Application of HERFD-XAS to study Cd speciation in cacao plant: Impact of metal deficiencies

The presence of cadmium in chocolate products raises health concerns for the general population. Mitigation strategies to reduce Cd in cacao beans are strongly needed for both socio economic reasons in cacao producing countries in Latin America and for health reasons. There is a large gap of knowledge on the pathways of Cd from the soil to the bean. An important information needed is where and how Cd is accumulated in the plant. We propose to use for the first time Cd L-edge HERFD-XAS to determine Cd speciation in cacao organs. We have exposed cacao clones at 100 nM Cd and various micronutrient (Mn, Zn, Fe) concentrations. Results will help to clarify the role of calcium oxalate crystals and the impact of micronutrient deficiency on Cd uptake and detoxification, and ultimately on Cd transfer to beans. Beside these results on Cd in cacao, this study will be a proof of concept for the interest of Cd L-edge HERFD-XAS for studies on cadmium in any domain, especially for biological samples.