Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/20/2007
Publication Date: 12/1/2007
Citation: Gu, X., Ren, S., Chu, C., Glover, K., Xu, S.S., Faris, J.D., Friesen, T.L., Ibrahim, A. 2007. Identification of seed dormancy for four populations derived from synthetic hexaploid wheat. Plant and Animal Genome Conference. December 1-2, 2007 Kansas City MO. Interpretive Summary:
Technical Abstract: Seed dormancy is a key adaptive trait for wild species and is also a major domestication-related trait for crop species. Cereal cultivars have been selected for rapid, uniform germination during domestication and breeding and consequently, they generally have an insufficient degree of seed dormancy to resist pre-harvest sprouting (PHS). To seek dormancy genes from the wheat wild relative Aegilops tauschii, we have identified four populations of doubled haploid (DH) or recombinant inbred (RI) lines derived from synthetic hexaploid wheat (SHW). The four populations, coded as DH1, DH2, DH3, and RI1, were developed from crosses between different SHW lines and the non-dormant line ND495. Plants were grown in field conditions in the summers of 2006 and 2007; seeds/panicles were harvested at the physiological maturation stage, air-dried in a greenhouse for 7 days, and then stored in the cold room (5'C) prior to dormancy testing. Degree of dormancy was measured by germinating threshed seeds (refer to threshed seed germination) and seeds on the intact panicles (refer to intact seed germination) at 20'C. Threshed seed germination for the DH1, DH2, DH3, and RI1 populations were 46.0 ± 23.9, 77.7 ± 16.5, 95.6 ± 7.4, and 66.7 ± 24.0 (%), respectively after 7-day incubation, and 55.8 ± 22.2, 82.7 ± 13.6, 97.7 ± 4.3, and 68.0 ± 23.0 (%), respectively after 14-day incubation. An overwhelming majority of lines from the populations displayed stronger dormancy with the threshed seeds than the non-dormant parent ND495 (germination rate greater than 93%) under the same condition. In a preliminary experiment, a subpopulation of 60 lines from the DH1 population harvested in 2007 displayed 39.9 ± 26.2 and 27.5 ± 27.5 (%), respectively for threshed and intact seed germination after 10-day incubation, and the threshed and intact seed germinations were highly correlated (r = 0.784 or r2 = 0.61). The above results suggest Ae. tauschii-derived synthetic hexaploid wheat could be a novel source of seed dormancy genes imparting resistance of common wheat to PHS, and the covering tissues in the synthetic wheat-derived lines may also have germination inhibitors enhancing PHS resistance. We are using a QTL analysis strategy to identify dormancy genes from the above populations.