A matter of smell: The complex regulation of aroma production in melon.

Melon fruit flavor is one of the most valuable traits for consumers. Aroma, formed by volatile organic compounds (VOCs), is a major component of flavor but has been neglected in breeding programs because of its complex regulation. Although the genetic regulation of VOCs biosynthesis is not fully understood, several advances have been recently achieved. VOCs originate from the degradation of fatty acids, aminoacids and terpenes, and the role of newly described enzymes, transcription factors and putative regulators is here discussed. Furthermore, ethylene plays a key role in fruit aroma production in melon, triggering the conversion of green-flavored aldehydes into fruity-flavored esters. A current challenge is to understand the ethylene-independent regulation of VOCs formation. Environmental conditions and human processing can also shape the melon volatile profile, and future research should focus on studying the effect of climate change in aroma formation.