Molecular cloning of a novel chimeric HMW glutenin subunit gene 1Dx5′ from a common wheat line W958

Abstract

A novel chimeric high-molecular-weight (HMW) glutenin subunit gene from a new common wheat line W958 (2n=6x=42) was isolated and characterized. SDS–PAGE analysis revealed that this glutenin subunit has similar electrophoretic mobility
to 1Dx5, so it was designated 1Dx5′. Genomic DNA from W958 was amplified and a 2,505-bp fragment was obtained. The 1Dx5′ subunit
showed a chimeric primary structure of 1Dx5 and 1Dx2, with the 1Dx5 sequence in the 5′ and middle repetitive regions and the
1Dx2 sequence in the repetitive domain and 3′ region. MALDI-TOF-MS analysis demonstrated that 1Dx5′ had a molecular weight
of 86815.1Da, close to that of an x-type glutenin subunit. Secondary structure analysis showed that this subunit had six
helixes and one strand, including four helixes in the repetitive domain which could enhance the dough properties. Additionally,
the promoter of 1Dx5′ was obtained and showed the same sequence as 1Dx5 or 1Dx2 except for a few base conversions. The promoter analysis indicated that the cis-acting regulatory elements of 1Dx5′ were the same as those of 1Dx5 and/or 1Dx2. Previously, we have demonstrated that this novel glutenin subunit is associated with good bread-making quality and comprises
a very large proportion of the F2 segregation population. Consequently, we suggest that the amino acid residue composition
and the secondary structure of the subunit may contribute to the bread-making quality. In summary, the novel 1Dx5′ gene could have greater potential in wheat quality improvement.

KeywordsHMW glutenin subunit gene–
1Dx5′
–Secondary structure–Promoter–
Triticum aestivum L.