Comparative evaluation of free and bound phenolic acid contents in early grains of durum wheat line for its resistance to fusarium head blight with some other sensitive varieties in Algeria

All plants contain varying levels of phenolic acids (metabolites) thus playing an important role in resistance mechanisms as constituents of cell walls, as constitutive antimicrobial compounds of plants or induced in response to infection against many diseases, in particular fusarium head blight caused by Fusarium species. To this end, the objective of this research was to study the variation in phenolic acid composition during the kinetics of filling wheat grains, in order to determine the best variety resistant to fusarium head blight. For this purpose, free and bound phenolic analyses were carried out by HPLC-DAD on five durum wheat varieties at the stage 5 to 8 days after the flowering stage (early grains). We showed that at the level of the samples analyzed, several phenolic acids were present at different concentrations, but others were absent [ cis-ferulic acid (free phenolic acid), and sinapic acid (bound phenolic acid)]. The results also showed that the content of bound phenolic acids was much higher than that of free phenolic acids in all varieties. In addition, these phenolic acids existed in free soluble form or were mostly present in insoluble form bound to cell walls. For free acids, the results showed that significant amounts of transferulic acid were detected in comparison to all free phenolic acids (56.72 μg · g –1 DM for G10). For bound acids, ferulic acid is the main bound phenolic acid which has much higher levels (4913.92 μg · g –1 DM for G1), followed by p-coumaric acid (3098.99 μg · g–1 DM for G1). Moreover, the sum of monomers (bound acids) was much higher than that of dehydrodiferulic acids (DiFA).