Fig. 2. SPL3 promotes vegetative phase change and floral induction and is repressed by miR156. (A) Structure of constructs used in this study. The sequence of the mutated miR156 target site is illustrated. A wild-type site is indicated by a black line and a mutated site is indicated by a grey line. (B) GUS expression (top) and RT-PCR of GUS mRNA (bottom) in progeny of crosses between transgenic plants constitutively expressing miR156a, and miR156-sensitive or insensitive versions of the GUS-SPL3 mRNA. (C) Morphology of transgenic plants expressing miR156-sensitive (SPL3) and miR156-insensitive (SPL3m, SPL3) versions of SPL3 under the regulation of the 35S promoter. (D) The number of leaves without abaxial trichomes (black), with abaxial trichomes (grey), cauline leaves (white) and flowering time (days after planting, top of bar) for the genotypes illustrated in C (± s.e.m.). Plants transformed with 35S::SPL3 are not significantly different from control plants. 35S::SPL3m and 35S::SPL3 have significantly fewer juvenile, adult and cauline leaves than control plants (n>30 for each genotype, P<0.01). (E) The effect of 35S::SPL3m on the morphology of leaves 1 and 2. This transgene produces a significant decrease in the length of the petiole and a slightly more acute leaf base (n=30 for each genotype; P<0.01).