Across the plant kingdom, the jasmonate hormone steers the delicate balance between growth and the activation of defense programs, such as the production of bioactive specialized metabolites. Plant cells are capable of producing an overwhelming variety of specialized metabolites, both in terms of complexity and quantity. These small organic molecules allow plants to cope with various types of stresses but often also have biological activities of high interest to humans. Yet, this impressive metabolic machinery is still hardly exploited, mainly because of the limited molecular insights into plant specialized metabolism.

By using cutting-edge functional genomics tools, in combination with reverse genetics screenings, we try to identify the essential components acting in the jasmonate signalling network and to characterize the molecular mechanisms driving plant natural product biosynthesis in crop, medicinal and model plants. Besides increasing fundamental knowledge, our gene discoveries serve as a novel resource for (metabolic) engineering tools that will facilitate 1) the creation of a synthetic biology program for the sustainable production of high-value plant natural products and 2) increased crop productivity by improvement of plant growth and defense.

Unravelling Jasmonate Signalling Cascades

Jasmonates are plant-specific signalling molecules found throughout the plant kingdom that steer diverse physiological and developmental processes.

Their most well-known function is to signal attacks by arthropod herbivores or necrotrophic pathogens, both locally and systemically, leading to mounted defenses, including the activation of specialized metabolism. The central module of the jasmonate (JA) signalling cascade has largely been discovered in Arabidopsis thaliana, and found to be conserved across the plant kingdom. Bioactive JAs, such as jasmonoyl-isoleucine, are perceived by the E3 ubiquitin ligase SCFCOI1, which targets the JAZ repressor proteins for degradation. This event causes the release of the transcription factor MYC2, thereby activating the first wave of JA-induced gene expression. Within this cascade, the JAZ proteins play a central role. JAZ proteins have been demonstrated to interact with a broad array of transcription factors that each control specific downstream processes. Recruitment of the co-repressor TOPLESS unveiled a mechanism for JAZ-mediated gene repression. The presence of JAZ proteins was also found to be regulated by interactions with proteins from other hormonal signalling pathways, revealing modes of hormonal crosstalk.