Composition and functional analysis of low-molecular-weight glutenin alleles with Aroona near-isogenic lines of bread wheat

Abstract

BackgroundLow-molecular-weight glutenin subunits (LMW-GS) strongly influence the bread-making quality of bread wheat. These proteins are encoded by a multi-gene family located at the Glu-A3, Glu-B3 and Glu-D3 loci on the short arms of homoeologous group 1 chromosomes, and show high allelic variation. To characterize the genetic and protein compositions of LMW-GS alleles, we investigated 16 Aroona near-isogenic lines (NILs) using SDS-PAGE, 2D-PAGE and the LMW-GS gene marker system. Moreover, the composition of glutenin macro-polymers, dough properties and pan bread quality parameters were determined for functional analysis of LMW-GS alleles in the NILs.ResultsUsing the LMW-GS gene marker system, 14–20 LMW-GS genes were identified in individual NILs. At the Glu-A3 locus, two m-type and 2–4 i-type genes were identified and their allelic variants showed high polymorphisms in length and nucleotide sequences. The Glu-A3d allele possessed three active genes, the highest number among Glu-A3 alleles. At the Glu-B3 locus, 2–3 m-type and 1–3 s-type genes were identified from individual NILs. Based on the different compositions of s-type genes, Glu-B3 alleles were divided into two groups, one containing Glu-B3a, B3b, B3f and B3g, and the other comprising Glu-B3c, B3d, B3h and B3i. Eight conserved genes were identified among Glu-D3 alleles, except for Glu-D3f. The protein products of the unique active genes in each NIL were detected using protein electrophoresis. Among Glu-3 alleles, the Glu-A3e genotype without i-type LMW-GS performed worst in almost all quality properties. Glu-B3b, B3g and B3i showed better quality parameters than the other Glu-B3 alleles, whereas the Glu-B3c allele containing s-type genes with low expression levels had an inferior effect on bread-making quality. Due to the conserved genes at Glu-D3 locus, Glu-D3 alleles showed no significant differences in effects on all quality parameters.ConclusionsThis work provided new insights into the composition and function of 18 LMW-GS alleles in bread wheat. The variation of i-type genes mainly contributed to the high diversity of Glu-A3 alleles, and the differences among Glu-B3 alleles were mainly derived from the high polymorphism of s-type genes. Among LMW-GS alleles, Glu-A3e and Glu-B3c represented inferior alleles for bread-making quality, whereas Glu-A3d, Glu-B3b, Glu-B3g and Glu-B3i were correlated with superior bread-making quality. Glu-D3 alleles played minor roles in determining quality variation in bread wheat. Thus, LMW-GS alleles not only affect dough extensibility but greatly contribute to the dough resistance, glutenin macro-polymers and bread quality.

Effect of allelic variation at the Glu-3/Gli-1 loci on breadmaking quality parameters in hexaploid wheat (Triticum aestivum L.)

“…The Glu-A3e allele present in Chu_A3 is a null allele associated with the absence of proteins (Gupta et al, 1989), which may explain the significantly negative effect of the Glu-A3e allele on almost all the quality parameters (ZEL, MPT and MDS). The negative impact of this allele on breadmaking quality parameters was consistent across the three evaluated environments (Table 3) and is also consistent with results from other studies (Branlard et al, 2001;Flaete and Uhlen, 2003;Zhang et al, 2004Zhang et al, , 2012. This negative effect of Glu-A3e is most likely caused by the Glu-A3 deletion, since both Chu_A3 and Tol_A3 carry the same Gli-A1 allele (Gli-A1m) and still showed differences in quality parameters.…”

“…These results suggest that alleles Glu-B3g, Glu-B3b, and Glu-B3i Man confer longer mixing time (~17% longer) than alleles Glu-B3a, Glu-B3i Chu and GluB3h (Table 5) and might be a better target for breeding programs interested in improving gluten strength. A similar ranking for these alleles was proposed by Zhang et al (2012) analyzing Aroona NILs, where quality parameters for lines carrying Glu-B3i, Glu-B3g and Glu-B3b were better than those in lines carrying Glu-B3a and GluB3h alleles. NILs Man_B3 and Chu_B3, which have the same Glu-B3i allele for the STS showed differences for MPT in two of the three individual environments (Table 4).…”

Effects of Allelic Variation in Glutenin Subunits and Gliadins on Baking-Quality in Near-isogenic Lines of Common Wheat cv. Longmai 19

“…The structure of LMW-GS is similar to that of HMW-GS, and the composition of these molecules is also strongly related to wheat baking quality (Payne 1987;Gupta and Shepherd 1990;Sontag-Strohm et al 1996;Redaelli et al 1997;Gianibelli et al 2001). However, the LMW-GS are difficult to distinguish by 1-D SDS-PAGE, mainly because of their overlapping and tight genetic linkage with the gliadins (D'Ovidio and Masci 2004;Zhang et al 2012). Thus, compared with HMW-GS, much less is known about the effects of LMW-GS (Redaelli et al 1995;Gianibelli et al 2001).…”

High-level expression of LMW-GS and α-gliadin genes promoted by the expressed tag sequence of 5′ end in Escherichia coli

“…coli [2,8,10,13,14,32,34,36,42,43]. However, being removed signal sequence, the mRNA of HMW-GS gene Dx failed to be detected by Northern blotting [11].…”

“…The wheat storage proteins consisting of gliadins (including α-, β-, γ-and ω-type) and glutenins (including high and low molecular weight glutenin subunits or respective HMW-GS and LMW-GS) are vital in bread making due to its ability in conferring dough elasticity and extensibility [1][2][3]. Heterologous expression is particularly important for storage protein structure-function studies.…”