Characterization of HMW-GSs and their gene inaction in tetraploid wheat.
In this study, we report the expression of HMW-GSs in 87 accessions of tetraploid wheat, the characterization of three inactive and one active HMW glutenin genes, and the functional verification of HMW-GSs by promoter-GUS expression. SDS-PAGE profiles revealed that tetraploid wheat has many different combinations of HMW-GSs and the number of subunits varies from 1 to 4. HMW glutenin genes at the Glu-A1x, Glu-A1y and Glu-B1y loci exhibited different frequencies of inaction while the Glu-B1x allele was expressed in all 87 accessions. Gene cloning showed that only 1Bx (Tdu-e) could express a full-length protein and its deduced protein sequence has the typical primary structure but with fewer cysteine residues. The expression of the other three HMW glutenin genes has been disrupted by stop codons in their repetitive domains. Besides short indels or mutations of one or more bases, an 85-bp deletion and a 185-bp insertion were found in the promoter regions of 1Ay (Tdu-s) and 1Bx (Tdu-e). The transient expression of promoter-GUS constructs indicated that the 1Ay promoter can drive expression of the GUS gene. We conclude that defects (stop codons or the insertion of large transposon-like elements) in the coding regions may be the most probable cause for the inaction of the HMW glutenin genes.
Triticeae Research Institute, Sichuan Agricultural University, Chengdu 611130, Sichuan, China.
Qian-Tao
QT
Jiang
Jian
J
Ma
Shan
S
Zhao
Quan-Zhi
QZ
Zhao
Xiu-Jin
XJ
Lan
Shou-Fen
SF
Dai
Zhen-Xiang
ZX
Lu
You-Liang
YL
Zheng
Yu-Ming
YM
Wei
D003001:Cloning, Molecular; D018744:DNA, Plant / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D017343:Genes, Plant; D005983:Glutens / Q000235:genetics*; D008970:Molecular Weight; D010802:Phylogeny; D057891:Tetraploidy; D014908:Triticum / Q000235:genetics*
D018744:DNA, Plant; D005983:Glutens; C037302:glutenin