Plant cutin genesis: unanswered questions

•Recent advances improved our understanding of how biopolyester cutin is constructed; two main approaches have been reported, as follows.•Cutin is polymerized by specific extracellular acyltransferase enzymes.•Cutin is the final result of a nonprotein extracellular self-assembly process of its monomers.•Both models still need further development and improvement, as critically described in this review.

The genesis of cutin, the main lipid polymer present in the biosphere, has remained elusive for many years. Recently, two main approaches have attempted to explain the process of cutin polymerization. One describes the existence of an acyltransferase cutin synthase enzyme that links activated monomers of cutin in the outer cell wall, while the other shows that plant cutin is the final result of an extracellular nonenzymatic self-assembly and polymerizing process of cutin monomers. In this opinion article, we explain both models and suggest that they could be pieces of a more complex biological scenario. We also highlight their different characteristics and current limitations, and suggest a potential synergism of both hypotheses.