The effect of ACCase inhibition on PHB production in transgenic switchgrass and sugarcane. (A) PHB (bars) and total fatty acid (lines) content in 30 leaves of in vitro propagated switchgrass plantlets treated with various concentrations of the ACCase inhibitor quizalofop. Shaded and clear bars or circles represent two independent transgenic events. (B) PHB content in leaves of increasing maturity (L1 is the youngest leaf and L5 is the most mature one) from soil grown sugarcane plants treated with various concentrations of the ACCase inhibitor fluazifop-p-butyl (Bars: white = 0 μM, grey = 20 μM, black = 100 μM). PHB levels which are significantly different to the untreated control are indicated: **P < 0.001; *P < 0.05). C, D, E Nile Blue A stained leaf sections from in vitro propagated switchgrass plants: C, WT; D, untreated PHB producing plant; E, PHB producing plant treated with 100 μM quizalofop. F, G, H, Nile Blue A stained leaf sections from soil-grown sugarcane plants treated with: F, WT; G, untreated PHB producing plant; H, PHB producing plant treated with 100 μM fluazifop. Note the abundance of PHB granules in the M tissue in the Nile Blue A stained sections from treated switchgrass and sugarcane PHB producers.