The PLURIPETALA gene and its role in meristem signaling events

     The pluripetala (plp) mutant was identified as an enhancer of meristem activity in ectopic meristems of 35S::KNAT1 plants (see Identifying genes involved in meristem function). The most striking plp phenotype is the presence of many extra petals in the flower. plp mutant plants also have larger shoot and floral meristems and increased leaf, flower, and floral organ number, in addition to abnormalities in maturation time, organ development, and hormone responses.

The PLP gene encodes a key protein involved in prenylation, which is a post-translational lipid modification thought to play a role in signaling pathways and protein-protein interactions. Based on the mutant phenotype, PLP plays a role in meristem signaling events that are critical for maintaining correct cell number and establishing primordia initiation sites. Proteins with consensus target sequences for prenylation are readily identifiable using bioinformatics tools, allowing us to further characterize these meristem signaling pathways using reverse genetics and proteomics approaches.

Figure 1. A. Wild type Arabidopsis flowers have a typical crucifer pattern, with 4 sepals. B. plp mutant flowers have many more petals, typically 8-10. The number of sepals, stamens, and carpels are slightly increased in plp.  Click the image to view full size.

Figure 2. plp mutant stems sometime become fasciated, growing as a strap-like structure indicative of a major loss of meristem cell division control.  Click the image to view full size.