Apports des techniques spectroscopiques en biologie végétale

Abstract

International audienceAlthough spectroscopic techniques based on very large research infrastructures are commonly used in disciplines such as physics or material sciences, they are less common among plant biologists. However, they give access to information that can greatly advance our understanding of biological mechanisms. Micro X-ray fluorescence micro-spectroscopy (μXRF) based on synchrotron radiation makes it possible to obtain elemental distribution maps with a lateral resolution down to submicrometer scale and high sensitivity. In compliment to μXRF, some synchrotron beamlines have the capability to perform micro-X-ray absorption spectroscopy (µXAS) analysis. This technique allows to probe the local structure of the element of interest and to determine its oxidation state and its ligands. This is for example very useful in ecotoxicology to understand the behavior and fate of a contaminant to better evaluate its bioavailability and possible impacts on the environment. Alternatively, in agronomy this information can be used to improve plant nutrition. These techniques are, however, extremely dependent on a proper sample preparation. For about ten years, much progress has been made both on the equipment of synchrotron beamlines and on the sample preparation techniques to take into account the particular nature of biological samples (highly hydrated, fragile and sensitive to radiation). These different points will be developed through the example of plants (Lactuca sativa, lettuce) exposed to a foliar iron salt supply and addition of silver nanoparticles