A comprehensive review of the chemical composition and epicuticular wax morphology of the cuticle in Sapindales

Cuticular waxes play an important role in plant survival in terrestrial environments. They are part of the cuticle and form a hydrophobic barrier associated with a decline in water loss through cuticular transpiration. Data on the chemical and morphological composition of cuticular waxes in Sapindales have been collected for more than 5th years. The present review compiles the data published for the species of this order between 1970 and February of 2021 on the Google Scholar and Web of Science databases. From the 55 papers, more than a third (36.4%) are related to chemical composition analysis and morphological description of epicuticular waxes on leaves and fruits. However, other aspects studied include wax variation during development (27.3%) and the interactions between the cuticle, microorganisms and pathogens (5.5%). Alkanes, free fatty acids, primary alcohols, ketones and triterpenes are the main classes of wax components, with homologue distribution similar to that described for other angiosperm. Amorphous epicuticular waxes were predominant on the leaves and fruits, mainly the smooth layer type. On stems, crystalloid platelet and rodlet morphologies were the most common. The presence of uncommon compounds in some species reinforces the considerable unexplored potential of this group of plants.