Registration of two germplasms of common wheat with interstitial translocations of Triticum speltoides carrying leaf rust and greenbug resistance genes

 A. J. Lukaszewski 1, D.R. Porter2 , E. F. Antonelli3, and J. Dubcovsky 4

Crop Science. 2000. 40:590

1 Department of Botany and Plant Sciences, University of California, Riverside, CA 92521-0124, USA.

2 USDA-ARS, 1301 N. Western Rd., Stillwater, OK, 74075-2714, USA

3 Instituto de Genética, INTA, Villa Udaondo, 1712 Castelar, Buenos Aries, Argentina.

4 Department of Agronomy and Range Science, University of California, Davis, CA 95616-8515, USA.

 

Abbreviations: Gb,  Greenbug resistance gene, Lr, Leaf rust resistance gene, Ph1: gene controlling homeologous pairing.

 Two interstitial translocations were developed to transfer leaf rust and greenbug resistance genes from chromosome 7S#1 of Triticum speltoides (Tausch) Gren. to hexaploid wheat. Chromosome 7S#1 was found  in a population of bread wheat resulting from irradiation of seed of a hybrid CI15092 / T. speltoides // ’Fletcher’ / 3 / 5*’Centruk’ with fast neutrons (Wells et al. 1982). Interstitial segments of chromosome 7S#1 were transferred to chromosome 7A of hexaploid wheat (Triticum aestivum L.) using homeologous recombination induced by the ph1b mutation (Lukaszewski, A. 1995). Sears’ (1981) strategy was followed to reduce the length of the alien chromosome segments. All manipulations were performed in hard white spring cultivar  ‘Pavon’; three backcrosses were made after the induction of homoeologous recombination and plants homozygous for the interstitial translocations were selected by C-banding.  Translocations were characterized using molecular markers (Dubcovsky et al. 1998).

The short arm translocation line T7AS-7S#1S-7AS·7AL carries resistance gene Lr47 for leaf rust (Puccinia recondita Rob. ex Desm.). This gene confers resistance to a wide spectrum of leaf rust races including nine that are virulent on resistance genes Lr1 and Lr10 present in cv. Pavon (PRT codes: TBT, NBB, MBR, LCG, SDJ, MBG, NDB, MCG, and TDD; Long and Kolmer 1989). The T. speltoides segment present in this translocation is located 2 to 10 cM from the centromere and is 20 to 30 cM long (Dubcovsky et al. 1998).

The long arm translocation line T7AS·7AL-7S#1L-7AL carries gene Gb5  (Tyler et al. 1987) that confers resistance to greenbug (Schizaphis graminum Rondani) biotypes C, E, I, and K but not to biotypes B, F, G, H. This gene is located on an interstitial T. speltoides chromosome segment that is 40 to 50 cM long and is located 18 to 22 cM from the centromere of chromosome 7AL (Dubcovsky et al. 1998).

          The interstitial segments of T. speltoides chromosome present in both translocation lines do not recombine with wheat chromosome 7A in the presence of the wild-type Ph1 locus and will be transmitted as single loci. Consequently, Lr47 is completely linked to RFLP markers Xwg834, Xcdo475, Xmwg710, Xabc152, Xabc158, XBrz, and Xabc465, and Gb5 is completely linked to RFLP markers Xpsr129, Xpsr547, Xwg380, Xabg461, Xwg420, Xmwg2062, and Xpsr680. Molecular markers can be also used to transfer leaf rust resistance gene Lr10 present in chromosome 1A of the recurrent variety Pavon (Schachermayer et al. 1997).

Though these translocation lines may be useful in breeding, no information is currently available on putative yield penalties associated with other genes present in the interstitial segments of T. speltoides chromosome 7S#1. Seed samples of these translocation lines have been deposited in the USDA-ARS National Small Grain Collection P.O. Box307, Aberdeen, ID 83210. Small quantities can be obtained for research and breeding purposes from the curator of the National Small Grain Collection or from the senior author.

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Dubcovsky J., A. J. Lukaszewski, M. Echaide, E. F. Antonelli, and D.R. Porter 1998. Molecular characterization of two Triticum speltoides interstitial translocations carrying leaf rust and greenbug resistance genes. Crop Sci. In press.

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Sears, E.R. 1981. Transfer of alien genetic material to wheat. Wheat Science - Today and Tomorrow. Cambridge, Cambridge University Press. 75-89.

Schachermayr, G., C. Feuillet, and B. Keller. 1997. Molecular markers for the detection of the wheat leaf rust resistance geneLr10 in diverse genetic backgrounds. Molecular Breeding 3: 65-74.

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