Characterization and Comparison of Expressed Genes Associated with Life Strategies in Tall Wheatgrass and Wheat

Characterization of expressed genes in perennial and annual grasses
Compared to annuals, perennial plants have developed more complex life strategies such as cold tolerance, overwintering buds and rejuvenating meristems, therefore, for the development of perennial wheat, a comprehensive characterization of the underlying mechanisms of the perennial habit is critical. In annual grasses, significant progress has been made towards understanding the flowering-time mechanism, including the characterization of major flowering genes, as compared to the understanding of flowering in perennial grasses. The focus of this research was to clone and characterize the major flowering-time genes in a close relative of wheat, the long lived perennial grass, Thinopyrum ponticum (tall wheatgrass) using annual cereal genes as templates. From a sequence perspective, the coding and 5’UTR regions of eight flowering-time genes in tall wheatgrass were similar to wheat with few nucleotide changes and no major alterations to the conserved functional domains. Using qPCR, expression of these genes was compared in tall wheatgrass and annual winter wheat (Norstar) over the course of eight developmental stages. This analysis showed several subtle differences in gene expression at critical developmental stages. An RNA-Seq experiment was completed using a subset of 24 meristematic and leaf tissue libraries at different developmental stages to further examine genes with similar expression patterns to known flowering-time genes. Numerous additional annotated genes were identified in different clusters supporting their contribution in different aspects of in the perennial habit that include vegetative and flowering stages and transition between them. This novel information is invaluable in understanding the role and regulation of different genetic elements in plant perenniality.