Integration of the Plant-Specific PLATZ Transcription Factors into Gene Regulatory Networks Controlling Developmental Processes

The PLant AT-rich protein and Zinc-binding protein (PLATZ) transcription factor family is specific to photosynthetic eukaryotes. These proteins are globally defined by the presence of a PLATZ conserved region and/or two conserved zinc-binding motifs, however exceptions are frequent and other conserved motifs may be present as well. A survey of the presence of these conserved domain and motifs in several PLATZ proteins from different taxa across the evolution revealed PLATZ in rhodophytes and green algae indicating a role for these transcription factors long before terrestrialization. The number of PLATZ increases concomitantly with the apparition of traits specific to land plants, such as embryogenesis, apical growth and phenylpropanoid metabolism, which suggests determining roles of these transcription factors throughout the evolution of Viridiplantae. There are no studies related to PLATZ function in algae or in earlier land plants and the molecular processes involved in PLATZ evolution remain largely unknown. Functional investigations have been reported only in a limited number of angiosperms, for whom PLATZ were described as regulators of cell proliferation, some of which are involved in RNA polymerase III (POL III) and others in POL II machineries. Particularly, several PLATZ have been shown to be involved in the regulation of meristematic activity, in leaf and/or in seed development.