Structural puzzle on fruit skin

Cutin, a polyester of hydroxylated fatty acid and glycerol, has many functions for the plant (stress resistance, development, preservation, transformation). All these properties are linked to the structure of the polymer. In a previous study, the Biopolymers, Interactions, Assemblages (BIA) unit in Nantes demonstrated the first cutin polymerase (GDSL lipase) in tomatoes. Plants with different levels of expression of this protein have been generated (1).

From these plants, whose cutin is more or less polymerized, a BIA team has developed an original method for in situ labeling of ester bonds on tomato fruits. The team was then able to (i) reconstruct the structural puzzle of cutin and (ii) understand the activity of cutin polymerase in planta. The GDSL lipase determines the crosslinking scheme of the polymer by promoting the ester bonds of branched type. The water permeability properties of these more or less crosslinked cutins were compared. It appears that the thickness and not the degree of polymerization affects this permeability (2).

Partners: this work is the result of a collaboration between INRAE BIA (Nantes) and BPF (Bordeaux) and IZMB (University of Bonn, Germany).