Improved localization and speciation of Cd in cacao plant: Impact of Mn deficiency

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. We wish to clarify the role of calcium oxalate crystals and mucilage cavities and the impact of Mn deficiency on Cd uptake and detoxification. We have exposed cacao clones to 100 nM Cd, a realistic concentration, and normal and deficient Mn concentration. We propose to couple µXRF and Cd L-edge µXANES at ID21 to determine Cd distribution and speciation in cacao organs. Preliminary tests on the new nanoSXM show a breakthrough in terms of image resolution, XAS spectral quality, acquisition speed and sample preservation compared to the micro station. This will be the first synchrotron study on cacao clones in controlled conditions.