Apocarotenoid signals in plant development and beyond

Carotenoids are much more than the familiar yellow-to-red pigments that we find in fruits and flowers. Arguably it is the products of carotenoid breakdown"”the apocarotenoids"”that are most diverse in terms of chemical structure and biological function. The hydrocarbon backbone presents a wide variety of positions for oxidative cleavage and chemical modification to produce compounds that serve as hormones, volatile aromas, and intracellular secondary messengers. In this Special Issue, we present a collection of articles that discuss the production, diversity, and function of apocarotenoids and related compounds, particularly as plant growth regulators and as rhizospheric signalling molecules.