Characterization Of High And Low Molecular Weight Glutenin Subunits By Molecular Markers And Their Effect On Processing Quality In Wheat

Improvement of dough properties is an important target for Chinese wheat quality breeding program.The composition and quantity of high and low molecular weight glutenin subunits (HMW-GS andLMW-GS) play an important role in determining dough properties and end-use quality of wheatproducts. In the present study,718wheat cultivars and advanced lines from20countries werecharacterized for the HMW-GS and LMW-GS with allele-specific molecular markers, and thenear-isogenic line of Aroona was used to understand the effect of the composition and quantity ofglutenin subunits on the processing quality.1. The allele-specific molecular markers Ax2~*, Bx7OE, By8, By9, By16, Dx5, Glu-A3and Glu-B3were used to characterize718wheat cultivars and advanced lines from20countries. For the Glu-A1locus,311cultivars (43.3%) had the allele Ax2~*, which predominated in cultivars from Canada (83.3%),Romania (91.7%), Russia (72.2%) and USA (72.2%). At Glu-B1locus,197cultivars (27.4%) containedthe By8subunit and its frequency was higher in Japanese (60.0%) and Romanian (62.5%) genotypesthan in those from other countries;264cultivars (36.8%) carried the By9subunit, mostly existing in thecultivars from Austria (100.0%), Russia (72.2%), and Serbia (72.7%); the By16subunit was present in44cultivars (6.1%), with a relatively high percentage in Chile (19.5%) and Japan (30.0%); thefrequency of Bx7OEwas3.1%, and was found only in cultivars from Argentina (12.1%), Australia(4.1%), Canada (25.0%), Iran (20.0%), and Japan (30.0%). There were446genotypes (62.1%) with thesubunit Dx5at the Glu-D1locus, high frequencys of Dx5occurred in cultivars from Hungary (90.0%),Romania (95.8%), and Ukraine (92.3%). At the Glu-A3locus,49(6.8%) and92(12.8%) cultivarscarried Glu-A3b and Glu-A3d, high frequencys were found in cultivars from Australia (39.7%) andFrance (24.5%), respectively; At the Glu-B3locus,160(22.3%),20(2.8%) and195(27.2%) cultivarspossessed the superior subunits Glu-B3b, Glu-B3d, and Glu-B3g, respectively, high frequencies werefound in the cultivars from Romania (62.5%), Mexico (14.3%) and Norway (77.3%), respectively. Thefrequency of the1B/1R translocation was13.4%and it occurred in cultivars from all countries exceptAustralia, Austria, Norway, and Serbia. The functional markers applied in this study, in agreement withthe results of SDS-PAGE, were accurate and can be widely used in marker assistant selection in wheatquality breeding.2. Aroona and its near-isogenic lines (NILs) with different HMW-GS and LMW-GS were used toinvestigate the relationship between the composition and quantity of glutenin subunits and theprocessing quality.(1) For dough strength, different gltenin subunit loci was ranked as Glu-D1＞Glu-B3＞Glu-B1＞Glu-A3＞Glu-A1＞Glu-D3and for dough extensibility, Glu-B3＞Glu-A3＞Glu-D3＞Glu-D1＞Glu-B1＞Glu-A1.(2)7+9,17+18,5+10, Glu-A3b, Glu-A3d, Glu-A3f, Glu-B3b, and Glu-B3g were correlated withsuperior dough strength. For dough extensibility, a significant difference was found only at Glu-A3, and Glu-A3e was the most inferior allele. For the quantity of glutein protein fractions,17+18,5+10,Glu-A3b, Glu-A3d, Glu-A3f and Glu-B3g showed significantly higher%UPP.(3) For pan bread quality,7+9had significant better shape,5+10showed better shape, inner colorand higher total score, Glu-A3b exhibited better loaf volume, Glu-A3c showed higher total score,Glu-A3f possessed significantly smoothness and Glu-B3g showed significantly better loaf volume,better structure and higher total score.(4) For fresh white Chinese noodle quality,7~*+8,17+18, and5+10exhibited better whiteness,Glu-B3a and Glu-B3d showed significantly better smoothness and Glu-A3b, Glu-B3g, and Glu-B3h hadbetter whiteness.(5) For Chinese steamed bread quality,1showed significant better shape,7~*+8and6+8~*hadsignificant better stress relaxation,5+10showed significant better external color, Glu-A3e showed betterstress relaxation, Glu-B3a showed better stress relaxation, external color and higher total score, Glu-B3bhad better external color.(6) Genotypes with1,7+9,5+10, Glu-A3c, Glu-B3b, Glu-D3c performed the best dough strength,1,7+9,2+12, Glu-A3c, Glu-B3i, Glu-D3c showed the best dough extensibility,1,7+9,5+10, Glu-A3c,Glu-B3b, Glu-D3c showed the best shape, inner color and taset flavour of pan bread,1,7+9,2+12,Glu-A3c, Glu-B3b, Glu-D3f had the largest loaf volume, best inner color and highest total score of panbread. Genotypes with1,7+9,2+12, Glu-A3c, Glu-B3d, Glu-D3c performed the best viscoelasticity offresh white Chinese noodle, and genotypes with1,7+9,2+12, Glu-A3e, Glu-B3b, Glu-D3c showed thebest stress relaxation and total score of Chinese steamed bread.