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GENETIC STOCK

Registration of DGE-1, Durum Wheat Alien Disomic Addition Line with Resistance to Fusarium Head Blight

USDA–ARS, Cereals Crops Research Unit, Northern Crop Science Lab., Fargo, ND 58105

^* Corresponding author (prem.jauhar{at}ndsu.edu).

ABSTRACT

The durum wheat (Triticum turgidum L.) alien disomic addition line, DGE-1 (Reg No. GS-156, PI 645483), was developed by the USDA-ARS, Cereal Crops Research Unit, Northern Crop Science Laboratory, Fargo, ND and released in 2006. DGE-1 (2n = 28 + 2) possesses an additional pair of chromosomes from diploid wheatgrass, Lophopyrum elongatum (Host) Á. Löve (2n = 2x = 14; EE genome) conferring resistance to Fusarium head blight (FHB), caused by the fungus Fusarium graminearum Schwabe. The pedigree of DGE-1 is [(Langdon/L. elongatum//Langdon)*1/Langdon]*8. The (Langdon x L. elongatum) F₁ hybrid (2n = 2x = 21; ABE genomes) was backcrossed with the recurrent Langdon parent, then selfed for one generation, and backcrossed again before selfing for several cycles. The addition line with FHB resistance (less than 21% on the visual scale; mean = 6.5% in the generation before release) was obtained by selecting for resistance in each generation after the durum wheat chromosome complement was reconstituted with the added alien chromosome in one and later in double dose. The extra chromosome involved is 1E of L. elongatum.

Abbreviations: EST, Expressed Sequence Tag • FHB, Fusarium head blight • PCR, Polymorphic Chain Reaction • SSR, Simple Sequence Repeat • TRAP, Targeted Region Amplified Polymorphism

The durum wheat (Triticum turgidum L., 2n = 4x = 28; AABB genomes) alien disomic addition line, DGE-1 (Reg. No.GS-156, PI 645483), was developed by the USDA-ARS, Cereal Crops Research Unit, Northern Crop Science Laboratory, Fargo, ND and released in 2006. DGE-1 (2n = 28 + 2) possesses an additional pair of chromosomes from diploid wheatgrass, Lophopyrum elongatum (Host) Á. Löve (2n = 2x = 14; EE genome), that confers resistance to Fusarium head blight (FHB) caused by the fungus Fusarium graminearum Schwabe.

Current cultivars of durum wheat have very little or no resistance to the devastating fungal disease. Some wheatgrasses are highly resistant to FHB, the diploid wheatgrass, L. elongatum being one of the most resistant grasses with only 3.75% Type-2 infection (Jauhar and Peterson, 1998). Since 1987, we in the Durum Germplasm Enhancement (DGE) Project, Fargo, ND, have made several crosses between durum wheat and L. elongatum (Jauhar, 1992a, b; Jauhar and Almouslem, 1998; Jauhar and Peterson, 1996, 2000a). By hybridizing the durum cultivar Langdon with L. elongatum, followed by a series of backcrosses and selfings in the last 10 years, we synthesized the disomic addition, line DGE-1, with 30 chromosomes (2n = 28 + 2). The pedigree of DGE-1 is [(Langdon/L. elongatum//Langdon)*1/Langdon]*8.

Methods

We hybridized the durum cultivar Langdon with L. elongatum (PI 531719), using the methods of emasculation and pollination standardized earlier (Jauhar and Peterson, 1996). The F₁ hybrids were backcrossed to the parental cultivar followed by a series of backcrosses and selfings in the last 10 years, and we synthesized the disomic addition, DGE-1, with 30 chromosomes (2n = 28 + 2). Through this process we produced numerous fertile hybrid derivatives with alien chromatin integrated into the durum genome. These hybrid derivatives were promising from the standpoint of FHB resistance. However, the alien chromatin integration was not stable and was mostly lost in subsequent generations (Jauhar, 2001). We produced several durum monosomic additions (2n = 28 + 1), with the wheatgrass chromosome as a monosome, and derived from them disomic additions with 30 chromosomes (2n = 28 + 2) that pair as 15 bivalents, 14 of durum and 1 of L. elongatum. Among these we selected the disomic addition line, DGE-1 with FHB resistance. The selection for resistance was exercised in each generation after the full durum chromosome complement was reconstituted and the added alien chromosome was in a single and later in double dose.

Various characteristics of DGE-1, namely, plant height and morphology, tillering, and heading time were measured under greenhouse conditions with temperature of 21°C ± 3, 16/8 h light regime, and ambient humidity.

Three isolates of F. graminearum were used for each FHB screening at a concentration of 100,000 spores per mL and scored after two weeks and three weeks following inoculation according to the method described earlier (Jauhar and Peterson, 2001). Screening was done by inoculating two adjoining florets in the middle of the spike with 10 µL inoculum per floret. Three spikes per plant were inoculated. The inoculated plants were then misted with water with automatic sprinklers to maintain high humidity for optimal fusarium infection. Scoring was done two weeks after inoculation according to the method described in Jauhar and Peterson (2000b). Based on individual observations on infection percentage in plants scored, the mean FHB infection was calculated. The parental durum cultivar Langdon was used as the control. Spikes on the control plants were inoculated in the same way.

Only plants of DGE-1 scoring 33% or less infection in the spike were selected and advanced to the next generation for further screening. This process was continued until a disomic addition with an infection of 33% or less was obtained.

