecies level (Kou et al, 2022). Ability of plant to survive and maintain its yield under water scarce conditions is regarded as the plant plasticity response which confers drought tolerance to it (Gao et al, 2015;Suseela et al, 2020).…”

“…It has been proposed that root traits helps in reducing the root system cost (including greater formation of aerenchyma, smaller root diameter, reduced area of living tissue, increased size of cortical cell, fewer nodal roots, root cortical senescence) and aid in promoting elongation of roots, hence increased capture of resources and deeper exploration of soil (Lynch 2013;Fonta et al, 2022). Steeper angle of root growth is known to improve drought tolerance, for example, in rice, deeper rooting 1 (dro1 ) gene which is responsible for influencing angle of root growth has been used in breeding programs and cloning experiments extensively (Uga et al 2013;Kitomi et al 2015;Kou et al, 2022). The number and size of metaxylem also affects drought tolerance and water use efficiency in plants.…”