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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic Improvement of Durum and Spring Wheat for Quality and Resistance to Diseases and Pests

Location: Cereal Crops Research

Title: Synthetic hexaploids derived from under-exploited tetraploids as a new resource for disease resistance in wheat

Authors
item Xu, Steven
item Zhang, Q -
item Jin, Yue
item Rouse, Matthew
item Liu, Zhaohui -
item Friesen, Timothy
item Pumphrey, Michael
item Cai, Xiwen -
item Faris, Justin

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2013
Publication Date: September 7, 2013
Citation: Xu, S.S., Zhang, Q.J., Jin, Y., Rouse, M.N., Liu, Z.H., Friesen, T.L., Pumphrey, M.O., Cai, X., Faris, J.D. 2013. Synthetic hexaploids derived from under-exploited tetraploids as a new resource for disease resistance in wheat. 12th International Wheat Genetics Symposium, September 8-14, 2013, Yokohama, Japan. p. 107.

Technical Abstract: Synthetic hexaploid wheat (SHW) (2n = 6x = 42, genome AABBDD), which is developed from the hybridization between tetraploid wheat (Triticum turgidum L., 2n = 4x = 28, genome AABB) and Aegilops tauschii Coss. (2n = 2x = 14, genome DD), is a useful bridging germplasm for the introgression of desirable genes from both tetraploid wheat and Ae. tauschii into hexaploid wheat (T. aestivum L.). Most previous SHW production programs have focused on utilization of durum wheat (T. turgidum ssp. durum) as the AB genome donor to incorporate genetic variation in Ae. tauschii collections. However, the genetic diversity in other tetraploid subspecies has not been widely exploited through the SHW approach. The objectives of this study were to develop new SHW lines with an emphasis on pest resistance derived from tetraploid subspecies other than durum wheat and then to characterize the expression of pest resistance at the hexaploid level. Based on the characterization of a large number of accessions among six tetraploid subspecies (T. turgidum ssp. carthlicum, T. turgidum ssp. dicoccum, T. turgidum ssp. dicoccoides, T. turgidum ssp. polonicum, T. turgidum ssp. turgidum, and T. turgidum ssp. turanicum) for resistance to major wheat diseases (Fusarium head blight, stem rust, leaf rust, and stripe rust, tan spot, and Stagonospora nodorum blotch) in separate experiments, we selected 181 unique tetraploid genotypes from the six subspecies and four durum lines for crosses with 14 Ae. tauschii accessions. A set of 200 SHW lines have been developed from these crosses. Except for a few lines showing hybrid chlorosis, most of the SHW lines had normal growth and fertility. The evaluation and characterization of these new SHW lines for resistance to major diseases and for other traits is currently underway. So far, 80 of the SHW lines along with the corresponding tetraploid and Ae. tauschii parents have been evaluated with the three most virulent races (TTTTF, TTKSK, and TRTTF) of the stem rust pathogen, two races (Pstv-11 and Pstv-51) of the stripe rust pathogen, three races (1, 3 and 5) of the tan spot pathogen, and one isolate (Sn2K) of Stagonospora nodorum blotch (SNB). Stem rust assays revealed that 52, 42, and 40 SHW lines were resistant to races TTTTF, TTKSK, and TRTTF, respectively, with 21 lines being resistant to all three races. We identified six and two SHW lines with resistance to stripe rust races Pstv-11 and Pstv-51, respectively, and 32 SHW lines with resistance to both tan spot and SNB. Comparative analysis of individual SHW lines and their parents indicated that suppression of stem rust resistance derived from tetraploid wheat was common in the SHW lines, while increased levels of resistance to tan spot and SNB were prevalent in the SHW lines compared with their tetraploid parents. The new SHW lines carrying unique resistance genes from the tetraploid accessions represent a new resource for hexaploid wheat improvement. In addition, these materials are invaluable for investigating polyploidization, genome evolution, and intergenomic interactions in wheat.

Last Modified: 8/21/2014
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