Gene Expression Analysis Of Wooden Breast Disease In Three Distinct Modern Broiler Lines

Wooden Breast Disease (WBD) is a relatively new muscle disorder known to affect the pectoral muscles in modern broiler chickens raised under modern commercial conditions. This disorder significantly decreases meat quality resulting in substantial economic losses in the poultry industry. To establish the molecular profile associated with this disorder, we compared gene expression profiles between affected and unaffected birds from 2 purebred lines and one crossbred commercial broiler (CB) population. Breast muscle samples were taken from affected and unaffected birds at day 47 or 48 post-hatch and subsequently processed for RNA-seq analysis using the Ilumina Hiseq platform. The numbers of differentially expressed (DE) genes at >1.3 fold change (FC) with a false discovery rate (FDR) of <0.05 between affected and unaffected birds in lines 1, 2 and CB were 3854, 3119 and 3682, respectively. 1328 genes out of all DE genes overlapped and exhibited the same expression direction in all three populations. A comparative analysis of all DE genes using Ingenuity Pathways Analysis (IPA^®) revealed 47 canonical pathways with relatively consistent Z-scores across three populations. The same presentation was also reflected on upstream regulators. The top canonical pathways such as RhoA signaling and upstream regulators such as TGFβ1 were activated in affected chickens. Based on the relative similarities of molecular and biological processes in the three distinct broiler populations, the present study demonstrates the existence of a unique gene expression signature for this disorder, which could aid in diagnosis of WBD as well as in understanding its cause and pathogenesis.