One of the biggest challenges to a more widespread utilization of natural fibers from flax and other fiber plants is to obtain a better understanding of the different factors underlying the observed variability in fiber quality. To do this, we measured fiber morphometric parameters from seven different flax varieties (4 spring fiber, 2 winter fiber and 1 winter oil) and undertook Partial Least-Squares Discriminant Analysis (sPLS-DA) of transcriptomic data obtained from the same varieties in an attempt to identify high-information molecular markers. The calculation of Pearson correlation coefficients identified 5 putative gene-markers strongly correlated with morphometric features. Proteomic analysis on the two varieties showing the most discriminant and significant differences regarding to morphometrics identified an additional 4 protein-markers. The majority of the obtained markers are involved in lipid metabolism and the senescence process. Further comparative analysis of the obtained expression data with fiber mechanical measurements (strength, maximum force, area) obtained after field-retting for all 7 varieties allowed us to identify 4 highly-correlated putative molecular markers for the mechanical parameters. Three genes, connected directly or indirectly to cell wall metabolism (Expansin-related protein 3 precursor, beta-glucosidase and ascorbate peroxidase), and one gene coding an enzyme that catalyzes the oxidative decarboxylation of L-malate (NADP-malic enzyme 3). Based on our results, we hypothesize that a reduced number of RNA and protein functional markers can be used to more accurately monitor and/or predict fiber yield and quality properties in different flax varieties, thereby contributing to an Agriculture 4.0 for this economically-important species.