Root phenotyping: from component trait in the lab to breeding: Table 1.

Abstract

In the last decade cheaper and faster sequencing methods have resulted in an enormous increase in genomic data. High throughput genotyping, genotyping by sequencing and genomic breeding are becoming a standard in plant breeding. As a result, the collection of phenotypic data is increasingly becoming a limiting factor in plant breeding. Genetic studies on root traits are being hampered by the complexity of these traits and the inaccessibility of the rhizosphere. With an increasing interest in phenotyping, breeders and scientists try to overcome these limitations, resulting in impressive developments in automated phenotyping platforms. Recently, many such platforms have been thoroughly described, yet their efficiency to increase genetic gain often remains undiscussed. This efficiency depends on the heritability of the phenotyped traits as well as the correlation of these traits with agronomically relevant breeding targets. This review provides an overview of the latest developments in root phenotyping and describes the environmental and genetic factors influencing root phenotype and heritability. It also intends to give direction to future phenotyping and breeding strategies for optimizing root system functioning. A quantitative framework to determine the efficiency of phenotyping platforms for genetic gain is described. By increasing heritability, managing effects caused by interactions between genotype and environment and by quantifying the genetic relation between traits phenotyped in platforms and ultimate breeding targets, phenotyping platforms can be utilized to their maximum potential.

Roots Withstanding their Environment: Exploiting Root System Architecture Responses to Abiotic Stress to Improve Crop Tolerance

“…In the last decade a wide range of new and improved methods to research roots in a more natural environment have been developed (as reviewed in Zhu et al, 2011; Downie et al, 2015; Judd et al, 2015; Kuijken et al, 2015). Most systems are based on either a transparent growth medium or a medium from which the roots can easily be removed without damage.…”

“…A wide range of root image analysis software exists (as reviewed in Lobet et al, 2013; Spalding and Miller, 2013; Kuijken et al, 2015). These tools range from automated to non-automated.…”

A New Phenotyping Pipeline Reveals Three Types of Lateral Roots and a Random Branching Pattern in Two Cereals

“…The root system is by nature hidden, and root phenotyping platforms have to make a compromise between the relevance of growth conditions and trait measurement feasibility. Most root phenotyping platforms focus on measurements at high throughput of selected root traits on a large number of plants, with the objective of detecting quantitative trait loci usable in breeding (Kuijken et al, 2015). For example, Atkinson et al (2015) reported a phenotyping platform where root systems grow in 2D on a filter paper for a few days.…”

Breeding wheat for drought adaptation: Development of selection tools for root architectural traits

“…In addition, root measurements tend to be more precise and more reproducible because the plants are grown in a more homogeneous environment compared to the field. Despite many innovations in root phenotyping over the last few years (Paez-Garcia et al, 2015;Kuijken et al, 2015), suitable methods for large breeding populations are still needed.…”

“…In the recent years, methods for phenotyping root traits have been developed in controlled environment conditions and in the field (Paez-Garcia et al, 2015;Kuijken et al, 2015).…”