Fig. 1: Use of RPM mini-phytotron to analyse root growth parameters under various light scenarios.
a RPM and mini-phytotron for simulated microgravity experiments containing five slots to test vertical plant growth on sterile agar plates with variable intensity LED light. The plates were transferred from the growth room, the root tip positions were marked (with a horizontal scratch on the plate surface) and growth was measured after 48 h. b Roots metrics were measured as per published figure9 using ImageJ. Primary root length was calculated by tracing along each root length (L), VGI was calculated as the ratio of root displacement along the y-axis (Ly/L), HGI as the ratio of root tip displacement along the x-axis (Lx/L) and root straightness as the length of chord connecting the starting position to the primary root tip (Lc) normalised to length of the root (L). Angle B was calculated as the angle of root displacement from the vertical being zero degrees. c Example of a plate with Arabidopsis mutant and wild-type Col-0 plants growing in Earth 1 g in darkenss. d Example of Arabidopsis mutant and wild-type Col-0 plants in simulated zero g in darkness. Roots can be seen to lose directionality beyond each horizontal scratch mark on the plate surface (scale bar = 0.5 cm). (Roots grow and bend at the root tip, which is beyond the scratch mark).
