Genetic diversity of HMW glutenin subunits in diploid, tetraploid and hexaploid Triticum species

Abstract

The genetic variations of high-molecularweight (HMW) glutenin subunits in 1051 accessions of 13 Triticum subspecies were investigated using sodium dodecyl sulfate polyacrylamide-gel electrophoresis. A total of 37 alleles were detected, resulting in 117 different allele combinations, among which 20, 68 and 29 combinations were observed in diploid, tetraploid and hexaploid wheats, respectively. Abundance and frequency of allele and combinations in tetraploid wheats were higher than these in hexaploid wheats. Allele Glu-A1c was the most frequent subunit at Glu-A1 locus in tetraploid and hexaploid wheats. Consequently, the results also suggested that the higher variations occurred at Glu-B1 locus compared to Glu-A1 and Glu-D1. Therefore, carthlicum wheat possessing the allele 1Ay could be presumed a special evolutional approach distinguished from other tetraploid species. Furthermore, this provides a convenient approach of induction of the 1Ay to common wheat through direct cross with carthlicum wheat. Alleles Glu-B1c and Glu-B1i generally absent in tetraploid wheats were also found in tetraploid wheats. Our results implied that tetraploid and hexaploid wheats were distinguished in dendrogram, whereas carthlicum and spelta wheats and however displayed the unique performance. In addition, founder effect, no-randomness of diploidization, mutation and artificial selection could cause allele distribution of HMW-GS in Triticum. All alleles of HMW-GS in Triticum could be further utilized through hybrid in the quality improvement of common wheat.

Allelic variation and distribution of HMW glutenin subunit 1Ay in Triticum species

“…Besides in the diploid T. urartu, T. boeoticum and T. monococcum (Ciaffi et al 1998;Ma et al 2007;Hu et al 2008), and the tetraploid T. dicoccoides Ciaffi et al 1993), T. carthlicum Nevski (Xu et al 2009), T. durum (Ciaffi et al 1991), T. dicoccon (Jiang et al 2009) and T. timopheevii Zhuk. (Wan et al 2002), the present study found that 1Ay subunit also existed in the tetraploids T. turgidum, T. polonicum and T. turanicum, and in the hexaploid T. zhukovskyi (Table 1).…”

“…The 1Ay subunit encoded by the y-type gene at Glu-1A locus has been deemed to be always silent in hexaploid wheat (Forde et al 1985;Halford et al 1989) with the exception of two Swedish bread wheat lines (Margiotta et al 1996). However, 1Ay subunit can express in some wild diploid (AA, 2n = 2x = 14) (Ciaffi et al 1998;Ma et al 2007;Hu et al 2008) and tetraploid wheat lines (AABB, 2n = 4x = 28) Ciaffi et al 1991;Ciaffi et al 1993;Wan et al 2002;Jiang et al 2009;Xu et al 2009). Some durum lines containing 1Ay subunit transferred from T. dicoccoides Körn.…”

Molecular characterization of differentTriticum monococcumssp.monococcum Glu-A1mxalleles

“…The Glu-A1 locus consists of two tightly linked genes that encode one larger x-type and one smaller y-type subunit, i.e., Glu-A1x and Glu-A1y. The 1Ay subunit is absent from common wheat because of gene silencing (Forde et al 1985;D'Ovidio et al 1996;Xu et al 2009;Hu et al 2012). However, the 1Ay subunit is expressed in wild relatives of wheat, such as T. urartu, T. monococcum ssp.…”

“…monococcum has high protein content and disease resistance for cultivated polyploid wheats (Lawrence et al 1958;Fedak 1985;Tranquilli et al 2002;Zaharieva and Monneveux 2014). Although the variability of the seed storage protein in this species has been characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), only two and three 1Ax alleles of Glu-A1 m x were detected by Xu et al (2009) and Alvarez et al (2006), respectively.…”

Identification of an active 1Ay gene from Triticum turgidum ssp. dicoccoides

“…In common wheat, the gene coding the subunit 1Ay is unexpressed because of a premature stop codon (Forde et al 1985) or the insertion of a transposon-like element within its coding region (Harberd et al 1987). However, this subunit is active in many lines of diploid wheat (AA) and the tetraploid wheats T. turgidum (AABB) and T. timopheevii (AAGG) (Ciaffi et al 1991(Ciaffi et al , 1998Ma et al 2007;Jiang et al 2009;Xu et al 2009;Hu et al 2012). Active 1Ay genes have been cloned from the wild diploid wheats T. urartu and T. monococcum ssp.…”