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a Dep. of Plant Sciences, North Dakota State Univ., NDSU Dep. 7670, P.O. Box 6050, Fargo, ND 58108
b International Maize and Wheat Improvement Center (CIMMYT), Apdo Postal 6-641, 06600, Mexico D.F., Mexico
c Mayville University, ND, 58257
d Dep. of Plant Pathology, North Dakota State Univ., NDSU Dep. 7660, P. O. Box 6050, Fargo, ND 58108
* Corresponding author (Mohamed.Mergoum{at}ndsu.edu).
ABSTRACT
Steele-ND/ND 735 (Reg. No. MP-1, NSL 462030), a hard red spring wheat (Triticum aestivum L.) (HRSW) recombinant inbred lines (RILs) population, was developed and released by the North Dakota State University (NDSU), Fargo, ND, in 2008. This mapping population is composed of 129 F2:9 RILs. The Steele-ND/ND 735 RILs population has been used extensively to study the genetics of resistance to tan spot [caused by Pyrenophora tritici-repentis (Died.) Drechs.], Stagonospora nodorum blotch [caused by Phaeosphaeria nodorum (E. Müller) Hedjarroud], Septoria tritici blotch [caused by Mycosphaerella graminicola (Fückl) J. Schröt. in Cohn], and Fusarium head blight (caused by Fusarium graminearum Schwabe) and to map the resistance genes and quantitative trait loci underlying the above traits. The genetic marker data encompass hundreds of polymorphic Diversity Array Technology (DArT) and simple sequence repeats markers that were collected at Diversity Arrays Technology, Yarralumla, Australia, and NDSU, respectively.
Abbreviations: DArT, Diversity Array Technology • FHB, Fusarium head blight • HRSW, hard red spring wheat • QTL, quantitative trait locus (loci) • RIL, recombinant inbred line • SSR, simple sequence repeats
Steele-ND/ND 735 (Reg. No. MP-1, NSL 462030) is a hard red spring wheat (Triticum aestivum L.) (HRSW) recombinant inbred lines (RILs) population developed and released by the North Dakota State University (NDSU), Fargo, ND, in 2008. This mapping population is composed of 129 F2:9 RILs. The line ND 735 was registered as PI 639729 by Mergoum et al. (2006), and ‘Steele-ND’ was registered as PI 634981 by Mergoum et al. (2005). The Steele-ND/ND 735 RILs population has been used extensively to study the genetics of resistance to tan spot [caused by Pyrenophora tritici-repentis (Died.) Drechs.], Stagonospora nodorum blotch [caused by Phaeosphaeria nodorum (E. Müller) Hedjarroud], Septoria tritici blotch [caused by Mycosphaerella graminicola (Fückl) J. Schröt. in Cohn], and Fusarium head blight (caused by Fusarium graminearum Schwabe) and to map the resistance genes and quantitative trait loci (QTL) underlying the above traits. The genetic marker data encompass hundreds of polymorphic Diversity Array Technology (DArT) (Triticarte Pty. Ltd., Canberra, Australia) and simple sequence repeats (SSR) markers that were collected at Diversity Arrays Technology, Yarralumla, Australia, and NDSU, respectively.
Parents
The line ND 735 was derived from the cross ND 2709/3/‘Grandin’ (PI 531005)*3//‘Ramsey’ (CItr 13246)/ND 622/ND 2809 made at NDSU (Mergoum et al., 2006). ND 735 is an awned, medium-early–maturing semidwarf hard spring wheat with lax head type. ND 735 is highly resistant to leaf rust (caused by Puccinia triticina Eriks.) and stem rust (caused by P. graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn) pathotypes Pgt-QCCJ, -QTHJ, -QFCQ, -RTQQ, -TPMK, -RHTS, and -HPHJ. ND 735 has moderate resistance to Fusarium head blight (FHB) and includes ‘Sumai 3’ (PI 481542) in its pedigree, which is the likely contributing factor for FHB resistance. The line ND 735 shows resistant reaction to tan spot races 1, 2, 3, and 5 and the toxins Ptr ToxA and Ptr ToxB produced by races 1 and 2, and 5, respectively (Singh et al., 2006). This line is also resistant to the leaf spotting diseases Septoria tritici blotch and Stagonospora nodorum blotch (Mergoum et al., 2007).
The wheat cultivar Steele-ND, released in 2004 (Mergoum et al., 2005), has the pedigree of ‘Parshall’ (PI 613587)/ND706, where the pedigree of Parshall is ‘Keene’//Grandin*2/‘Glupro’ (PI 592759) and that of the NDSU hard red spring line ND 706 is [Grandin/3/IAS20*4/H567.71//‘Amidon’ (PI 527682)/4/Glupro]. Steele-ND is an awned cultivar with middense, inclined, and tapering spikes. The culms are white and the peduncle is slightly recurved. Steele-ND is highly resistant to leaf rust and stem rust pathotypes Pgt-QCCJ, -QTHJ, -RTQQ, -TMLK, -TPMK, and -HPHJ. Steele-ND is moderately resistant to FHB but does not include Sumai 3 in its pedigree; hence, resistance is non–Sumai 3 type. The cultivar Steele-ND is highly susceptible to all virulent races of P. tritici-repentis found in the northern Great Plains of North America and the two toxins Ptr ToxA and Ptr ToxB (Singh et al., 2006). Steele-ND is also susceptible to Septoria tritici blotch and Stagonospora nodorum blotch (Mergoum et al., 2007).
