Registration of Three Germplasms of Durum Wheat with Introgressions from Agropyron elongatum and Secale cereale

Three durum wheat (Triticum turgidum var. durum L.) germplasms were developed by cytogenetic chromosome engineering. In two of these (UCRD05–1 [Reg. no. GP-805, PI 639886]; UCRD05–2 [Reg. no. GP-806, PI 639887]), segments of chromosome 7E of Agropyron elongatum (Host) Beauv. [Lophopyrum ponticum (Podp.) Löve] introduce loci Lr19 and Y, for leaf rust [caused by Puccinia recondita Roberge ex Desmaz. f. sp. tritici (Eriks. & E. Henn.) D.M Henderson] resistance and yellow flour pigment, respectively, and in the third germplasm, UCRD05–3 (Reg. no. GP-807, PI 639888), a cytogenetically engineered translocation 1RS.1BL from bread wheat (MA1) replaces chromosome 1B. The pedigrees of two durum wheat germplasms with translocations 1–22 and 1–23 from chromosome 7E of A. elongatum, UCRD05–1, and UCRD05–2, respectively, are: Chinese Spring Ag#1/*4 Pavon 76/*2 Pavon ph1b/3/Opata/4/*4 Aconchi. Cytogenetic manipulations were performed in bread wheat cv. Pavon 76. The so-called Agropyron Transfer 1 produced by E.R. Sears (1977) was transferred from cv. Chinese Spring to Pavon 76 by backcrosses, with four completed. Two subsequent backcrosses were to Pavon ph1b (Lukaszewski, 2000). Heterozygotes for Transfer 1 and homozygotes for ph1b were selected, grown and self pollinated. The resulting progenywere screened by genomic in situ hybridization (GISH) according to Masoudi–Nejad et al. (2002) with probes made of either wheat or A. elongatum total genomic DNA, and block made of the total genomic DNA of the other parent, and recombinant chromosomes were selected. While Transfer 1 involves wheat chromosome 7D, chromosome size and morphology indicated that some recombinants recovered involved wheat chromosomes other than 7D. Sequential C-banding–GISH confirmed that several transfers were located on chromosome 7A. Two such recombinant chromosomes 7AS.7AL-7EL, labeled 1–22 and 1–23, both with short terminal Agropyron segments present on 7AL, were chosen for a transfer to durum wheat. The presence of Lr19 on both segments was confirmed by tests with race BBBQ of leaf rust that is virulent on durum wheat; since it is known that Y is distal to Lr19 (Prins et al., 1996), it was assumed to be present on both recombined chromosomes. The presence of Y was confirmed by an increase in the yellow pigment in grain extracts from plants chromosomes 1–22 and 1–23 (Zhang et al., 2005). The two recombinant chromosomes are similar in structure to the primary recombinants of the same original chromosome 7E produced directly in durum wheat by Ceoloni et al. (2005) that were never publicly released. Bread wheat plants with chromosomes 1–22 and 1–23 were pollinatedwith cv. Opata, and the resulting hybrids were crossed and backcrossed four times to T. turgidum subsp. durum cv. Aconchi. In each generation, plants heterozygotes for 1–22 or 1–23 were identified by GISH. BC4 heterozygous were self pollinated and screened by GISH to identify homozygotes. The effect of the translocations on the agronomic performance of durum wheat is not clear at this point. No reduction in fertility was observed, all translocation lines are resistant to all leaf rust isolates tested, and a significant increase in the yellow pigment content in seed extracts was noted (Zhang et al., 2005). In bread wheat, segments of the long arm of the same chromosome 7E are known to substantially increase yield (Monneveux et al., 2003). The third germplasm of durum wheat, UCRD01–3, also known as Aconchi MA1, received a wheat–rye translocation from bread wheat. The development of translocation MA1 in bread wheat was described by Lukaszewski (2000). The pedigree of this durum germplasm is: Genaro 81/7*Pavon 76//Pavon ph1b/3/4*Pavon 76/4/Opata/5/4*Aconchi. ChromosomeMA1 is a centric translocation 1RS.1BL from cv. Kavkaz cytogenetically engineered by homoeologous recombination to remove locus Sec-1 that encodes rye secalin and to introduce loci Gli-B1 and Glu-B3 encoding gliadins and low molecular glutenins, respectively (Lukaszewski, 2000). Chromosome MA1 is a five-breakpoint translocation. This includes four breakpoints flanking the two wheat inserts on 1RS and the breakpoint in the centromere. To transfer chromosomeMA1 to durum wheat, PavonMA1 was crossed to cv. Opata and the resulting F1 hybrids were crossed and backcrossed four times to cv. Aconchi. In each generation, selection for translocation heterozygotes and against disassembled chromosomes MA1 was by C-banding. Following BC4, translocation heterozygotes were self pollinated and their progenies screened by C-banding to isolate translocation homozygotes. The transmission rates of MA1 in backcrosses did not deviate from normal (50%) and the segregation ratio in BC4F2was about 1:2:1. Yet, it appeared that seed set of translocation homozygotes was reduced relative to cv. Aconchi. Other agronomic or quality effects of the translocation MA1 in durum wheat are not known at this time. Small quantities of seed (1–2 g) of these three translocation lines of durum wheat can be obtained for research and breeding purposes from the author with a standard Material Transfer Agreement.