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Characterization and comparative analysis of HMW glutenin 1Ay alleles with differential expressions.

Jiang QT, Wei YM, Wang F, Wang JR, Yan ZH, Zheng YL - BMC Plant Biol. (2009)

Bottom Line: The 85 bp deletions have been found in promoter regions of all 1Ay genes and the corresponding positions of 6 species from Aegilops and Hordeum.The 85 bp deletion and some variations in the 5'flanking region, have not interrupted expression of 1Ay genes, whereas the defects in the coding regions could be responsible to the silence of the 1Ay genes.Some mutational events in more distant distal promoter regions are also possible causes for the inactivation of 1Ay genes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Triticeae Research Institute, Sichuan Agricultural University, Ya'an, Sichuan, 625014, PR China. qiantaojiang@hotmail.com

ABSTRACT

Background: High-molecular-weight glutenin subunits (HMW-GSs) have been considered as most important seed storage proteins for wheat flour quality. 1Ay subunits are of great interest because they are always silent in common wheat. The presence of expressed 1Ay subunits in diploid and tetraploid wheat genotypes makes it possible to investigate molecular information of active 1Ay genes.

Results: We identified 1Ay subunits with different electrophoretic mobility from 141 accessions of diploid and tetraploid wheats, and obtained the complete ORFs and 5' flanking sequences of 1Ay genes including 6 active and 3 inactive ones. Furthermore, the 5' flanking sequences were characterized from 23 wild diploid species of Triticeae. All 6 active 1Ay possess a typical HMW-GS primary structure and some novel characteristics. The conserved cysteine residue within the repetitive domain of y-type subunits was replaced by phenylalanine residue in subunits of 1Ay (Tu-e1), 1Ay (Tu-e2), 1Ay (Ta-e2) and 1Ay (Td-e). Particularly, 1Ay (Ta-e3) has an unusual large molecular weight of 2202 bp and was one of the known largest y-type HMW-GSs. The translations of 1Ay (Tu-s), 1Ay (Ta-s) and 1Ay (Td-s) were disrupted by premature stop codons in their coding regions. The 5' flanking sequences of active and inactive 1Ay genes differ in a few base substitutions and insertions or deletions. The 85 bp deletions have been found in promoter regions of all 1Ay genes and the corresponding positions of 6 species from Aegilops and Hordeum.

Conclusion: The possession of larger molecular weight and fewer conserved cysteine residues are unique structural features of 1Ay genes; it would be interested to express them in bread wheat and further to examine their impact to processing quality of wheat. The 1Ay genes from T. urartu are closer to the genes from T. turgidum dicoccon and T. aestivum, than those from T. monococcum aegilopoides. The 85 bp deletion and some variations in the 5'flanking region, have not interrupted expression of 1Ay genes, whereas the defects in the coding regions could be responsible to the silence of the 1Ay genes. Some mutational events in more distant distal promoter regions are also possible causes for the inactivation of 1Ay genes.

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Comparison of the primary structure of 1Ay subunits from different wheat species. Signal peptide was underlined; N-terminal and C-terminal regions were boxed, respectively. Conserved cysteine residues were indicated by solid arrows while the substitutions of cysteine residues with phenylalanine residue (F) were marked by hollow arrows. The in-frame stop codons were represented by asterisks and boxed.
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Figure 3: Comparison of the primary structure of 1Ay subunits from different wheat species. Signal peptide was underlined; N-terminal and C-terminal regions were boxed, respectively. Conserved cysteine residues were indicated by solid arrows while the substitutions of cysteine residues with phenylalanine residue (F) were marked by hollow arrows. The in-frame stop codons were represented by asterisks and boxed.

Mentions: After translating the DNA into protein sequences, analysis of amino acid sequence indicated that the ORFs of 6 active 1Ay genes possess a typical primary structure shared by other published HMW-GSs, although these subunits differ greatly in sizes (Figure 3 and Table 1). Each of these deduced subunits consists of a signal peptide with 21 amino acids (aa), a conserved N-terminal region, a central repetitive domain and a C-terminal region. The N-terminal regions of these 6 subunits contain 104 aa and the C-terminal regions have 42 aa. Central repetitive domains of these subunits are composed of a similar repeat structure to other known y-type subunits. The subunit 1Ay (Ta-e3) is composed of 732 aa, larger than all other known y-type HMW-GSs. The difference between 1Ay (Ta-e3) and other y-type HMW-GSs were entirely due to variations of the number of repeat motifs. Compared to other 1Ay subunits, 13 extra hexapeptides and 5 extra nonapeptides have been inserted into the repetitive domain of 1Ay (Ta-e3), which resulted in 123 aa increases in its molecular mass.


Characterization and comparative analysis of HMW glutenin 1Ay alleles with differential expressions.

