David Cahill1, Chi T. L. Tran1,, Tejaswini Patlolla1, Md Tohidul Islam1, Damien Callahan2, Tony Arioli1,3
1 Deakin University, Geelong Waurn Ponds Campus, School of Life and Environmental Sciences, Victoria 3216, Australia
2 Deakin University, Burwood Campus, School of Life and Environmental Sciences, Centre for Cellular and Molecular Biology, Victoria 3125, Australia
3 Seasol International, Bayswater, Victoria 3153, Australia
The ‘Omics’ era presents us with an unparalleled opportunity to undertake deep analyses of the actions and functions of seaweed-derived biostimulants. Our recent work on transcriptomic and metabolomic analyses of plant responses to application of brown algal extracts has revealed an intricately complex mode of interaction. In particular, our discovery of priming or ‘ready for action’ induction following application of these extracts means plants are better able to respond to stress. We have used extracts derived from the brown algae, Ascophyllum nodosum and Durvillaea potatorum in studies on the model plant, Arabidopsis thaliana, and the horticultural species, Solanum lycopersicum (tomato) and Castanea sativa (sweet chestnut) to explore priming with or without infection by the pathogens, Phytophthora cinnamomi and Gnomoniopsis smithogylvii. We have shown a strong priming response following seaweed-extract application that included the upregulation of reactive oxygen species that are required for many important signalling reactions. Priming and defence priming-related genes were also upregulated prior to pathogen infection. Coupled with the striking upregulation of major genes related to plant defence such as the ‘pathogenesis related’ (PR) genes we found key metabolites such as the phytohormones salicylic acid and jasmonic acid and those related to primary and secondary metabolism to be increased in abundance following extract treatment. Further, the finding that seaweed extracts stimulate gene activity and metabolite production in Arabidopsis related to both photosynthesis and energy production, presents a platform of induced change that can be manipulated in crop species for stress resilience, enhanced growth and a boost in productivity.