Development and Description of the Population
The cross Steele-ND/ND 735 was made in fall 2001 at NDSU using seed of the parents that were developed at the same institute. The F1 generation of the cross resulting in the development of Steele-ND/ND 735 population was planted in the greenhouse in spring 2002, and the F2 population was grown in the field at the Prosper, ND, experiment station in summer 2002. About 250 F2 plants were randomly selected and inbred to the F8 generation by single-seed descent. Subsequently, headrow lines were planted to get F2:9 RILs in the field at the Prosper, ND, experiment station in the summer of 2007. Rapid advance of the segregating generations were done by growing under greenhouse and field conditions at NDSU, Fargo. Presently this population is made up of 129 F2:10 RILs. These RILs were used for evaluation of morphological and agronomic traits, disease resistance, and construction of genetic map and QTL discovery from 2007 to 2008.
In 2007 and 2008, the Steele-ND/ND 735 RILs population, the parents, and most popular cultivars in the region were grown in replicated yield trials at three locations across North Dakota. These locations are Casselton, Prosper, and Carrington, ND. Based on these trials conducted at six location-years in North Dakota, the parents differed significantly for many agronomic traits. It was also observed that the Steele-ND/ND 735 RILs population segregated for several agronomic traits. The number of days to heading varied from 60 to 64 d for the earliest and latest RILs, respectively, while ND 735 and Steele-ND headed 62 and 60 d after planting, respectively (Table 1 ). Similarly, plant height of the RILs varied from 77.9 to 104.2 cm for the shortest and tallest RILs, respectively, a 26.3-cm spread for this trait. However, the plant height of Steele-ND (90.5 cm) and ND 735 (97 cm) did not show such large difference. Based on the same trials, grain yield of Steele-ND (4930 kg ha–1) was slightly higher than ND 735 yield (4862 kg ha–1) but significantly different (P < 0.05). However, the population RILs showed substantial and significant differences (P < 0.05) in grain yield and varied from 2729 to 5997 kg ha–1 for the lowest- and highest-yielding RILs, respectively. Finally, the grain volume weight varied from 725 and 808 kg m–3 among the RILs, while ND 375 and Steele-ND had 785 and 775 kg m–3 volume weights, respectively (Table 1).
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Genetic Map of the Population
The high-throughput genome analysis method called Diversity Arrays Technology (DArT) (Akbari et al., 2006) has been used in this population to develop the genetic map. The DArT technology generates whole-genome fingerprints by scoring the presence versus absence of thousands unique DNA fragments in a genomic sample by using the nature of the microarray platform (Jaccoud et al., 2001). Out of 129 RILs of this population, 118 RILs were used in developing the genetic map. Altogether 2300 DArT markers were screened of which 429 were found to be polymorphic. The genetic map generated by these 429 markers on 118 RILs was distributed across the entire wheat genome as there were 42 linkage groups each accounting for a chromosome arm. The average distance between the markers was about 5 cM, and there were 2 to 36 markers in each linkage group. To map the potential genes for toxins Ptr ToxA and Ptr ToxB, 20 microsatellite markers; gwm (Röder et al., 1998), barc (Song et al., 2005), and wmc (Somers et al., 2004) previously mapped to chromosome 2B and 5B were used to screen the parental lines for polymorphisms. As the DArT markers had shown the region for the markers associated to Ptr ToxA and Ptr ToxB resistance, we just needed a few SSR markers to make the map rich in those regions. Ten of those markers found to be polymorphic on the parents were run on the entire RILs population. The genetic map generated by these 429 markers and the 10 SSR markers helped us to find closer markers for the resistance genes and have a better comparison with the other SSR genetic maps that are more common.
Molecular analysis reveal the location of the resistance genes effective against tan spot caused by spore suspension and culture filtrate of P. tritici-repentis races 2 and 5 to be on long arm of chromosome 5B (Tsr1) and short arm of chromosome 2B (Tsr6), respectively. It was also observed that the gene controlling resistance to Stagonospora nodorum blotch caused by P. nodorum isolate Sn2000 and its culture filtrate was located on long arm of chromosome 5B (Tsn1) (Fig. 2 ). The same recessive gene controls resistance to tan spot caused by P. tritici-repentis races 2 and Stagonospora nodorum blotch caused by P. nodorum isolate Sn2000 in the Steele-ND/ND 735 population.
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Availability
Seed of Steele-ND/ND 735 RILs mapping population and its parents Steele-ND and ND 735 will be maintained by the Spring Wheat Breeding Program, Agricultural Experiment Station, North Dakota State Univ., Fargo ND 58108-6050. Multiplication and distribution rights of certified seed classes of Steele-ND have been transferred from NDSU to the NDSU Research Foundation, 1735 NDSU Research Park Drive, Fargo, ND 58108. Steele-ND is protected under the U.S. Plant Variety Protection Act with recognized classes of Foundation, Registered, and Certified seed (PVP no. 200400188). Upon request to the corresponding author, a small quantity of seeds of the Steele-ND/ND 735 RILs and the parents can be obtained for research purposes and for use in transferring agronomic, quality traits, and foliar diseases and FHB resistance to cultivars. Appropriate recognition of the source should be noted if the population contributes to research on tan spot, rusts, and FHB or to the development of new genetic stocks, molecular tools, germplasm, or cultivars.
Acknowledgments
Financial support from 2005 to 2008 from Wheat Research and Promotion Council, Minnesota, North Dakota Wheat Commission, North Dakota, State Board of Agricultural Research and Education, North Dakota, USA, and U.S. Wheat and Barley Scab Initiative, USA, is gratefully acknowledged. Additionally the molecular component of this project was supported in part by the National Research Initiative of USDA's Cooperative State Research, Education and Extension Service, CAP grant number 2006-55606-16629.
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 April 14, 2009.
References
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