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A Novel Pair of HMW Glutenin Subunits from Aegilops searsii Improves Quality of Hexaploid Wheat

¹Laboratory of Plant Genetics and Breeding Science, Faculty of Agriculture, Tottori University, Tottori, 680-8553 Japan. ²National Agricultural Research Center for Western Region, Fukuyama, 721-8514 Japan. ³Corresponding author. Phone: +81-857-315352. Fax: +81-857-315352. E-mail: tsujim@muses.tottori-u.ac.jp

This study involved screening of wild species of wheat in search of functionally useful seed storage proteins for improvement of breadmaking quality of wheat (Triticum aestivum). After screening of 177 disomic addition lines (DALs) of wheat belonging to different wild species, Aegilops searsii DALs were selected and studied in detail. These DALs of Ae. searsii were from chromosome 1S^s to 7S^s in the background of cultivated wheat cv. Chinese Spring (CS). By analyzing these addition lines, genetic loci of actively expressed genes for the high molecular weight glutenin subunits (HMW-GS) and gliadin were found on the chromosome 1S^s for the first time and have been designated as Glu-S^s1 and Gli-S^s1, respectively. Disomic addition line of chromosome 1S^s (DAL1S^s) showed improved dough strength in different generations compared with CS. SDS sedimentation value and specific sedimentation of DAL1S^s were higher than CS. Mixograph peak height and band width were higher, with no difference in mixing peak time from CS. All these factors indicate a positive effect of quantity as well as quality of gluten proteins of Ae. searsii. This was further supported by increased polymer formation in DAL1S^s because the ratio of unextractable polymeric protein to total polymeric protein (UPP/TPP%) of DAL1S^s was significantly higher than CS. Genes for HMW-GS (major determinant of end-product quality in wheat) of Ae. searsii were cloned and sequenced from the DAL1S^s. Phylogenetic analysis of deduced amino acid sequences showed that both x and y HMW-GS were more similar to that of D genome rather than B genome of wheat. Although S genome is structurally more similar to B genome of wheat, functionally it is more similar to the D genome of wheat and possesses good quality HMW-GS required for improvement of breadmaking quality of wheat.