ABSTRACT
Many flowering plants have evolved diverse strategies to communicate with and attract animal pollinators. Compared to other plant families, unusual and/or highly specialized deceptive pollination strategies are particularly widespread in the hyperdiverse orchid lineage, yet the underlying molecular mechanisms remain largely unknown. We have discovered exciting new evidence for the role of anthocyanins and terpenes in the evolution of the highly diverse terrestrial orchid subtribe Caladeniinae (Diurideae). Our comprehensive approach, integrating floral anthocyanin and volatile profiling with phylotranscriptomics of 49 species spanning all major subgenera across the subtribe revealed that brightly-coloured (mostly pink, blue, purple) and strongly scented taxa that largely employ food deceptive (FD) pollination strategy are basal. Interestingly, the loss of terpene-rich floral volatiles underpins the emergence of two large radiation of > 250 sexually deceptive (SD) species (c. 10 - 5 Mya) that are typically dull-coloured (green/red) and employ sex pheromone mimicry of female insects. Arising out of these predominantly SD clades are several independent reversals to FD (c. 1 - 5 Mya) associated with the (re-)gain of terpenoid floral volatiles frequently observed in ancestral FD clades. We propose that the evolution of multiple deceptive pollination strategies in Caladeniinae was underpinned by two key mechanisms, operating both before and after a major paleoclimatic event (Middle Miocene Climatic Optimum, c. 18 – 14 Mya) that reshaped Australia's floristic community: 1) gene duplication and neofunctionalization of CYP75B, linked to the gain and loss of unusual floral color; and 2) interspecific variation in terpene synthase (TPS) gene expression, linked to the multiple gains and losses of terpene-rich volatile bouquets.

BIOGRAPHY

Darren is an upcoming Future Making Fellow at Adelaide University. His research focuses on the chemical and genetic basis of specialized metabolism involved in plant-biotic and plant-abiotic interactions. His research leverages cutting-edge genomics, transcriptomics, metabolomics, and integrative approaches to address the molecular mechanisms of floral color and scent changes underpinning pollination strategy shifts in Australian terrestrial orchids through to the transcriptional regulatory networks of plant biotic and abiotic stress responses in major horticultural crops. His work also extends to emerging ethnobotanicals, where his research has explored the biosynthesis of specialized metabolites for applications in fragrances, flavors, dyes/pigments, medicine, and biofuels. This is complemented by valuable industrial experience, including contributions to a Canadian multi-million-dollar biotech startup's cannabis R&D program for three consecutive years (2017 - 2020).