Signalling role of Strigolactones at the interface between plants, (micro)organisms and a changing environment

Strigolactones (SLs) are a group of plant-exuded terpenoid lactones, initially known as the triggering signals for seed germination of parasitic weeds, and more recently for hyphal branching of arbuscular mycorrhizal fungi (AMF). In 2008 they were defined as a new class of plant hormones controlling plant architecture. Since then, great advances have been made on the biochemistry of SL biosynthesis and signal transduction, with several key genetic determinants now characterized. However, the complete pathway of de novo SL biosynthesis and transduction has not been firmly established yet. Recent findings have determined that beside shoot and root branching, SL-related components play essential roles in diverse processes including seed germination (for non-parasitic plants), hypocotyl elongation, reproductive development, leaf senescence and nodulation. In this update, we present an overview of the current knowledge on the SL biosynthetic pathway and perception/transduction mechanism. Then we highlight recent studies, which have delineated the functions of SLs in the interaction of plants with beneficial and parasitic (micro)organisms, and in the adaptive responses to a number of environmental stimuli.