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

Abstract

Cereal Chem. 86(1):26-32This 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 s 1 and Gli-S s 1, 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.The unique breadmaking property of bread wheat (Triticum aestivum) lies in its proteins (glutenins and gliadins). Among these two types of proteins, glutenins and especially the high molecular weight glutenin subunits (HMW-GS) have a major effect on breadmaking quality. After initial studies of Payne et al (1979), in which the presence or absence of HMW-GS was related to breadmaking quality, numerous investigations were made to find functionally useful HMW-GS in wheat. However, only a very limited number of these were reported in wheat (e.g., 5+10 vs. 2+12 coded by the Glu-D1 locus). This is because of neutral variation available in the cultivated hexaploid wheat. Screening for good-quality subunits in related wild species of wheat is important for improving the breadmaking quality of wheat. Aegilops searsii (S s S s , 2n = 2x = 14) is a wild species native to the subMediterranean region of Israel, Jordon, southwestern Syria, and southeastern Lebanon (Feldman and Kislev 1977). It belongs to section Sitopsis of the genus Aegilops (Feldman and Kislev 1977;van Slageren 1994). In addition to Ae. searsii, the section Sitopsis contains Ae. bicornis (S b S b , 2n = 2x = 14), Ae. long...

Exploration of Triticeae seed storage proteins for improvement of wheat end-product quality

“…Our studies on Ae. umbellulata addition lines have indicated slight negative effects on dough strength (Garg et al 2009a). Similar negative effects have been found in 1U g addition line of Ae.…”

“…Homoeologous group 1 addition lines of Ae. searsii (Garg et al 2009a) and Ae. longissima (Garg et al 2007b) expressing gliadins and glutenin proteins in the wheat genetic background showed improved dough strength, and thus these lines could be useful resources for improvement of wheat bread-making quality (Fig.…”

Introgression of useful genes from Thinopyrum intermedium to wheat for improvement of bread‐making quality

“…Grain and flour characteristics, rheological studies and size‐exclusion high‐performance liquid chromatography (SE‐HPLC) for unextractable polymeric proteins were carried out as described previously (Garg et al. ). The sodium dodecyl sulphate sedimentation (SDSS) test was performed with 3.5 g of milled flour according to Takata et al.…”

“…Complete HMW‐GS genes were amplified from genomic DNA by PCR (Garg et al. ), cloned and sequenced from both termini. A search for the best match was then performed using the BLAST link of NCBI.…”

Characterization of HMW Glutenin Subunits in Thinopyrum intermedium, Th. bessarabicum, Lophopyrum elongatum, Aegilops markgrafii, and Their Addition Lines in Wheat

“…(See McIntosh et al, 2008). These HMW‐GSs in wild relative species of wheat may be alternative resources for improvement of wheat quality (Feng et al, 2004; Garg et al, 2008, 2009b).…”