A high-molecular-weight glutenin subunit gene1Dx2.1from Xinjiang rice wheat

Abstract

Xinjiang rice wheat (Triticum petropavlovskyi Udacz. et Migush, 2n=6x=42, AABBDD) is one of the endemic Chinese wheats, only distributing in Xinjiang and Xizang (Tibet), China. A novel high-molecular-weight (HMW) glutenin subunit gene 1DX2.1 was isolated and characterized from Xinjiang rice wheat accession Daomai2. The complete open reading frame (ORF) of 1Dx2.1 is 2508 bp, encoding 836 amino acids. The primary structure of 1DX2.1 consists of three distinct domains, a non-repetitive N-terminal domain with 89 residues, a non-repetitive C-terminal domain with 42 residues and a large central repetitive domain with 684 residues. In the N-terminal of 1DX2.1, there is an R (arginine) at position 75, whereas there is a Q (glutamine) in other known x-type subunits. Four cysteine residues are observed in 1DX2.1 with three in the N-terminal region and one in the C-terminal region. The number and distribution of cysteines in 1DX2.1 are identical to those in x-type subunits except for 1DX5, which possesses an extra cysteine residue. Differences between the repetitive domain of 1DX2.1 and those of known HMW subunits resulted from substitutions, insertions or/and deletions involving single or more amino acid residues. The phylogenetic tree, which was constructed on the basis of amino acid sequences, and indicated that 1DX2.1 was highly related to 1Dx2.lt, then to 1DX2 and 1DX5.