RocheH 454 GS FLX Titanium is a high throughput sequencing platform that makes it possible to generate massive amounts of information in a short period of time with unprecedented high sequencing depth and low cost. The generated expressed sequenced tags databases are invaluable for gene mining and annotation, phylogenetic analysis, molecular markers and expression analysis. Given the status of A. planipennis as an aggressive killer of NA ash trees, we undertook a functional genomics approach to identify the repertoire of genes expressed in phloem tissue of different ash species including green, white, black, blue, and Manchurian ash. This study will OSI-774 enable us to identify genes that are potentially involved in A. planipennis resistance of Manchurian ash, and to characterize the genetic makeup of ash phloem for future studies. Results stemming from this study could be used in future ash targeted breeding programs and increase fundamental understanding of interaction between ash trees and wood-borers such as A. planipennis. In this study, we recovered a high number of transcripts that were mapped to the phenylpropanoid biosynthesis pathway. This pathway leads to the production of several phenolic compounds that plays an important role in plant defense against herbivores, microbes, and wounding. Although not all of the major genes reported in the pathway were found in this study, this information provides a good base for further CYT387 analysis and to better understand the potential role of phenylpropanoids in ash defense against biotic stress. The utilization of second generation sequencing for ash species has revealed various metabolic pathways that are of high interest with respect to ash resistance to A. planipennis. Data pertaining to the constitutive expression levels of early gene regulators in different ash species, revealed higher levels in Manchurian ash compared to NA ash. Results obtained in this study will lay the foundation for future differential gene expression analysis among different ash species and in deciphering the pathways of secondary metabolism which is related to plant defense. Molecular markers predicted in the current study will further help in population genomics and gene based association studies. These studies will provide critical insights to develop NA ash species that are resistant to A. planipennis through breeding programs and/or the application of transgenic technology.