Phenolic compounds involved in pine wilt disease: HPLC-based method development and validation for their quantification

Pine Wilt Disease, caused by the pine wood nematode, is a severe and unsolved sanitary problem of pine forests in Europe and Eastern Asia. However, not all Pinus species are affected. Differences in their phenolic pattern may imply different resistance/susceptibility to the nematode, but this topic has not yet been investigated in detail. Therefore, a thorough analysis of phenolic compounds in different Pinus species is crucial to assess their role as markers of resistance/susceptibility to the nematode in order to understand the defense mechanisms against it, and to develop innovative strategies to manage and control wilt disease. A HPLC-based method for the simultaneous quantification of gallic acid, ferulic acid, epicatechin, taxifolin, rutin, resveratrol and secoisolariciresinol in Pinus tissues was developed and validated. The method exhibits good sensitivity, low limits of detection and quantification, good precision, and high specificity and selectivity. The method was successfully applied to the quantification of the above-mentioned phenolic compounds in thirty-six extracts of Pinus halepensis and Pinus sylvestris tissues, before and after nematode inoculation. The results showed that the studied compounds can act as potential interspecific markers of resistance/susceptibility to the pathogen. Hence, the method lends itself readily for application in scientific studies and routine analysis on this sanitary issue.