Trait-Based Root Phenotyping as a Necessary Tool for Crop Selection and Improvement

Abstract

Most of the effort of crop breeding has focused on the expression of aboveground traits with the goals of increasing yield and disease resistance, decreasing height in grains, and improvement of nutritional qualities. The role of roots in supporting these goals has been largely ignored. With the increasing need to produce more food, feed, fiber, and fuel on less land and with fewer inputs, the next advance in plant breeding must include greater consideration of roots. Root traits are an untapped source of phenotypic variation that will prove essential for breeders working to increase yields and the provisioning of ecosystem services. Roots are dynamic, and their structure and the composition of metabolites introduced to the rhizosphere change as the plant develops and in response to environmental, biotic, and edaphic factors. The assessment of physical qualities of root system architecture will allow breeding for desired root placement in the soil profile, such as deeper roots in no-till production systems plagued with drought or shallow roots systems for accessing nutrients. Combining the assessment of physical characteristics with chemical traits, including enzymes and organic acid production, will provide a better understanding of biogeochemical mechanisms by which roots acquire resources. Lastly, information on the structural and elemental composition of the roots will help better predict root decomposition, their contribution to soil organic carbon pools, and the subsequent benefits provided to the following crop. Breeding can no longer continue with a narrow focus on aboveground traits, and breeding for belowground traits cannot only focus on root system architecture. Incorporation of root biogeochemical traits into breeding will permit the creation of germplasm with the required traits to meet production needs in a variety of soil types and projected climate scenarios.

Applications of Multi-Omics Technologies for Crop Improvement

“…Furthermore, roots could be imaged in laboratories and greenhouses without damaging plant samples. For example electrical resistance tomography, electrical capacitance, X-ray computed tomography, and positron emission tomography were used to image root system for soil-grown plants and crops (McGrail et al, 2020). Red, green, blue (RGB) imaging, based on visible light, is a phenotyping tool used to estimate canopy and root systems (Großkinsky et al, 2018).…”

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

“…In this review, we focus exclusively on root system visualization. Several root imaging methods have been reported but there is no standard methodology as each method has its advantages and disadvantages (McGrail et al 2020). Before starting RSA studies, it is necessary to establish whether the plants are grown under field or controlled conditions.…”

“…Second, the ideal root systems for optimal crop growth are unknown as they vary with environmental conditions. Several approaches have been used for phenotyping root systems and various methods including both nondestructive and effective methods have been reported (Atkinson et al 2019, Guimarães et al 2020, McGrail et al 2020, Tardieu et al 2017.…”

A Toolkit to Rapidly Modify Root Systems Through Single Plant Selection

“…These screening techniques can be applied to develop populations enriched with desired root traits for subsequent eld evaluation. By applying cost-effective screening and selection in early generations more labour intensive and expensive eld testing can be performed in later generations using a smaller set of elite materials [19].…”