Phenotyping roots in darkness: disturbance-free root imaging with near infrared illumination

Abstract

Abstract. Root systems architecture (RSA) and size properties are essential determinants of plant performance and need to be assessed in high-throughput plant phenotyping platforms. Thus, we tested a concept that involves near-infrared (NIR) imaging of roots growing along surfaces of transparent culture vessels using special long pass filters to block their exposure to visible light. Two setups were used to monitor growth of Arabidopsis, rapeseed, barley and maize roots upon exposure to white light, filter-transmitted radiation or darkness: root growth direction was analysed (1) through short-term cultivation on agar plates, and (2) using soil-filled transparent pots to monitor long-term responses. White light-triggered phototropic responses were detected for Arabidopsis in setup 1, and for rapeseed, barley and maize roots in setups 1 and 2, whereas light effects could be avoided by use of the NIR filter thus confirming its suitability to mimic darkness. NIR imagederived 'root volume' values correlated well with root dry weight. The root system fractions visible at the different pot sides and in different zones revealed species-and genotype-dependent variation of spatial root distribution and other RSA traits. Following this validated concept, root imaging setups may be integrated into shoot phenotyping facilities in order to enable root system analysis in the context of whole-plant performance investigations.

The platform GrowScreen-Agar enables identification of phenotypic diversity in root and shoot growth traits of agar grown plants

“…When the shoots grow outside the plate, the roots can be shaded, while, when the shoot is grown inside the plate light reaching the root cannot be avoided. Recently, it has been shown that light triggers phototropic responses, reduces root growth, but promotes the emergence of lateral roots of Arabidopsis plants [41,42]. These modifications in lateral root development resulted in a higher root length density of light grown plants similar as presented in our study for plants with the shoot inside the plate (Fig.…”

A Phenotyping Protocol for Detailed Evaluation of Apple Root Resistance Responses Utilizing Tissue Culture Micropropagated Apple Plants

“…The continuous evaluation and documentation of apple root necrosis progression patterns has never reported. Minirhizotron and MNR technology-based imaging technologies are being actively developed with the aim of uncovering agronomical or horticultural traits of roots such as root growth and root system architecture under natural soil condition [29] [30]. However, these technologies may not immediately applicable to define the detailed root resistance traits; for example, the subtle change of tissue necrosis such as coloration is difficult to detector define by the current form of these technologies.…”

Combining Ability and Heterosis of Maize Genotypes under Water Stress during Seed Germination and Seedling Emergence

“…Shoots continue to lengthen, whereas roots become thinner, depending on the intensity and duration of stress. As part of the plant-soil interface, roots are exposed to a range of environmental factors, which leads to an adjustment of the spatial arrangement of root systems that enables plants to optimize the usage of the available soil volume, the supply of nutrients to the shoot, and plant performance in general (Shi et al, 2018). As part of the plant-soil interface, roots are exposed to a range of environmental factors, which leads to an adjustment of the spatial arrangement of root systems that enables plants to optimize the usage of the available soil volume, the supply of nutrients to the shoot, and plant performance in general (Shi et al, 2018).…”

“…According to Lisar et al (2012), the root/shoot ratio increases in water stress conditions to facilitate the absorption of water and keep osmotic pressure. As part of the plant-soil interface, roots are exposed to a range of environmental factors, which leads to an adjustment of the spatial arrangement of root systems that enables plants to optimize the usage of the available soil volume, the supply of nutrients to the shoot, and plant performance in general (Shi et al, 2018). Thus, the evaluation of root traits can contribute to the improvement of yield and drought tolerance (Saengwilai et al, 2014;Pestsova et al, 2016).…”

“…The heritability of these traits remains higher than the heritability of grain yield under stress, since they are less influenced by environment, and if observed before plant maturity, selection for water stress tolerance can be performed at early breeding stages (Musvosvi et al, 2018;Wattoo et al, 2018). In this sense, the phenotypic evaluation of the physiological quality of seeds and of the performance of seedlings can be an excellent tool for plant breeding, since it requires little time and space, is relatively easy and quick to evaluate, and may be repeated several times throughout the year to assist breeding programs (Meeks et al, 2013;Pace et al, 2014;Pestsova et al, 2016;Shi et al, 2018;Wattoo et al, 2018).…”