Registration of Four Durum Germplasms Carrying Glutenin Allele Glu‐D1d on a 1AS.1AL‐1DL Translocation Chromosome

Four durum (Triticum turgidum L. var. durum) germplasms carrying Glu-D1d on a 1AS.1AL-1DL translocation chromosome have been released in October 2004 by the USDA-ARS Northern Crops Science Laboratory, Fargo, ND, and North Dakota State University. The germplasms are identified as L092 (Reg. no. GP-796, PI 636498), L252 (Reg. no. GP-797, PI 636499), S99B33 (Reg. no. GP-798, PI 636500), and S99B34 (Reg. no. GP-799, PI 636501). The gene Glu-D1d encodes for high molecular weight (HMW) glutenin subunits 1Dx5 and 1Dy10 (5110) (Payne and Lawrence, 1983); and these subunits are highly desirable for superior bread-baking quality. The germplasms were produced in an effort to develop dualpurpose (good pasta and bread-baking quality) durum wheats. The crosses used for developing the germplasms were made by Joppa et al. (1998). TheGlu-D1d allele was transferred from the hexaploid wheat ‘Len’ (CItr17790) to a tetraploid background by crossing to Langdon 1D(1A) and backcrossing to ‘Langdon’ (CItr13165). Langdon 1D(1A) is an aneuploid stock of Langdon in which chromosome 1D from common wheat Chinese Spring (CItr14108) has been substituted for chromosome 1A. After examining chromosome pairing at metaphase I of meiosis to select double-monosomic (130 1 1A9 1 1D9) F1 plants, the selected plants were crossed to ‘Renville’ (PI510696). An SDS-PAGE F2 progeny test of each F1 plant was conducted as described by Klindworth et al. (2005). This test revealed that some F1 plants had the Glu-D1a glutenin subunits 1Dx2 and 1Dy12 from Langdon 1D(1A). Only those crosses carrying subunits 5110 (Glu-D1d) were advanced to a final round of crossing with Renville. The final cross had the pedigree Langdon 1D(1A)/Len//Langdon/3/2*Renville. The double-monosomic F1 plants were selfed. In the F2, plants with 140 were selected and testcrossed to Langdon doubleditelosomic 1A to identify plants carrying a 1A.1D translocation. In the testcrosses, metaphase I chromosome pairing configurations of 130 1 t10 1 t9 indicated that a spontaneous homoeologous translocation had occurred in the doublemonosomic BC1F1 plant. The final selections of L092 and L252 were from F4 plants, and S99B33 and S99B34 were derived from F5 plants. The translocated segment in all four geneotypes should be identical since all trace back to the same BC1F2 plant, and hence the same translocation event in the BC1F1. The size of the translocated 1DL segments in S99B34 and L252 were characterized by fluorescent genomic in situ hybridization as comprising 31% of the distal end of the translocated arm (Xu et al., 2005). The translocation breakpoint in S99B34 and L252 were also mapped by Xu et al. (2005) to an interval of less than 7.0 cM between microsatellite markers Xgwm135 and Xgwm357 (Röder et al., 1998). In agronomic trials (five location–years) conducted in North Dakota from 2000 to 2002, grain yields of Renville, S99B34, S99B33, L092, and L252 were 256.3, 228.0, 221.1, 196.0, and 188.8 gm, respectively.Heading dates of S99B33 and S99B34 did not differ significantly from Renville (190.6 d), but L092 and L252 headed 2 d later than Renville. Grain volume weights of S99B33, S99B34, Renville, L252, and L092were 728.7, 727.4, 710.7, 709.3, and 695.9 kg m, respectively. The translocation lines had thousand kernel weights of 31.7, 30.3, 30.2, and 30.2 g for S99B33, L092, S99B34 and L252, respectively, which was significantly lower than the 33.8 g of Renville. The lodging score (0–9 scale where 9 indicated severe lodging) was significantly higher for L092 than for Renville (3.9 vs. 3.1, respectively), indicating that L092 had weaker straw than Renville. L252 had significantly lower tillering than Renville, averaging 57.8 vs. 68.6 culms m, respectively. L252 and S99B34 did not significantly differ from Renville (97 cm) in plant height; and while significantly different, S99B33 and L092, were only 4 cm taller than Renville. All four translocation lines have HMW glutenin subunits 1Bx6 and 1By8 conditioned by the Glu-B1d allele. L092, S99B33, and S99B34 have identical low molecular weight (LMW) glutenin subunits and gliadins, also present in Renville (Xu et al., 2005). The LMW subunits, named LMW-2, in these three lines confer stronggluten characteristics todurum wheat (Pogna et al., 1988). However, L252 has the LMW-1 glutenin subunits found in Langdon that are associated with weak gluten, and has gliadins derived from both Langdon and Renville. Quality trials of four location–years from 2000 to 2002 included farinograph and baking tests. Dough mixing characteristics of these translocation lines were inconsistent over years; with dough stability (time interval in minutes for a mixing dough to arrive and depart from the 500 BU line of the farinogram) being either superior or inferior to that of Renville in different years (Klindworth et al., 2005). However, L252 had amean stability of 11.1min versus 8.2min for Renville, andwas consistently longer than that of any other translocation line. Loaf volumes of the translocation lines have been superior to weak-gluten cultivars, but were still below that of Renville. Mean loaf volumes were 497, 469, 438, 433, and 430 cm for Renville, L252, S99B33, L092, and S99B34, respectively. Although the results of Klindworth et al. (2005) indicate that the translocation lines have inconsistent dough mixing characteristics and no improvement in loaf volume, the results also suggest that it may be possible to improve baking quality by combining 5110 with other HMW or LMW glutenin subunits or possibly other gliadins. Therefore, breeders may find these lines useful as parents in crosses combining durum germplasm carrying Glu-D1d with glutenin or gliadins genes from sources that complement Glu-D1d. Seed will be available at the USDA-ARS, Cereal Crops Research Unit, Fargo, ND 58105.