Background and Aims The OVATE gene encodes a nuclear-localized regulatory protein belonging to a distinct family of plant-specific proteins known as the OVATE family proteins (OFPs). OVATE was first identified as a key regulator of fruit shape in tomato, with nonsense mutants displaying pear-shaped fruits. However, the role of OFPs in plant development has been poorly characterized.

Methods Public databaseswere searched and a total of 265 putativeOVATE protein sequenceswere identified from 13 sequenced plant genomes that represent the major evolutionary lineages of land plants. A phylogenetic analysis was conducted based on the alignment of the conserved OVATE domain from these 13 selected plant genomes. The expression patterns of tomato SlOFP geneswere analysed via quantitative real-time PCR. The pattern ofOVATEgene duplication resulting in the expansion of the gene family was determined in arabidopsis, rice and tomato.

Key Results Genes for OFPs were found to be present in all the sampled land plant genomes, including the earlydiverged lineages, mosses and lycophytes. Phylogenetic analysis based on the amino acid sequences of the conserved OVATEdomain defined 11 sub-groups of OFPs in angiosperms. Different evolutionary mechanisms are proposed for OVATE family evolution, namely conserved evolution and divergent expansion. Characterization of the AtOFP family in arabidopsis, the OsOFP family in rice and the SlOFP family in tomato provided further details regarding the evolutionary framework and revealed a major contribution of tandem and segmental duplications towards expansion of the OVATE gene family.

Conclusions This first genome-wide survey on OFPs provides newinsights into the evolution of theOVATEprotein family and establishes a solid base for future functional genomics studies on this important but poorly characterized regulatory protein family in plants.