Shaping up the fruit: control of fruit size by an Arabidopsis B-sister MADS-box gene.

The final size and shape of fruits is determined by organogenesis. Organogenesis is the coordination of cell growth, cell differentiation and pattern formation. Individual genes have been identified that affect lateral organ growth. A majority of these characterized growth genes in Arabidopsis affect all lateral plant organs and few of these have been placed into a regulatory network controlling organ growth. We have recently characterized GORDITA (GOA), a MADS-box transcription factor, which represses cell expansion specifically in fruits and affects overall fruit size.1 Here we provide insights into a possible regulatory network in which GOA can function to regulate fruit growth. We further suggest how duplicated B-sister genes; GOA and TRANSPARENT TESTA 16 (TT16) could have acquired distinct regulatory roles.