Fig. 5. Developmental phenotype of the cblA^– strain. (A) cblA^– cells and control Ax2 cells were allowed to develop on water-agar to the slug stage (left) and late culmination stage (right) and photographed under phase-contrast optics. The arrows on the cblA^– slugs indicate the break points that are a common feature of DIF signalling mutants and the arrows on the Ax2 culminants show the position of the basal disc. (B) cblA^– cells and control Ax2 cells were transformed with an ecmAO-lacZ reporter construct. This reporter is expressed in all the major prestalk and stalk cell sub-types. The transformed cells were allowed to develop on nitrocellulose filters to the late culmination stage then fixed and stained with X-Gal.