Carpels

arpels are the female reproductive organs within a flower that enclose the ovules, protecting them and screening out inappropriate pollen. Genes controlling carpel and ovule initiation, identity and patterning are being discovered in the model species Arabidopsis thaliana. Many of these encode transcription factors, including MADS, bHLH, zinc finger and homeodomain family members. Gene regulatory networks (GRNs) are being deduced, including genes involved in auxin and cytokinin action. Carpels arose from leaf-like organs in the ancestor of flowering plants. Ovules arose much earlier in the ancestor of seed plants. The origin of control genes is being deduced by matching the phylogeny of regulatory genes with the phylogeny of land plants. Such comparative evo-devo studies confirm the leaf-like origin of both carpel valves and ovule integuments.