Functional conservation of the grapevine candidate gene INNER NO OUTER for ovule development and seed formation

Abstract

AbstractSeedlessness represents a highly appreciated trait in table grapes. Based on an interesting case of seedless fruit production described in the crop speciesAnnona squamosa, we focused on theVitis vinifera INNER NO OUTER (INO)gene as a candidate. This gene encodes a transcription factor belonging to theYABBYfamily involved in the determination of abaxial identity in several organs. InArabidopsis thaliana, this gene was shown to be essential for the formation and asymmetric growth of the ovule outer integument and its mutation leads to a phenotypic defect of ovules and failure in seed formation. In this study, we identified in silico theV. viniferaorthologue and investigated its phylogenetic relationship toINOgenes from other species and its expression in different organs in seeded and seedless varieties. Applying cross-species complementation, we have tested its functionality in the Arabidopsisino-1 mutant. We show that theV. viniferaINO successfully rescues the ovule outer integument growth and seeds set and also partially complements the outer integument asymmetric growth in the Arabidopsis mutant, differently from orthologues from other species. These data demonstrate that VviINO retains similar activity and protein targets in grapevine as in Arabidopsis. Potential implications for grapevine breeding are discussed.