Transport of defense compounds from source to sink: lessons learned from glucosinolates

Plants synthesize a plethora of defense compounds crucial for their survival in a challenging and changing environment. Transport processes are important for shaping the distribution pattern of defense compounds, albeit focus hitherto has been mostly on their biosynthetic pathways. A recent identification of two glucosinolate transporters represents a breakthrough in our understanding of glucosinolate transport in Arabidopsis and has advanced knowledge in transport of defense compounds. In this review, we discuss the role of the glucosinolate transporters in establishing dynamic glucosinolate distribution patterns and source-sink relations. We focus on lessons learned from glucosinolate transport that may apply to transport of other defense compounds and discuss future avenues in the emerging field of defense compound transport.