Cytological and Molecular Characterization of Homoeologous Group-1 Chromosomes in Hybrid Derivatives of a Durum Disomic Alien Addition Line

Abstract

Earlier, we produced a stable Fusarium head blight (FHB)-tolerant durum wheat (Triticum turgidum L.) alien disomic addition line, DGE-1 (released in 2008), incorporating chromosome 1E of diploid wheatgrass [Lophopyrum elongatum (Host) A. Love; 2n = 2x = 14; EE]. For stable FHB resistance, the ultimate goal would be to transfer resistance from 1E into the durum chromosome 1A or 1B. Such transfer is more likely to occur when these target chromosomes are in a single dose. Therefore, we crossed DGE-1 with ‘Langdon’ substitution lines 1D(1A) and 1D(1B) and produced hybrid derivatives with chromosomes 1A, 1B, 1D, and 1E in a single dose. As an important fi rst step, we standardized a method to readily identify these group-1 chromosomes. Multicolor fl uorescent genomic in situ hybridization that we standardized earlier is useful for such identifi cation but is tedious and expensive. To identify these chromosomes more expeditiously and economically in a large plant population, we also used chromosome-specifi c molecular markers and identifi ed each of the group-1 chromosomes. We used marker Xwmc333 to identify chromosome 1A, Xwgm18 for 1B, Xwmc147 for 1D, and Xedm17 for 1E. Xedm17, which profi les chromosome 1E, also generated two characteristic bands for chromosome 1D and may therefore be useful in identifying both chromosomes simultaneously. DURUM WHEAT (Triticum turgidum L.; 2n = 4x = 28; AABB) is an important cereal used for human consumption in the United States, Canada, and most European countries, including Italy, Turkey, France, Romania, and Ukraine. On the evolutionary ladder, durum wheat is a forerunner of bread wheat (Triticum aestivum L.; 2n = 6x = 42; AABBDD) and evolved in nature long before the latter (see Jauhar, 2006). Durum wheat is a natural hybrid, having resulted from hybridization between related wild species in conjunction with doubling of chromosome number. Th us, it enjoys the benefi ts of both polyploidy and hybridity. It has a unique cytogenetic architecture and its chromosomes can be divided into seven homoeologous groups of two chromosomes each (Fig. 1). Th e chromosomes within a homoeologous group are genetically and evolutionarily related. Durum wheat can tolerate addition of certain chromosomes, of related species, syntenic to those within a homoeologous group. A related species, diploid wheatgrass [Lophopyrum elongatum (Host) A. Love; 2n = 2x = 14; EE genome] is an excellent source of Fusarium head blight (FHB) resistance (Jauhar and Peterson, 1998). In our earlier work on durum germplasm enhancement (DGE), we produced a stable alien disomic addition line, DGE-1, incorporating chromosome 1E of L. elongatum (Jauhar and Peterson, 2008; Jauhar et al., 2009). DGE-1 is the fi rst alien addition line of its kind with a novel source of FHB resistance from chromosome 1E. Th e ultimate goal would be to transfer FHB resistance from the added alien chromosome 1E into the durum chromosome complement. Homoeologous group-1 chromosomes 1A and/or 1B of durum wheat would naturally be the logical Published in The Plant Genome 4:102–109. Published 21 June 2011. doi: 10.3835/plantgenome2011.01.0002 © Crop Science Society of America 5585 Guilford Rd., Madison, WI 53711 USA An open-access publication 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. USDA-ARS, Northern Crop Science Lab., Fargo, ND 58102. Mention of trade names or commercial products in this publication is solely to provide specifi c information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. Received 26 Aug. 2010. *Corresponding author (prem.