Figure 1. A system for high-throughput imaging of Arabidopsis roots .

(A) Mean (± SE) root lengths of wild-type (Col-0) seedlings after 8 days of growth in magenta vessels with plant nutrient media supplemented with 0%, 0.125%, 0.5%, 0.75% or 1% India Ink (n=15). Asterisks indicate a statistically significant difference in root length when compared to mock treatment using a Two-tailed T-test assuming unequal variation (* = p ≤ 0.05). (B) Representative image of wild-type (Col-0) seedlings after 8 days of growth in magenta vessels with plant nutrient media supplemented with 0%, 0.125%, 0.5%, 0.75% or 1% India Ink. (C) Schematic of the experimental setup. Plant growth media is poured into coverglass-bottom multiwell plates. Once solidified, sterilized Arabidopsis seed is plated on the media surface and plates incubated in a plant growth incubator. The roots of the germinated seedlings grow downward with the gravity vector and follow the surface of the coverglass. Images are then acquired with an inverted fluorescence microscope. (D) Images of 8-day-old seedlings carrying DR5:GFP and grown under the indicated India Ink level in coverglass-bottom 24-well plates. Left, top view of plate. Right, bottom view of fluorescence images. Out-of-focus light from cotyledon autofluorescence is increasingly blocked with increased ink. (E) Arabidopsis roots expressing DR5:GFP on media supplemented with 0%, 0.125%, 0.25% or 0.5% India Ink.