Characteristics

The disomic addition line is meiotically and hence reproductively stable, forming 15 bivalents (14 of durum and one of L. elongatum) at meiotic metaphase I. The bivalents generally have two chiasmata each. However, in about 5% of the cases, 29-chromosome or even 28-chromosome progeny may be obtained. Such revertants are distinct from the parental disomic addition lines; they are taller than the addition lines and more like the cultivar Langdon in height, color, and other characteristics. DGE-1 readily crosses with other durum cultivars both as male and female parent. Therefore, the alien chromosome is likely to be transmitted to other cultivars following crosses with DGE-1.

Under greenhouse conditions, the disomic addition line showed overall less than 21% infection based on the visual scale to estimate severity of FHB, compared to 80% infection of the Langdon parent. We screened 10 plants (three spikes each) for four generations following the stabilization of chromosome number at the disomic addition level (2n = 28 + 2). The infection range was 7.0 to 12.5% (mean = 9.3%) in the first generation and 3.7 to 14.3% (mean = 6.5%) in the generation before release.

DGE-1 has a plant type somewhat different from the Langdon parent, the plant height being 76.5 cm. The measurements were taken in the greenhouse over eight replicates since the derivation of the disomic addition. DGE-1 has a narrow leaf; small spike with medium length awns, light green to yellow green color; normal tillering, and is one to two weeks later maturing than Langdon. Under greenhouse conditions this genetic stock has 70 to 75% fertility. Seed size of the disomic addition line (100-kernel weight = 2.5 g) is smaller than that of the Langdon parent (100-kernel weight = 3.2 g). The disomic addition has shown 100% seed germination.

Studies using molecular markers (TRAP and EST-derived SSRs) (Li et al., 2006) helped characterize the chromosome involved in the disomic addition showing FHB resistance. PCR using L. elongatum chromosome-specific markers (Mullan et al., 2005) has shown that the added chromosome is 1E of L. elongatum. The disomic addition will be useful for basic and applied research on FHB, but is not meant for direct use by farmers. It should be particularly useful to geneticists, cytogeneticists, breeders, and other researchers engaged in wheat germplasm enhancement.

Availability

Requests for seed should be addressed to the authors at the USDA-ARS, Cereal Crops Research Unit, Northern Crop Science Laboratory, Fargo, ND 58105–5677, USA. Approximately 25 seeds will be supplied on request, and the user would be expected to acknowledge the source.

Footnotes

All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.

Received for publication January 25, 2007.

References

• Jauhar, P.P. 1992a. Synthesis and cytological characterization of trigeneric hybrids involving durum wheat, Thinopyrum bessarabicum, and Lophopyrum elongatum. Theor. Appl. Genet. 84:511–519.
• Jauhar, P.P. 1992b. Intergeneric hybrids between wheat and Lophopyrum: Breeding implications. Proc. 11th International Chromosome Conference, Edinburgh, Scotland, August 1992. (Abstract).
• Jauhar, P.P. 2001. Problems encountered in transferring scab resistance from wild relatives into durum wheat. p. 188–191. In Proc. of the 2001 National Fusarium Head Blight Forum, 8–10 Dec. 2001, Cincinnati, OH.
• Jauhar, P.P., and A.B. Almouslem. 1998. Production and meiotic analyses of intergeneric hybrids between durum wheat and Thinopyrum species. p. 119–126. In A.A. Jaradat (ed.) Proc. Third International Triticeae Symp. Scientific Publ., Enfield, NH.
• Jauhar, P.P., and T.S. Peterson. 1996. Thinopyrum and Lophopyrum as sources of genes for wheat improvement. Cereal Res. Commun. 24:15–21.
• Jauhar, P.P., and T.S. Peterson. 1998. Wild relatives of wheat as sources of Fusarium head blight resistance. p. 179–181. In Proc. of the 1998 National Fusarium Head Blight Forum, Michigan State University, East Lansing, MI.
• Jauhar, P.P., and T.S. Peterson. 2000a. Toward transferring scab resistance from a diploid wild grass, Lophopyrum elongatum, into durum wheat. p. 201–204. In Proc. of the 2000 National Fusarium Head Blight Forum, December 2000, Cincinnati, OH.
• Jauhar, P.P., and T.S. Peterson. 2000b. Progress in producing scab-resistant germplasm of durum wheat. p. 77–81. In Proc. International Symposium on Wheat Improvement for Scab Resistance, Nanjing Agricultural University, Nanjing, China.
• Jauhar, P.P., and T.S. Peterson. 2001. Hybrids between durum wheat and Thinopyrum junceiforme: Prospects for breeding for scab resistance. Euphytica 118:127–136.[CrossRef]
• Li, J., D.L. Klindworth, F. Shireen, X. Cai, J. Hu, and S.S. Xu. 2006. Molecular characterization and chromosome-specific TRAP-marker development for Langdon durum D-genome disomic substitution lines. Genome 49:1545–1554.[Medline]
• Mullan, D.J., A. Platteter, N.L. Teakle, R. Appels, T.D. Colmer, J.M. Anderson, and M.G. Francki. 2005. ESR-Derived SSR markers from defined regions of the wheat genome to identify Lophopyrum elongatum-specific loci. Genome 28:811–822.

This Article Abstract Full Text (PDF) Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Jauhar, P. P. Articles by Peterson, T. S. Search for Related Content PubMed Articles by Jauhar, P. P. Articles by Peterson, T. S. Agricola Articles by Jauhar, P. P. Articles by Peterson, T. S.