The cover for New Phytologist 217:3 is rather special, being the first cover to feature a hand-drawn image since 2004. In this instalment of Behind the Cover, authors Claire Stanley and Guido Grossmann reveal more detail about the dual-flow-RootChip, the subject of their recent Methods paper.
The artwork illustrates the dual-flow-RootChip, a new technology that enables root nutrition, signalling and development to be investigated in controlled asymmetric conditions at the level of single organs and cells. The heterogeneous nature of the ‘below-ground’ soil environment experienced by plant roots (e.g. nutrient and microbe availability) and the use of microfluidic technology and microscopy are also emphasised in the artwork.
We used a combination of so-called ‘microfluidic’ or ‘Lab-on-a-Chip’ technology and fluorescence microscopy to enable us to zoom into the microscale and therefore visualise how plant roots respond to treatments applied asymmetrically. Microfluidic technology facilitates the manipulation of fluidics on the microscale and we take advantage of laminar flow regimes to control the microenvironment around plant roots.
In natural soil environments, roots are exposed to a plethora of environmental stimuli, ranging from heat to cold stress, from pathogen attack to symbiosis, or from high salinity to low nutrient availability. All of these stimuli have an impact on plant growth and development and eventually shape the architecture of the root system. While plant scientists typically test one condition at a time, roots have to deal with an environmental complexity in nature that is challenging to reproduce in the lab. Being able to take such environmental complexity into account, may, however, be the key to comprehensively understand plant development.
The aim our research was to develop technology that allows the creation of asymmetric microenvironments for single roots in a controlled manner and study responses to diverse conditions on the levels of gene expression, signalling and development. In the future, this technology will contribute to a better understanding of root-environment interactions and may help to unveil in which ways the plant is capable to prioritise its responses to adapt to natural conditions.
The dual-flow-RootChip is depicted in the centre of the artwork and illustrates the new microfluidic platform that has been described in our methods article. It shows a plant root that is growing within a microchannel and guided by triangular-shaped pillars. This enables root growth to be directed through the centre of the microchannel and therefore one side of the growing root to be treated differently to the other. The blue and the red ‘streams’ represent the different treatments that are applied to the root. We observed that asymmetric nutrient conditions, for example, resulted in an adaptation of the root hair response and is exemplified by the artwork, i.e. longer root hairs in the ‘blue’ treatment vs shorter root hairs in the ‘red’ treatment. As these miniscule events have to be visualised using microscopy, a microscope objective was included to signify this aspect of the work.
Read the paper: Stanley, C. E., Shrivastava, J., Brugman, R., Heinzelmann, E., van Swaay, D. and Grossmann, G. (2017) Dual-flow-RootChip reveals local adaptations of roots towards environmental asymmetry at the physiological and genetic levels. New Phytologist. doi: 10.1111/nph.14887