title: Interplay of MYB factors in differential cell expansion, and consequences for tomato fruit development.
abstract: We previously identified SlFSM1 as an early fruit-specific gene encoding a short protein harboring a non-canonical SANT/MYB-like domain. Here, we investigated the role of FSM1 during fruit development in tomato and its mode of action. By analyzing tomato plants ectopically expressing FSM1, we established that it negatively affects cell expansion, particularly of those cells with the highest potential to expand, such as those residing inner to the vascular bundles in the fruit pericarp. This function of FSM1 differs from that of the snapdragon FSM1-like gene, RAD, which through an antagonistic activity with DIV participates in establishing floral asymmetry. Revealing an additional component of the FSM1/RAD regulatory complex, we show here that FSM1 physically interacts with FSB1, a previously uncharacterized factor harboring an atypical MYB repeat. We also demonstrate that FSB1 physically interacts with the transcription factor MYBI, a homolog of DIV. Our results show that the formation of the FSB1-MYBI complex is competed by FSM1, which recognizes in FSB1 the same region as MYBI does. Taken together, these studies expose a function for the FSM1/FSB1/MYBI complex in controlling tomato cell expansion, while revealing a mechanism by which competing MYB-MYB interactions could participate in the control of gene expression.
authors.affiliation: Plant Biotechnology Center and Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Katja
authors.initials: K
authors.lastname: Machemer
authors.forename: Oxana
authors.initials: O
authors.lastname: Shaiman
authors.forename: Yehiam
authors.initials: Y
authors.lastname: Salts
authors.forename: Sara
authors.initials: S
authors.lastname: Shabtai
authors.forename: Irina
authors.initials: I
authors.lastname: Sobolev
authors.forename: Eduard
authors.initials: E
authors.lastname: Belausov
authors.forename: Erich
authors.initials: E
authors.lastname: Grotewold
authors.forename: Rivka
authors.initials: R
authors.lastname: Barg
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D049108:Cell Enlargement; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D005638:Fruit / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008957:Models, Genetic; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D018749:RNA, Plant / Q000235:genetics; D013997:Time Factors; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D010940:Plant Proteins; D018749:RNA, Plant; D014157:Transcription Factors