Apple SVP Family MADS-Box Proteins and the Tomato Pedicel Abscission Zone Regulator JOINTLESS have Similar Molecular Activities

• Published in: Plant and cell physiology Vol. 56; no. 6; pp. 1097 - 1106
• Main Authors: Nakano, Toshitsugu, Kato, Hiroki, Shima, Yoko, Ito, Yasuhiro
• Format: Journal Article
• Language: English
• Published: Japan 01.06.2015
• Subjects: Down-Regulation - genetics; Electrophoretic Mobility Shift Assay; Flowers - metabolism; Fruit - metabolism; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Lycopersicon esculentum - genetics; Lycopersicon esculentum - growth & development; Lycopersicon esculentum - metabolism; MADS Domain Proteins - genetics; MADS Domain Proteins - metabolism; Malus - genetics; Malus - growth & development; Malus - metabolism; Multigene Family; Mutation - genetics; Phenotype; Phylogeny; Plant Proteins - genetics; Plant Proteins - metabolism; Protein Binding; Protein Interaction Mapping; Two-Hybrid System Techniques; MADS-box; Apple; JOINTLESS; Tomato; Abscission
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcv034

Pedicel abscission occurs widely in fruit-bearing plants to detach ripe, senescent or diseased organs, and regulation of abscission plays a substantial role in regulating yield and quality in fruit crops. In tomato, development of pedicel abscission zones (AZs) requires the MADS-box genes JOINTLESS (J), MACROCALYX (MC) and SlMBP21. In other plants, however, the involvement of MADS-box genes in pedicel abscission remains unclear. Here, we used genetic and biochemical methods to characterize apple J homologs in the context of the regulation of abscission in tomato. We identified three genes encoding two J homologs, MdJa and MdJb. Similarly to J, MdJa and MdJb interacted with MC and SlMBP21, but their interactions differed slightly: like J, MdJb formed a multimer (probably a tetramer) with SlMBP21; however, MdJa formed multimers to a lesser extent. Ectopic expression of MdJb in a J-deficient tomato mutant restored development of functional pedicel AZs, but ectopic expression of MdJa did not complement j mutants. Introduction of MdJb also restored expression of J-dependent genes in the mutant, such as genes for polygalacturonase, cellulase and AZ-specific transcription factors. These results suggest a potentially conserved mechanism of pedicel AZ development in apple and other plants, regulated by MADS-box transcription factors.