Title : Beyond Arabidopsis: Paving the Way to Commercial Applications of Karrikin Compounds
Abstract:
Karrikins are a family of compounds derived from charred plant materials and smoke that were discovered in 2004 as the chemical cues that stimulate germination from seed banks for many fire-following species. The most universally active and abundant compound from smoke, karrikinolide or KAR1, was chemically synthesised in 2005 and subsequent research has determined that the karrikin perception system is fundamental in plant functioning throughout many angiosperms, including non-fire following plant species. Nonetheless, most of the recent work into karrikin functioning in plants has used the model plant Arabidopsis thaliana. Beyond seed germination stimulation, the proposed karrikin signal transduction mechanism in Arabidopsis can increase a seed’s sensitivity to light, enhance seedling photomorphogenesis and accelerate leaf morphogenesis. Additionally, the very recent discovery in Arabidopsis that karrikins may behave as microprotectants, potentially having an important role in improving plant resilience to abiotic stress, makes karrikin research timely and suggests that crops could especially benefit from applications of this compound. Escalating climatic extremes are already making many crop varieties struggle to thrive under increasingly challenging abiotic conditions, such as heat waves and drought, but there is only limited evidence to suggest that karrikin effects in Arabidopsis translate to crop species, either under stressful or non-stressful conditions. Hence here we show a systematic approach to further karrikin research so these compounds can become useable for crops under field conditions and for other plant-related applications. Specifically, we use crops from the Solanaceae family to demonstrate a family-specific active dosage for karrikin compounds while concomitantly showing intra-specific variation for the magnitude of the karrikin response. Thus our results suggest that different varieties within a single crop are likely to require screening to determine their karrikin activity and for this we provide a simple laboratory method to screen for active dosages. For both KAR1 and KAR2, administered via seed priming, active dosages from laboratory assays are shown to effectively modify the plant phenotype and morphological characteristics until harvest. Thus this work provides a structured approach to further karrikin research, paving the way to making karrikin compounds useable for commercial plant applications.
