Mass Spectrometric Imaging of Glucosinolates in the Metal Hyperaccumulating Plant Noccaea Caerulescens.

The function of metals in metal hyperaccumulating plants has largely been ascribed to protection from insect herbivore attack. However, sulfur and nitrogen-containing glucosinolates are present in most hyperacumulators and are also involved in defense against insect herbivores. There is some evidence based on analyses of shoots and whole leaves that a trade-off exists in metal hyperaccumulating plants in which organic defenses are traded for metal defenses. However, there is little known about how this tradeoff occurs spatially within the leaf. Improving our understanding of why and how these tradeoffs occur can shed new light on the evolutionary reasons for the metal hyperaccumulating phenotype and the potential ecological consequences when using these plants for phytoremediation in non-native habitats. This system will be used as an example to demonstrate how imaging mass spectrometry (IMS) can be coupled with micro synchrotron x-ray fluorescence spectroscopy (micro-SXRF) and other techniques to illuminate the interaction between organic and inorganic defenses within single leaves of the Zn hyperaccumulator Noccaea caerulescense (alpine pennycress).