1 Arabinoxylan content of hard winter and spring wheats of the U.S. Pacific Northwest

The development of high quality wheat (Triticum aestivum L.) cultivars depends on a thorough understanding of the genetic and environmental influences on the constituents of grain. Arabinoxylans are important albeit quantitatively minor constituents of wheat grain; they can interact with large weight ratios of water and participate in oxidative cross-linking and gel formation. In this study, 25 hard winter and 25 hard spring wheat genotypes from breeding programs in the U.S. Pacific Northwest were analyzed for water-soluble and total arabinoxylan contents. Each genotype set was grown in three environments. There were significant differences among water-extractable (WE-AX) and total (TO-AX) arabinoxylan contents (G, E, and G*E model R2s 0.64-0.96). WE-AX genotype mean content ranged about 2-fold, from 0.39 to 0.81 % for winter, and 0.48 to 0.92 % for spring wheat genotypes. TO-AX genotype mean content ranged from 3.1 to 4.0 % for winter and 3.9 to 4.7 % for spring genotypes. Type III Sums of Squares F-ratios for ‘genotype ’ were highly significant (P<0.0001) for both AX fractions of both winter and spring genotypes. ‘Hollis ’ spring wheat had the highest WE-AX content and ‘WQL9HALP ’ spring wheat (a hard NIL to ‘Alpowa’) had the highest TO-AX content. Repeatability estimates were 0.71 and 0.89 for WE-AX, winter and spring; and 0.30 and 0.62 for TO-AX, winter and spring genotypes, respectively. These preliminary results indicate that there is sufficient repeatable genetic variation to improve hard winter and spring wheat cultivars for AX contents