Identification and Characterization of Flowering Time Genes in Tall Wheatgrass.

Tall wheatgrass, Thinopyrum elongatum (2n=2x=14) and Th. ponticum (2n=10x=70), are long lived perennial grasses closely related to wheat. Economically, tall wheatgrass is an important source of forage. From a sustainable production system development perspective, tall wheatgrass provides an important source of perennial habit for the development of perennial wheat. In general, the molecular pathways controlling flowering in perennial wheatgrasses is at best poorly understood. Regulation of flowering and perennial habit is a complex trait involving many genes. However significant steps in understanding flowering and life history in perennial members of the Brassica’s have been made and in combination with knowledge of flowering genes in wheat, we have initiated the identification, sequencing and characterization of the expression profile of the homeologous genes possibly responsible for flowering and the perennial habit in tall wheatgrass. To begin to elucidate the genetic mechanisms and pathways for flowering and perennial growth habit, we cloned, based on wheat sequence homology, the full length sequences of eight candidate genes (VRN1, VRN2, VRN3, FDL2, Ppd-1, TFL, CO and GI) in two accessions of Th. elongatum and two accessions of Th.ponticum and compared the sequence composition to that of Triticum aestivum (cv. Chinese Spring). Furthermore, we have generated information on the 5’ non-translated region of these genes by rapid amplification of cDNA ends (RACE) PCR and we are comparing the introns of corresponding genomic sequences. We will report on the gene specific indel differences within the four Thinopyrum accessions and Triticum aestivum. The potential impact on functionality of these altered sequences will be presented. Our sequencing data combined with our future work in stage-specific gene expression profiles and virus-induced gene silencing of these cloned genes will enhance better understanding of the perennial growth habit in wheatgrass with the potential to accelerate the development of perennial wheat.