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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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PCR amplification of HMW-GS ORFs. Lane1–3: PI 428309, PI 428318, PI 428308 (T. urartu); lane 4–7: PI 428007, PI 277123, PI 306526, PI 427928 (T. monococcum aegilopoides) and lane 8 and 9: PI355475, PI355477 (T. turgidum dicoccon); M is 1 Kb DNA ladder.
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Figure 2: PCR amplification of HMW-GS ORFs. Lane1–3: PI 428309, PI 428318, PI 428308 (T. urartu); lane 4–7: PI 428007, PI 277123, PI 306526, PI 427928 (T. monococcum aegilopoides) and lane 8 and 9: PI355475, PI355477 (T. turgidum dicoccon); M is 1 Kb DNA ladder.

Mentions: In genomic PCR, there is only one amplified fragment in each of T.urartu and T.monococcum aegilopoides, whereas 4 fragments were amplified in 2 T.turgidum dicoccon accessions. The amplified fragments in T. urartu and T.monococcum aegilopoides ranged from1800 to 2202 bp (Figure 2). It is close to the size of those typical y-type HMW-GS genes except for the fragment of 2202 bp. In T.turgidum dicoccon accessions, the molecular weight of fragments is between 1.8 and 2.5 kb (Figure 2). All amplified products were cloned. By terminal sequencing and enzyme digestions, the ORFs representing different 1Ay alleles were determined. The full length sequences of 1Ay ORFs were obtained by using the method of nested deletion. The 9 sequences were named as 1Ay (Tu-e1), 1Ay (Tu-e2) and 1Ay (Tu-s) to represent the ORFs of 1Ay subunits from T. urartu;1Ay (Ta-e1), 1Ay (Ta-e2), 1Ay (Ta-e3) and 1Ay (Ta-s) to represent the ORFs of 1Ay subunits from T. monococcum aegilopoides; and 1Ay (Td-e) and 1Ay (Td-s) to represent the ORFs of 1Ay subunits from T.turgidum dicoccon (the letter e and s represent the expressed and silenced subunits, the numbers represent different alleles.). All sequences were deposited in NCBI database with Genbank accession numbers from:EU984503 to EU984511.


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)

PCR amplification of HMW-GS ORFs. Lane1–3: PI 428309, PI 428318, PI 428308 (T. urartu); lane 4–7: PI 428007, PI 277123, PI 306526, PI 427928 (T. monococcum aegilopoides) and lane 8 and 9: PI355475, PI355477 (T. turgidum dicoccon); M is 1 Kb DNA ladder.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: PCR amplification of HMW-GS ORFs. Lane1–3: PI 428309, PI 428318, PI 428308 (T. urartu); lane 4–7: PI 428007, PI 277123, PI 306526, PI 427928 (T. monococcum aegilopoides) and lane 8 and 9: PI355475, PI355477 (T. turgidum dicoccon); M is 1 Kb DNA ladder.
Mentions: In genomic PCR, there is only one amplified fragment in each of T.urartu and T.monococcum aegilopoides, whereas 4 fragments were amplified in 2 T.turgidum dicoccon accessions. The amplified fragments in T. urartu and T.monococcum aegilopoides ranged from1800 to 2202 bp (Figure 2). It is close to the size of those typical y-type HMW-GS genes except for the fragment of 2202 bp. In T.turgidum dicoccon accessions, the molecular weight of fragments is between 1.8 and 2.5 kb (Figure 2). All amplified products were cloned. By terminal sequencing and enzyme digestions, the ORFs representing different 1Ay alleles were determined. The full length sequences of 1Ay ORFs were obtained by using the method of nested deletion. The 9 sequences were named as 1Ay (Tu-e1), 1Ay (Tu-e2) and 1Ay (Tu-s) to represent the ORFs of 1Ay subunits from T. urartu;1Ay (Ta-e1), 1Ay (Ta-e2), 1Ay (Ta-e3) and 1Ay (Ta-s) to represent the ORFs of 1Ay subunits from T. monococcum aegilopoides; and 1Ay (Td-e) and 1Ay (Td-s) to represent the ORFs of 1Ay subunits from T.turgidum dicoccon (the letter e and s represent the expressed and silenced subunits, the numbers represent different alleles.). All sequences were deposited in NCBI database with Genbank accession numbers from:EU984503 to EU984511.

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