Polymorphisms in two homeologous γ-gliadin genes and the evolution of cultivated wheat
Polymorphisms in two homeologous γ-gliadin genes and the evolution of cultivated wheat
复制标题
DOI：
10.1023/a:1011213228222
复制
发表时间：
2001-04-01
影响因子：
2
通讯作者：
von Büren, M
中科院分区：
文献类型：
--
作者：
von Büren, M
利用PCR产物测序和PCR-RFLP技术，对多倍体小麦D、B基因组上的γ-醇溶蛋白基因GAG 56 D和GAG 56 B的多态性进行了研究。GAG 56 D的两个等位基因fo和ok先前已知发生在六倍体小麦中。在这里，我们发现，16个测序片段的GAG 56 D从6个公认的亚种小麦，包括13本研究贡献的，是相同的，无论是fo或ok等位基因。考虑到已发表的证据，得出的结论是，所调查的等位基因GAG 56 D源于两个不同的节节麦植物，因此两个独立的起源六倍体小麦。与从10份Ae. tauschii，fo和ok等位基因与里海地区收集的三个品种的片段聚在一起。通过对GAG 56 B片段的测序，在栽培小麦中发现了4个不同的等位基因群，分别为典型的面包小麦（p-aes）、醇溶蛋白45型的硬粒小麦（a）、醇溶蛋白42型的硬粒小麦（p-dur）和麦谷夫小麦（p-tim）。有趣的是，在醇溶蛋白45型硬粒小麦中发现的等位基因被欧洲斯佩耳特小麦品种所共有，这强烈支持了欧洲斯佩耳特小麦起源于四倍体和六倍体小麦之间的杂交事件的假设。数据还表明，二粒小麦可能被驯化了不止一次。对从推定的B/G基因组供体获得的GAG 56片段的系统发育分析排除了作为B/G基因组直接供体的所有候选物种，而是表明在多倍体小麦中发现的所有GAG 56 B等位基因的单系起源，即包括T. timopheevii。
The polymorphisms in two gamma -gliadin genes GAG56D and GAG56B on the D- and B-genomes of polyploid wheat, respectively, were investigated by sequencing PCR products and by PCR-RFLP. Of GAG56D, two alleles fo and ok were previously known to occur in hexaploid wheat. Here, we found that 16 sequenced fragments of GAG56D from six recognized subspecies of Triticum aestivum, including 13 contributed by this study, were identical to either the fo or the ok allele. Considering published evidence, it was concluded that the investigated alleles of GAG56D stemmed from two different Aegilops tauschii plants and thus two independent origins of hexaploid wheat. Compared to GAG56D-sequences obtained from 10 accessions of Ae. tauschii, the fo and ok alleles clustered with fragments from three accessions collected in the Caspian region. By sequencing fragments of GAG56B, four distinct allelic groups were found among cultivated wheats, typical of bread wheat (p-aes), durum wheat of gliadin 45-type (a), durum wheat of gliadin 42-type (p-dur) and Timopheev's wheat (p-tim), respectively. Interestingly, the a allele found in gliadin 45-type durum wheat was shared by European spelt cultivars, which strongly supported the hypothesis that European spelt originated from a hybridization event between a tetra- and hexaploid wheat. The data also suggested that emmer might have been domesticated more than once. Phylogenetic analysis of GAG56-fragments obtained from putative B/G-genome donors excluded all candidate species as immediate donors of the B/G-genome, but instead indicated a monophyletic origin of all GAG56B alleles found in polyploid wheat, i.e. including T. timopheevii.