Format: ORAL

Sandrine Isnard 1, Kathryn M. Spiers2, Tanguy Jaffr1.3, Dennis Brueckner2, Sarah C. Irvin4, Jan Garrevoet4, Peter D. Erskine5, Vidiro Gei5, Emmanuelle Montargs-Pelletier6, Bruno Fogliani7, Guillaume Echevarria8, Antony van der En8,9

1AMAP, Université Montpellier, IRD, CIRAD, CNRS, INRAE, Montpellier, France 2Deutsches Elektronen-Synchrotron DESY, Germany. 3AMAP, IRD, Herbier de Nouvelle-Calédonie, Nouméa, New Caledonia 4Helmholtz-Zentrum Hereon GmbH, Germany. 5Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, Australia. 6Laboratoire Interdisciplinaire des Environnements Continentaux, CNRS, Université de Lorraine, France. 7Institut Agronomique néo-Calédonien (IAC), Equipe ARBOREAL (AgricultuRe BiOdiveRsité Et vAlorisation), New Caledonia. 8Université de Lorraine, INRAE, LSE, F-54000, Nancy, France. 9Laboratory of Genetics, Wageningen University and Research, The Netherlands.

Following the discovery of hyperaccumulation syndrome, numerous species were discovered, of which Ni-hyperaccumulators are by far the most numerous. Over 400 plant species are currently known to be nickel hyperaccumulators, and about a quarter of this diversity is found in New Caledonia. The extremely high Ni concentrations found in hyperaccumulator species raise the question of how plants can survive with such high metal content in their cells, and how does plant diversity translate into Ni-location strategy within the plant. At particular, the exact localization of metal within the leaf is of central significance because it might interfere with metabolic process such as photosynthesis. In this talk, we will present our current knowledge of Ni distribution in hyperaccumulators tropical plant species from New Caledonia, based on synchrotron elemental imaging. We will then make of focus on Ni-enriched laticifer in the model species Pycnandra acuminata to bridge the gap between the structure and function of laticifers in metal accumulation. The extraordinarily high nickel concentrations in this species function as an effective natural tracer for both synchrotron-based X-ray fluorescence microtomography and phase contrast microtomography, allowing non-destructive probing of the structure and the physiological functioning of this unique duct system. Using fresh plant samples, we combined analysis with these techniques to visualize intact laticifers in vivo for the first time and further, to provide unprecedented insights in the distribution and structure of laticifers throughout the plant, from roots to leaves. Considering that laticifers extend from root-to-shoot, our study elicits the hypothesis that the laticifers network constitute an independent ion transport system, which would establish a new paradigm in long distance transport in plants.