Carbon-11 Azelaic Acid as a Signaling Molecule for Mechanistic Studies in Plants
When a pathogen attacks a plant, the plant mounts an immune response that alerts the rest of the plant, a response called systemic acquired resistance (SAR). The chemical compound(s) responsible for inducing the immunity is a topic of intense interest for agriculture, including for bioenergy crops. For example, the application of a 9-carbon-atom-chain (C-9) dicarboxylic acid, azaleic acid, induces immunity, but the similar C-8 and C-10 diacids do not. One hypothesis is that the azaleic acid, but not the related acids, moves to distant parts of the plant. New radiochemistry imaging research at Brookhaven National Laboratory has developed a rapid method to label these three acids with Carbon-11 (11C, half-life of 20.4 min) for short-term (minutes to hours) tracking of their movement within the plant, and with Carbon-14 (14C, half-life of 5730 years) for long-term (hours to days) studies. When applied to a leaf, [11C]-azaleic acid shows substantial movement within an hour. When [14C]-azaleic acid is applied to the roots, it distributes throughout the whole plant within a day. These studies demonstrate that azaleic acid has the potential to be a mobile signaling molecule. The radioactive-carbon labeled diacids will have utility as scientific tools to unravel SAR mechanisms and other phenomena that impact production of robust bioenergy crops.
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