Variation at Glu-1 Loci in Club Wheats

Hexaploid club wheats (Triticum aestivum L.) possess unique end-use quality characteristics and are grouped as a U.S. market subclass of soft white common wheat. Although there have been many reports on associations among high-molecular-weight glutenin storage protein (HMW-Glu) sub-units with end-use quality in hard wheats; there has been very limited work done on surveying the club wheats for these subunits. The HMW-Glu subunits, spike types and grain color were determined for 41 U.S. club wheat cultivars and 79 club accessions obtained from the National Small Grains Collection (NSGC), USDA-ARS. Accession ‘Harlan JR 35’ (PI 420948), which appears morphologically to be a hexaploid club wheat, was determined to be tetraploid. Egyptian line ‘Maya II-Tel's’ (PI 422288) was shown to have previously undescribed HMW-Glu subunits. In the U.S. club wheats the most common HMW-Glu subunits were: null, 49 % (Glu-A1); 6, 37 % (Glu-B1); and 2 + 12, 94 % (Glu-D1). In the NSGC group the most common HMW-Glu sub-units were: 2*, 52 % (Glu-A1); 7 + 8, 31 % (Glu-B1); and 2 + 12, 92 % (Glu-D1). The high frequency of subunits 2 + 12 in the club wheat groups has not been observed previously in numerous surveys of diverse wheat cultivars. The Glu-B1 subunits 6 (without subunit 8) and 20 which have not been reported in US red wheats, were shown to be common in both club wheat groups. A comparison of diversity indices, including previous studies on HMW-Glu subunit frequencies on all market classes of wheat, showed that the club groups are as diverse for the Glu-A1 and Glu-B1 loci and less diverse for the Glu-D1 locus.