Figure 2.

Different constitutive promoters from the standard genetic parts library show varying levels of activity in Medicago truncatula. Multigene constructs containing promoters from the standard genetic parts library driving expression of the β‐glucuronidase ( GUS ) reporter gene, plus a constitutively expressed firefly luciferase gene ( LUC ; see figure inset), were expressed in M. truncatula via Agrobacterium rhizogenes‐mediated transformation. GUS and LUC reporter gene activities were quantified using a plate reader, and relative promoter activity was calculated by determining the GUS to LUC ratio (with normalization to the pOsAct1 promoter, set at 1). Data represent mean ± standard error from three independent biological replicates. Dotted line in figure inset represents 2.5 kb of plasmid sequence that was unchanged between constructs containing different test promoters. Colour coding: control p35S promoter, grey; constitutive promoters, red; light and dark shades denote promoters from dicotyledonous and monocotyledonous species, respectively. No GUS expression was observed with the pOsEIF5 promoter.