Abstract text: p-Coumaroyl-CoA:monolignol transferase has been shown to participate in lignin coumaroylation in Brachypodium distachyon. However, the precise localization of these acylations at tissue and cell wall levels remains poorly characterized. Detecting compounds that may represent less than 1% of the cell wall is challenging, particularly when specific antibodies are unavailable.
In this study, fluorescence microscopy approaches, including large-beam excitation scanning at the SOLEIL synchrotron, were used to identify variations in hydroxycinnamic acids within Brachypodium distachyon stems. Principal Component Analysis (PCA) applied to fluorescence images successfully discriminated genotypes with subtle differences in phenolic composition.
These observations were supported by immunolabeling, showing that p-coumarate co-localizes with S-unit lignin in lignified tissues, whereas ferulate displays a broader distribution, sometimes in unexpected area. Overall, autofluorescence imaging combined with PCA provides a robust, non-destructive approach to visualize lignin and phenolic compounds, offering new insights into cell wall specialization and the roles of phenolics.