Jiang QT, Wei YM, Wang F, Wang JR, Yan ZH, Zheng YL - BMC Plant Biol. (2009)

Comparison of the primary structure of 1Ay subunits from different wheat species. Signal peptide was underlined; N-terminal and C-terminal regions were boxed, respectively. Conserved cysteine residues were indicated by solid arrows while the substitutions of cysteine residues with phenylalanine residue (F) were marked by hollow arrows. The in-frame stop codons were represented by asterisks and boxed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2667398&req=5

Figure 3: Comparison of the primary structure of 1Ay subunits from different wheat species. Signal peptide was underlined; N-terminal and C-terminal regions were boxed, respectively. Conserved cysteine residues were indicated by solid arrows while the substitutions of cysteine residues with phenylalanine residue (F) were marked by hollow arrows. The in-frame stop codons were represented by asterisks and boxed.
Mentions: After translating the DNA into protein sequences, analysis of amino acid sequence indicated that the ORFs of 6 active 1Ay genes possess a typical primary structure shared by other published HMW-GSs, although these subunits differ greatly in sizes (Figure 3 and Table 1). Each of these deduced subunits consists of a signal peptide with 21 amino acids (aa), a conserved N-terminal region, a central repetitive domain and a C-terminal region. The N-terminal regions of these 6 subunits contain 104 aa and the C-terminal regions have 42 aa. Central repetitive domains of these subunits are composed of a similar repeat structure to other known y-type subunits. The subunit 1Ay (Ta-e3) is composed of 732 aa, larger than all other known y-type HMW-GSs. The difference between 1Ay (Ta-e3) and other y-type HMW-GSs were entirely due to variations of the number of repeat motifs. Compared to other 1Ay subunits, 13 extra hexapeptides and 5 extra nonapeptides have been inserted into the repetitive domain of 1Ay (Ta-e3), which resulted in 123 aa increases in its molecular mass.

Bottom Line: The 85 bp deletions have been found in promoter regions of all 1Ay genes and the corresponding positions of 6 species from Aegilops and Hordeum.The 85 bp deletion and some variations in the 5'flanking region, have not interrupted expression of 1Ay genes, whereas the defects in the coding regions could be responsible to the silence of the 1Ay genes.Some mutational events in more distant distal promoter regions are also possible causes for the inactivation of 1Ay genes.

View Article: PubMed Central - HTML - PubMed

Affiliation: Triticeae Research Institute, Sichuan Agricultural University, Ya'an, Sichuan, 625014, PR China. qiantaojiang@hotmail.com

ABSTRACT

Background: High-molecular-weight glutenin subunits (HMW-GSs) have been considered as most important seed storage proteins for wheat flour quality. 1Ay subunits are of great interest because they are always silent in common wheat. The presence of expressed 1Ay subunits in diploid and tetraploid wheat genotypes makes it possible to investigate molecular information of active 1Ay genes.

Results: We identified 1Ay subunits with different electrophoretic mobility from 141 accessions of diploid and tetraploid wheats, and obtained the complete ORFs and 5' flanking sequences of 1Ay genes including 6 active and 3 inactive ones. Furthermore, the 5' flanking sequences were characterized from 23 wild diploid species of Triticeae. All 6 active 1Ay possess a typical HMW-GS primary structure and some novel characteristics. The conserved cysteine residue within the repetitive domain of y-type subunits was replaced by phenylalanine residue in subunits of 1Ay (Tu-e1), 1Ay (Tu-e2), 1Ay (Ta-e2) and 1Ay (Td-e). Particularly, 1Ay (Ta-e3) has an unusual large molecular weight of 2202 bp and was one of the known largest y-type HMW-GSs. The translations of 1Ay (Tu-s), 1Ay (Ta-s) and 1Ay (Td-s) were disrupted by premature stop codons in their coding regions. The 5' flanking sequences of active and inactive 1Ay genes differ in a few base substitutions and insertions or deletions. The 85 bp deletions have been found in promoter regions of all 1Ay genes and the corresponding positions of 6 species from Aegilops and Hordeum.

Conclusion: The possession of larger molecular weight and fewer conserved cysteine residues are unique structural features of 1Ay genes; it would be interested to express them in bread wheat and further to examine their impact to processing quality of wheat. The 1Ay genes from T. urartu are closer to the genes from T. turgidum dicoccon and T. aestivum, than those from T. monococcum aegilopoides. The 85 bp deletion and some variations in the 5'flanking region, have not interrupted expression of 1Ay genes, whereas the defects in the coding regions could be responsible to the silence of the 1Ay genes. Some mutational events in more distant distal promoter regions are also possible causes for the inactivation of 1Ay genes.

Show MeSH
Related in: MedlinePlus