Fig. 1

The Phytostrip growth device and stages in setting up the assay plates. a Line diagram showing two views of the custom-made Phytostrip. The Phytostrips (registered EU Community design no. 002115956) are manufactured in clear polypropylene to allow roots to be readily imaged. The wells of the Phytostrip are 22 mm in length and taper from top to bottom; the internal dimension of each well from front to back is uniformly 2 mm. b A set of 12 Phytostrips resting in a 96-well microtitre plate and held together with a custom-made clamping device to allow them to be moved as a block (top) and then inverted and sealed at the base with adhesive film (bottom) so that they can be filled with molten Phytagel medium. c Image showing three stages (from right to left) in the assembly of the assay plates in their plastic growth boxes. Each of the nine positions in a plate-holder has three separate sections with different layers of indentation (see Additional file 1: Figure S2). The innermost and lowest layer is a reservoir which holds a moistened blotting pad and is kept topped up with water to maintain humidity around the assay plates. The middle layer holds the assay plate in position above the blotting pad. The upper layer provides a holder for the clear plastic growth box that completes the assembly. The plate-holder is located in a fixed position on the robotic plinth by angle brackets so that the robotic arm can accurately locate each Phytostrip by its x, y coordinates. d Diagram showing a cross-section of a Phytostrip in place, seated on a 96-well microtitre plate. The Phytostrip is filled with nutrient gel and seed sown on the surface of the gel germinates and roots grow down through the gel where they can be imaged through the transparent walls of the Phytostrip. (Shoot development can also be followed by imaging from above). The Phytostrip is shown in contact with liquid medium contained in the wells of the microtitre plate. Chemical treatments can be applied by adding compounds of interest to the liquid medium and these are able to diffuse through the gel to be absorbed by the growing roots