Journal of the Science of Food and Agriculture J Sci Food Agric 85:2445–2452 (2005) DOI: 10.1002/jsfa.2272 Relationship between glutenin subunit composition and gluten strength measurements in durum wheat † Mike J Sissons, 1∗ Nancy P Ames, 2 Ray A Hare 1 and John M Clarke 3 1 NSW Agriculture, Tamworth Agricultural Institute, Tamworth, RMB 944, NSW 2340 Australia 2 Agriculture and Agri-Food Canada, Cereal Research Centre, Winnipeg, MB, Canada R3T 2M9 3 Agriculture and Agri-Food Canada, Semi-Arid Prairie Research Centre, Swift Current, SK, Canada S9H 3X2 Abstract: Durum breeders use a range of techniques in the development of new cultivars. An important selection criterion is the rheological properties of semolina dough and durum wheat breeders use this criterion in the development of new cultivars using a range of techniques. Because of the need to process large numbers of genotypes encountered in breeding programs, methods that are inexpensive, rapid, require small amounts of sample and that correlate with semolina quality are desirable. Using breeding material, this study investigated the relationship between the glutenin subunit composition and two traditional tests of gluten strength, gluten index (GI) and mixograph. Two sample sets of durum wheat breeding lines and cultivars, one grown in Canada (n = 229) and the other grown in Australia (n = 139) were analysed for GI, mixograph and both high molecular weight (HMW) and low molecular weight (LMW) glutenin subunits by SDS-PAGE. Nine different HMW and 14 different LMW allelic combinations were found. In the Canadian set, the most frequent LMW alleles were aaa, bba, caa and cfa while in the Australian set, caa was predominant. For the HMW subunits, the most common allelic groups were Glu-A1c/Glu-B1d (null, 6 + 8) and Glu-A1c/Glu-B1b (null, 7 + 8) with fewer numbers of Glu-A1c/Glu- B1e (null, 20) in both sample sets. LMW subunits were more important contributors to gluten strength than HMW subunits with the rank for higher GI according to the LMW allele (Canadian set) being caa = aaa > bba and aaa > cfa while HMW subunits 6 + 8 = 7 + 8 > 20. Similarly, using the mixograph, strength ranking for the LMW alleles was aaa > cfa = bba and HMW subunit 20 gave poorer rheological properties. For some samples with a good LMW allelic group a low GI was observed and vice versa. Further characterisation of the protein composition in these samples showed the GI results could be explained by polymeric/monomeric (P/M), glutenin/gliadin (Glu/Gli) and HMW/LMW ratios or the proportion of unextractable polymeric protein.  Crown in the right of the State of New South Wales, Australia; and for the Department of Agriculture and Agri-Food, Government of Canada,  Minister of Public Works and Government Services Canada 2005. Published for SCI by John Wiley & Sons, Ltd. Keywords: durum wheat; gluten index; mixograph; low molecular weight glutenin subunits; high molecular weight glutenin subunits; breeding INTRODUCTION The endosperm storage protein composition and quantity in durum wheat has a major impact on dough rheological properties and pasta cooking quality. Gliadins and glutenins are the main storage proteins in wheat. Glutenins consist of high molecular weight (HMW) and low molecular weight (LMW) subunits coded by Glu-1 and Glu-3 loci, respectively. It is generally thought that pasta made from strong gluten wheat has greater cooked firmness and cooking stability, whereas pasta made with weak gluten is prone to deteriorate rapidly and become soft with overcooking. 1 Knowledge of the composition of gluten components associated with superior end-product quality can be used by plant breeders to select parental lines that will produce progeny with the preferred genetic combinations and enable selection in early generations. γ -Gliadin 45 and 42 are useful markers for good and poor quality gluten strength 2 and this is due to the genetic linkage with low molecular weight glutenin subunits 3 . Carrillo et al 4 showed that there are different LMW-1 and LMW-2 types: LMW 1, 1 − , 2, 2 − , and 2* with the LMW-2 and LMW- 2 − showing higher gluten strength but with overlap in the range of strength measurements for the three ∗ Correspondence to: Mike J Sissons, NSW Agriculture, Tamworth Agricultural Institute, Tamworth, RMB 944, NSW 2340, Australia E-mail: mike.sissons@agric.nsw.gov.au † Presented in part at the AACC Annual Meeting 2003 (Received 15 February 2004; revised version received 21 October 2004; accepted 16 March 2005) Published online 17 August 2005  Crown in the right of the State of New South Wales, Australia; and for the Department of Agriculture and Agri-Food, Government of Canada,  Minister of Public Works and Government Services Canada 2005. Published for SCI by John Wiley & Sons, Ltd. 2445