RADIX: rhizoslide platform allowing high throughput digital image analysis of root system expansion

Abstract

BackgroundPhenotyping of genotype-by-environment interactions in the root-zone is of major importance for crop improvement as the spatial distribution of a plant’s root system is crucial for a plant to access water and nutrient resources of the soil. However, so far it is unclear to what extent genetic variations in root system responses to spatially varying soil resources can be utilized for breeding applications. Among others, one limiting factor is the absence of phenotyping platforms allowing the analysis of such interactions.ResultsWe developed a system that is able to (a) monitor root and shoot growth synchronously, (b) investigate their dynamic responses and (c) analyse the effect of heterogeneous N distribution to parts of the root system in a split-nutrient setup with a throughput (200 individual maize plants at once) sufficient for mapping of quantitative trait loci or for screens of multiple environmental factors. In a test trial, 24 maize genotypes were grown under split nitrogen conditions and the response of shoot and root growth was investigated. An almost double elongation rate of crown and lateral roots was observed under high N for all genotypes. The intensity of genotype-specific responses varied strongly. For example, elongation of crown roots differed almost two times between the fastest and slowest growing genotype. A stronger selective root placement in the high-N compartment was related to an increased shoot development indicating that early vigour might be related to a more intense foraging behaviour.ConclusionTo our knowledge, RADIX is the only system currently existing which allows studying the differential response of crown roots to split-nutrient application to quantify foraging behaviour in genome mapping or selection experiments. In doing so, changes in root and shoot development and the connection to plant performance can be investigated.Electronic supplementary materialThe online version of this article (doi:10.1186/s13007-016-0140-8) contains supplementary material, which is available to authorized users.

Cortical Cell Diameter Is Key To Energy Costs of Root Growth in Wheat

“…Furthermore, high heritability was obtained for root cortical cell diameter ( Table 2). The heritability for cortical cell diameter obtained for wheat in this study is comparable to that of root number, and root and shoot growth rates in wheat and other crops (Li et al, 2015;Richard et al, 2015;Burridge et al, 2016;Le Marié et al, 2016). The significant correlation between root cortical cell diameter and the energy costs of root growth shows that root cortical cell diameter is related to root physiological processes.…”

Accelerating genetic gains in legumes for the development of prosperous smallholder agriculture: integrating genomics, phenotyping, systems modelling and agronomy

“…The University of Western Australia, Australia has developed a semi-hydroponic phenotyping system that examines architecture of deep root system and is amenable for phenotyping large sets of plants in a relatively small space (Chen et al, 2011). The salient features of several high throughput phenotyping platforms, such as PHENOPSIS (Bresson et al, 2015;Granier et al, 2006), PhenoArch (Cabrera-Bosquet et al, 2016), DEEPER PHENOSCOPE (Bresson et al, 2015), and RADIX (Le Marié et al, 2016), are summarized in Table 2. Robotic-assisted imaging platforms and computer visionassisted analysis tools have also been developed for precise phenotyping of physiological growth, development, and other phenotypic properties (Fahlgren et al, 2015a,b).…”

“…• Rhizoslide platform allowing high throughput digital image analysis of root system expansion Le Marié et al (2016) Scanner bank (The James Hutton Institute, UK)…”

RhizoChamber-Monitor: a robotic platform and software enabling characterization of root growth

“…Germination paper has been used as alternative medium for growing roots (in two dimensional (2D) space) due to its low cost and convenience [ 17 – 20 ]. The modes of nutrients supply to the growth medium have been various, such as wick systems from bottom to top [ 18 , 21 ], wick systems from top to bottom [ 19 , 22 ], direct irrigation from top to bottom [ 23 ], spraying a mist on the surface [ 17 ] and infiltration from soil to the material [ 20 , 24 ]. Light-shading methods for germination paper system also varied with the shape and size of the growth vessel.…”

“…However, the high-throughput of root imaging using this method has to increase scanners. Another method, RADIX [ 22 ], involves a long rack for holding a number of rhizoslides with a sliding image station on one side. The top of each rhizoslide is shaded by a cover leaving a hole for shoot growth and the sides of whole rack are shaded by black polyethylene film.…”