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Registration of three blue-seeded wheat genetic stocks exhibiting xenia.

'Sebesta Blue-1' (Reg. no. GS-151, PI 634538), an awned soft winter wheat, 'Sebesta Blue-2' (Reg. no. GS-152, PI 634539), an awnless soft winter wheat, and 'Sebesta Blue-3' (Reg. no. GS-153, PI 634540), an awned hard spring wheat, are blue-seeded genetic stocks of Triticum aestivum L. which carry translocated segments of Thinopyrum A. Love chromosomes. All three lines are homozygous for the blue aleurone trait. In crosses with white- and red-seeded wheats, the blue aleurone trait exhibits a strong xenia effect, which is expressed in varying degrees from dark to light blue, depending on allelic dosage in the 3n endosperm. The Sebesta Blue (SB) genetic stocks were developed specifically for their use as genetic markers in the search for apomictic wheats. The proposed procedure for identifying apomictic wheats is outlined in Morrison et al. (2004). The name Sebesta Blue was selected to honor Dr. Emil Sebesta, the USDA-ARS wheat cytogeneticist at Oklahoma State University from 1958 to 1988, who produced the translocation lines that were used to develop these genetic stocks.

The pedigree of SB-1 and SB-2 is 'Gene' (PI 560129)/3/ 78xCi12/CS-Tsts3D//Gene and SB-3 is 78xCi6/2*Sonlika (CItr 15392). The lines 78xCi12 and 78xCi6 are Th. ponticum (Podp.) Barkworth & D.R. Dewey translocation lines developed by using irradiated pollen from blue-seeded plants from the cross 'Blue Baart'/'Norco' (Norco: CItr 14482) to pollinate emasculated spikes of the white-seeded, spring wheat 'Pavon 76' (PI 520003). Blue Baart is a disomic substitution line with the Th. ponticum translocation (Suneson, 1962). The line CSTsts3D is a white-seeded 'Chinese Spring' (CItr 14109) line carrying a 3D substitution from 'Timstein' (CItr 12347). The three SB germplasm lines were selected for blue aleurone and white pericarp seed traits over 20 generations of field testing in Oregon.

According to a preliminary sequential C-banding/FISH (fluorescence in-situ hybridization) analysis (Morrison et al., 2004), SB-3 (2n = 42) has a 4BS.4BL.4EL translocation. The Thinopyrum segment is large, occupying about two-thirds of the long arm of the chromosome. Karyotypes for the winter SB-1 and SB-2 lines (2n = 44) are problematic because Of numerous and as yet unidentified chromosomal rearrangements that have presumably been caused by irradiation. Two Thinopyrum translocations are present in SB-1 and SB-2. One of these appears identical to the 4EL segment identified in SB-3. Another small Th. ponticum segment is present on a miniature wheat chromosome that may be a part of 2D. It is likely that this extra chromosome pair has no relationship to the Thinopyrum 4EL chromosomal segment carrying the blue aleurone gene.

Despite their altered karyotypes, SB-1 and SB-2 act as stable blue-seeded marker lines. In successive generation testing, the blue aleurone trait does not segregate. In SB crosses to red- and white-seeded wheats, blue versus non-blue seed segregated 3 blue: 1 non-blue. In the case of the two winter lines, SB-1 and SB-2, there is some question as to their promise for open-pollination research. They both show a relatively low level of anther exsertion due to limited filament elongation and tendency of their florets to remain closed during anthesis. This cleistogamous trait has been observed under field and greenhouse conditions at Corvallis, OR, and should be evaluated in other environments as a trait that may limit pollen release into the air. In contrast, SB-3 anthers fully exsert in the Corvallis, OR, environment, thus allowing ample pollen release.

For blue-seeded lines with a weak xenia expression, detection of the blue-aleurone marker can be problematic, especially at the one-dose level (Knott, 1958). In the case of the SB genetic stocks, the blue marker trait is strongly expressed and is clearly visible in one allelic dose. For wide interspecific crosses, particularly with dark, red-seeded species, presence of the blue marker is more easily determined in plump rather than thin seeds.

Voucher specimens of the SB lines are deposited in the OSU and Smithsonian Institute (US) Herbaria. Appropriate recognition of the source should be noted if these genetic stocks contribute to the development of new cultivars, research lines, genetic stocks, and germplasm. Recognition of the source also should be noted for any genetic marker research using the SB lines, or any of their preregistered forms distributed before 2003. Seed increases from preregistered forms are limited to distribution for research purposes only and require appropriate recognition as described above.

References

Knott, D.R. 1958. The inheritance in wheat of a blue endosperm color derived from Agropyron elongatum. Can. J. Bot. 36:571-574.

Morrison, L.A., R.J. Metzger, and A.J. Lukaszewski. 2004. Origin of the blue-aleurone gene in 'Sebesta Blue' wheat genetic stocks and a protocol for its use in apomixis screening. Crop Sci. 44:2063-2067 (this issue).

Suneson, C.A. 1962. Use of Pugsley's sterile wheat in cross breeding. Crop Sci. 2:534-535.

R.J. METZGER * AND E. SEBESTA

R.J. Metzger, Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331-3002; E. Sebesta, Dep. of Plant and Soil Sciences, Oklahoma St. Univ., Stillwater, OK 74078 (now deceased). Accepted 30 April 2004. * Corresponding author (R.J. Metzger via mark.larson@oregonstate.edu).

Published in Crop Sci. 44:2281-2282 (2004).
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Title Annotation:Registrations Of Genetic Stocks
Author:Metzger, R.J.; Sebesta, E.
Publication:Crop Science
Date:Nov 1, 2004
Words:849
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