Figure 3: Expression of meristem identity genes in the shoot apex of veg1.

(a) mRNA levels of PIM (left) and DET (right) in the shoot apices of the wild type and veg1. Relative mRNA levels were determined by RT–qPCR. Samples were from main-shoot apices of 2-week old plants (veget. apices), before wild-type plants had gone through the floral transition, and of 5-week-old plants ('inflo' apices), when the wild type had started producing flowers. Values represent the means of two biological replicates ±s.e. (b–e) In situ hybridization of DET mRNA in the shoot apices of wild type and veg1. Samples were from the main apices of 4-week-old plants, when the wild type had gone through the floral transition. In the wild-type apex (b) DET expression was detected below the dome of the primary inflorescence meristem (I₁), in the vasculature, and in the boundary between the secondary inflorescence meristem (I₂) and the incipient leaf primordium (LP), but not in the I₂ or in the floral meristems (F), as represented in the diagram (c), for clarity. Similarly, in veg1, expression was also detected below the primary shoot meristem (I₁ SAM, arrowhead), in a section through the centre of the apex (d). A deeper section from the same apex (e) shows that in veg1 DET is also expressed in a lateral shoot meristem (I₁*, arrowhead).