Nagaki K, Tsujimoto H, Sasakuma T
Kihara Institute Biological Research, Yokohama City University, 641-12 Maioka-cho, Totsuka-ku, Yokohama 244, Japan.
J Mol Evol. 1998 Aug;47(2):183-9. doi: 10.1007/pl00006375.
The Afa-family sequences in wheat-related species, Triticeae, are tandem repetitive sequences of 340 bp. All the analyzed Triticeae species carried the sequences in their genomes, though the copy numbers varied about 100-fold among the species. The nucleotide fragments amplified by PCR were cloned and sequenced, and their behavior in the evolution of Triticeae was analyzed by the neighbor-joining (NJ) method. The sequences in genomes with many copies of this family clustered at independent branches of the phylogenic tree, whereas the sequences in genomes with a few copies did not. This may suggest that Afa-family sequences had amplified several times in the evolution of Triticeae, each using a limited number of different master copies. In addition, the sequences of the A and B genomes of hexaploid common wheat indicated that the Afa-family sequences had not evolved in a concerted manner between the genomes. Furthermore, the sequences of each chromosome of the D genome of this species indicated that the sequences had amplified on all over the D-genome chromosomes in a short period.
在与小麦相关的物种——禾本科小麦族中，Afa家族序列是340 bp的串联重复序列。所有分析的小麦族物种在其基因组中都携带这些序列，尽管物种间的拷贝数相差约100倍。通过PCR扩增的核苷酸片段被克隆并测序，并通过邻接法（NJ）分析它们在小麦族进化中的行为。该家族多拷贝基因组中的序列聚集在系统发育树的独立分支上，而少拷贝基因组中的序列则不然。这可能表明Afa家族序列在小麦族进化过程中经历了多次扩增，每次扩增使用数量有限的不同主拷贝。此外，六倍体普通小麦A和B基因组的序列表明，Afa家族序列在两个基因组之间并非协同进化。此外，该物种D基因组各染色体的序列表明，这些序列在短时间内在整个D基因组染色体上都发生了扩增。
