Aegilops cylindrica Host (jointed goatgrass) is an exotic invasive weed in the western United States that causes economic loss due to competition with winter wheat (Triticum aestivum L.) and contamination of wheat grain. Further, because Ae. cylindrica is a wild relative of wheat, interspecific hybridization is a possible mechanism for the introgression of advantageous genes from wheat to the weedy species. The risk of introgression of traits conferring environmental stress tolerance, such as drought tolerance, from transgenic wheat has not been studied and is of high concern because it could increase the weed's competitiveness with wheat, as well as its ability to invade novel habitats. Genetic diversity has been reported among western U.S. Ae. cylindrica accessions, however, studies to determine whether genetic diversity relates to phenotypic diversity have been limited. Here, 30 accessions of Ae. cylindrica from the western U.S. were evaluated over two years at two Colorado locations: Haxtun in 2008-2009 and Fort Collins in 2009-2010. Days to flowering, plant height, number of tillers produced per plant, number of spikelets per spike, and number of spikelets per plant were evaluated under rain-fed and irrigated conditions. Results indicate significant (P<0.01) variation among accessions for each of the traits for both years. Additionally, in 2009-2010 there was a significant (P<0.01) effect of irrigation on all traits, except days to flowering. Similarly, all traits except days to flowering showed a significant effect of the interaction of accession with treatment (P<0.05) in 2009-2010. The study shows that variation exists in traits related to competitive ability and fitness. Our data also suggest differences among accessions in sensitivity to water availability. This observation needs to be confirmed in additional environments. Implications of our results for evaluation of transgene introgression are discussed. (C) 2012 Elsevier B.V. All rights reserved.
