Transcriptome analysis of constitutive resistance to white pine weevil in Picea glauca-engelmannii (Interior spruce)

White pine weevil is a major pest of conifers in North America, especially for Spruce trees. Constitutive defenses are important in understanding defense mechanisms because they constitute the initial barrier to attacks by weevils and other pests. Resistant and susceptible trees exhibit constitutive differences in spruce. To improve our knowledge of their genetic basis, we compared the constitutive expression levels of 17,825 genes between 20 resistant and 20 susceptible trees in interior spruce (Picea glauca). Twenty hybridizations were performed to compare untreated bark of resistant and susceptible trees.RNA isolated from each of the 20 individual untreated resistant trees was compared directly against the 20 individual untreated susceptble trees using two hybridizations with a dye flip for each tree pair.