科研之友
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摘要
Two new x-type high-molecular-weight glutenin subunits with similar size to 1Dx5, designated 1Dx5*(t) and 1Dx5*(t) in Aegilops tauschii, were identified by SDS-PAGE, RP-HPLC, and MALDI-TOF-MS. The coding sequences were isolated by AS-PCR and the complete ORFs were obtained. Allele 1Dx5*(t) consists of 2481 bp encoding a mature protein of 827 residues with deduced M-r of 85,782 Da whereas 1Dx5*(t) comprises 2526 bp encoding 842 residues with M-r of 87,663 Da. The deduced M-r's of both genes were consistent, with those determined by MALDI-TOF-MS. Molecular structure analysis showed that the repeat motifs of 1Dx5*(t) were correspondingly closer to the consensus compared to 1Dx5*(t) and 1Dx5 subunits. A total of 11 SNPs (3 in 1Dx5*(t) and 8 in 1Dx5.1*(t)) and two indels in 1Dx5*(t) were identified, amongwhich 8 SNPs were due to C-T or A-G transitions (an average of 73%). Expression of the cloned ORFs and N-terminal sequencing confirmed the authenticities of the two genes. Interestingly, several hybrid clones of 1Dx5*(t) expressed a slightly smaller protein relative to the authentic subunit present in seed proteins; this was confirmed to result from a deletion of 180 bp through illegitimate recombination as well as an in-frame stop codon. Network analysis demonstrated that 1Dx5*(t), 1Dx2(t), 1Dx1.6(t) and 1Dx2.2* represent a root within a network and correspond to the common ancestors of the other Glu-D-1-1 alleles in an associated star-like phylogeny, suggesting that there were at least four independent origins of hexaploid wheat. In addition to unequal homologous recombination, duplication and deletion of large fragments occurring in Glu-D-1-1 alleles were attributed to illegitimate recombination.
- 出版日期2008-1
- 单位首都师范大学
