Evolution and conserved functionality of organ size and shape regulator PEAPOD.

Ruth Cookson,Hong Xue,Greg Bryan,Ambarish Biswas,Kim Richardson,Aurelie Laugraud,Roger Moraga,Somrutai Winichayakul,Nick Roberts,Hector Candela

doi:10.1371/journal.pone.0263928

Abstract

Transcriptional regulator PEAPOD (PPD) and its binding partners comprise a complex that is conserved throughout many core eudicot plants with regard to protein domain sequence and the function of controlling organ size and shape. Orthologues of PPD also exist in the basal angiosperm Amborella trichopoda, various gymnosperm species, the lycophyte Selaginella moellendorffii and several monocot genera, although until now it was not known if these are functional sequences. Here we report constitutive expression of orthologues from species representing diverse taxa of plant phylogeny in the Arabidopsis Δppd mutant. PPD orthologues from S. moellendorffii, gymnosperm Picea abies, A. trichopoda, monocot Musa acuminata, and dicot Trifolium repens were able to complement the mutant and return it to the wild-type phenotype, demonstrating the conserved functionality of PPD throughout vascular plants. In addition, analysis of bryophyte genomes revealed potential PPD orthologues in model liverwort and moss species, suggesting a more primitive lineage for this conserved regulator. The Poaceae (grasses) lack the genes for the PPD module and the reason for loss of the complex from this economically significant family is unclear, given that grasses were the last of the flowering plants to evolve. Bioinformatic analyses identified putative PPD orthologues in close relatives of the Poaceae, indicating that the explanation for absence of PPD in the grasses may be more complex than previously considered. Understanding the mechanisms which led to loss of PPD from the grasses will provide insight into evolution of the Poaceae.

Highlights

PPD gene sequences from a range of species were synthesized with flanking attL sites (GenScript Biotech, China) and cloned into expression cassettes to enable over expression from the Cauliflower Mosaic Virus 35S (CaMV35S) promoter [28] when transformed into the Arabidopsis Δppd mutant [9]
The Arabidopsis PPD domain [4] was used to search the plant genome and protein data bases; strong matches were identified in the true vascular plants including the lycophyte S. moellendorffii
Despite the highly conserved domain sequence and function of PPD throughout rosid and asterid plants, until now it was not known if the PPD orthologues in other clades encoded functional proteins

Summary

Introduction

The production of new organs throughout the life cycle of a plant is an ongoing and flexible process. This plasticity utilizes pluripotent cells which receive signals via specific genetic switches to co-ordinate the temporal and spatial division, differentiation, and expansion of the cells. Transcription factors control and co-ordinate the expression of a range of genes involved in a common process or pathway while transcriptional regulators enable or suppress the functionality of transcription factors.

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Results

Discussion

Conclusion