Unfolding the potential of alpine pennycress for nickel agromining

Noccaea caerulescens (alpine pennycress) is a hyperaccumulator of zinc, also known to hyperaccumulate nickel in ultramafic soils. Alpine pennycress is a perennial plant from the family Brassicaceae, native to Europe, with patchy distribution from the United Kingdom and France to Slovakia and from Germany and Poland southward to northern Spain and Italy. In Scotland, it can be found in different locations, including ultramafic outcrops in the Cairngorms, Ayrshire, and the Isle of Rum. Ultramafic (or serpentine) soils are naturally occurring metalliferous soils that are typically enriched in nickel, chromium, and cobalt, and are deficient in essential nutrients and organic matter, making them unappealing for conventional agriculture. Ultramafic soils are widespread around the world and harbour an elevated number of nickel hyperaccumulators (>500 identified to date). Hence, ultramafic soils are particularly interesting for agromining (or phytomining), a plant-based technique for the recovery of valuable elements, such as nickel, from metal-rich soils. Agromining relies on the ability of hyperaccumulators to uptake extraordinary amounts of the target metal into their shoots, which are then harvested and incinerated to produce a bio-ore. Although significant progress has been made over the past two decades, nickel agromining remains an infant technology with plenty of room for improvement. In this light, assessing the potential of symbiotic microorganisms (e.g., mycorrhizal fungi, plant growth-promoting rhizobacteria), climate-friendly soil amendments (e.g., biochar), phytohormones, and sustainable chelating agents will be crucial to achieve further breakthroughs, enabling commercial-scale nickel agromining operations.
This project offers an exciting opportunity to work at the nexus of plant physiology, soil science, microbiology, and biogeochemistry to advance a promising resource recovery green technology. The doctoral candidate will investigate the nickel uptake ability of different alpine pennycress ecotypes and determine the effect of microbial inoculation, biochar, phytohormones, and low molecular weight organic acids in the overall agromining process. The student will engage in significant field and laboratory work, and will receive cross-disciplinary training (e.g., study of plant physiological and biochemical traits, soil physicochemical characterisation, elemental analysis via inductively coupled plasma mass spectrometry and X-ray fluorescence spectrometry, and isolation, identification, and culture of symbiotic microorganisms). The research will also provide valuable knowledge on the underlying mechanisms of phytoremediation. Publication of the results in peer-reviewed journals and presentation of the main findings in local and international scientific events are envisaged. The work will be carried out at Scotland's Rural College and the School of Geosciences of the University of Edinburgh.