Virtual Plants Need Water Too: Functional-Structural Root System Models in the Context of Drought Tolerance Breeding

Abstract

Developing a sustainable agricultural model is one of the great challenges of the coming years. The agricultural practices inherited from the Green Revolution of the 1960s show their limits today, and new paradigms need to be explored to counter rising issues such as the multiplication of climate-change related drought episodes. Two such new paradigms are the use of functional-structural plant models to complement and rationalize breeding approaches and a renewed focus on root systems as untapped sources of plant amelioration. Since the late 1980s, numerous functional and structural models of root systems were developed and used to investigate the properties of root systems in soil or lab-conditions. In this review, we focus on the conception and use of such root models in the broader context of research on root-driven drought tolerance, on the basis of root system architecture (RSA) phenotyping. Such models result from the integration of architectural, physiological and environmental data. Here, we consider the different phenotyping techniques allowing for root architectural and physiological study and their limits. We discuss how QTL and breeding studies support the manipulation of RSA as a way to improve drought resistance. We then go over the integration of the generated data within architectural models, how those architectural models can be coupled with functional hydraulic models, and how functional parameters can be measured to feed those models. We then consider the assessment and validation of those hydraulic models through confrontation of simulations to experimentations. Finally, we discuss the up and coming challenges facing root systems functional-structural modeling approaches in the context of breeding.

The Complex Genetic Architecture of Early Root and Shoot Traits in Flax Revealed by Genome-Wide Association Analyses

“…Root trait measurements provide essential information to facilitate varietal improvement in breeding programs to select superior genotypes especially in nutrient and moisture deficit areas (Comas et al, 2013; Ndour et al, 2017). Root traits have already been used in breeding schemes to select elite genotypes in crops such as wheat for example (Wasson et al, 2014).…”

Functional–structural root-system model validation using a soil MRI experiment

“…Functional–structural root-system models (FSRSM, see Meunier et al , 2017; Ndour et al , 2017) have been developed since the late 1980s (Diggle, 1988; Doussan et al , 2006; Javaux et al , 2008; Schnepf et al , 2018). These models combine root functional and structural information to describe local processes in the soil–root continuum (Passot et al , 2019).…”

Root phenotyping: important and minimum information required for root modeling in crop plants

“…Certain root traits may be used to estimate the input parameters for functional-structural root models simulating RSA dynamics (Freschet et al 2020, Pagès 2016. Functional-structural root models have been extensively used to investigate the relationships between root architectural traits and variability in soil and spatiotemporal nutrient distribution (Dunbabin et al 2013, Ndour et al 2017). These models simulate the structural and spatial distribution of the root system and directly integrate developmental processes such as elongation and branching, and their interaction with root-level soil properties (Pagès and Picon-Cochard 2014).…”