Transient Silencing of CHALCONE SYNTHASE during Fruit Ripening Modifies Tomato Epidermal Cells and Cuticle Properties    

Abstract

Tomato (Solanum lycopersicum) fruit ripening is accompanied by an increase in CHALCONE SYNTHASE (CHS) activity and flavonoid biosynthesis. Flavonoids accumulate in the cuticle, giving its characteristic orange color that contributes to the eventual red color of the ripe fruit. Using virus-induced gene silencing in fruits, we have down-regulated the expression of SlCHS during ripening and compared the cuticles derived from silenced and nonsilenced regions. Silenced regions showed a pink color due to the lack of flavonoids incorporated to the cuticle. This change in color was accompanied by several other changes in the cuticle and epidermis. The epidermal cells displayed a decreased tangential cell width; a decrease in the amount of cuticle and its main components, cutin and polysaccharides, was also observed. Flavonoids dramatically altered the cuticle biomechanical properties by stiffening the elastic and viscoelastic phase and by reducing the ability of the cuticle to deform. There seemed to be a negative relation between SlCHS expression and wax accumulation during ripening that could be related to the decreased cuticle permeability to water observed in the regions silencing SlCHS. A reduction in the overall number of ester linkages present in the cutin matrix was also dependent on the presence of flavonoids.

Transcriptional Activity of the MADS Box ARLEQUIN/TOMATO AGAMOUS-LIKE1 Gene Is Required for Cuticle Development of Tomato Fruit

“…polysaccharides, phenolics, and waxes) would explain the lower Young's modulus measured in TAGL1-repressed cuticles. This observation supports the results obtained in the cuticles of nor mutants and CHS-silenced tomatoes (Bargel and Neinhuis, 2004;España et al, 2014a).…”

“…Other transcription factors, such as SlMYB12 and NOR, have been shown to alter cuticle color during ripening due to a decrease in phenolics (Bargel and Neinhuis, 2004;Adato et al, 2009), but cuticle deposition was only affected by SlMYB12 (Adato et al, 2009). More recently, a significant decrease in cuticle and most of its components, except for waxes, was reported in tomato fruits silencing CHS during ripening (España et al, 2014a). The significant reduction in cuticle components known to confer stiffness (i.e.…”

Label‐free deep shotgun proteomics reveals protein dynamics during tomato fruit tissues development

“…One of the key steps of the flavonoid pathway in tomato fruit is the synthesis of naringenin chalcone from 4‐coumaroyl‐CoA, a reaction catalyzed by CHALCONE SYNTHASE (CHS; Muir et al ., ; Schijlen et al ., ). Two CHS genes ( CHS1 and CHS2 ) have been previously shown to be transcriptionally induced upon onset of fruit ripening (España et al ., ). Accordingly, abundance of these two proteins was induced in the fruit skin at the Br stage.…”

The Tomato MIXTA-like Transcription Factor Coordinates Fruit Epidermis Conical Cell Development and Cuticular Lipid Biosynthesis and Assembly

“…Recent results have indeed found that the fruit surface structure is influenced by cutin deposition; however, in this work, a change in cutin deposition was not necessarily shown to result in a change in epidermal cell shape (Petit et al, 2014). Furthermore, silencing of CHALCONE SYNTHASE expression (a gene responsible for the inclusion of naringenin chalcone in the tomato cuticle) results in a stiffer, less elastic cuticle surrounding flatter epidermal cells (Schijlen et al, 2007;España et al, 2014). These results hint at a potential dependence on the surrounding cuticle with regard to epidermal cell structure.…”