STRUCTURE, FUNCTION AND CHROMOSOME LOCATION OF THE NOVEL MULTIGENE FAMILY IN THE GENOME OF TRITICEAE SPECIES

在小麦族基因组中发现了一类新的长度为3kb的转座因子。该转座子含有编码118个氨基酸残基的转座酶的单个ORF，其由经加工的mRNA（726 nt）赋予。首先，通过黑麦和小麦之间的共有DNA序列的基因组消减，分离出在黑麦基因组中富集的转座子的部分DNA片段（89 bp）。然后，通过对包括89 bp片段的基因组克隆进行测序来确定黑麦基因组特异性元件的整个结构。该元件的共有序列全长3041 bp，在黑麦基因组中分散存在，两端各有20 bp的末端反向重复序列。通过北方分析，转座子样元件被活跃地转录。此外，在小麦族植物中克隆了该转座子的cDNA（726 bp），表明该转座子含有3个外显子（342 bp，88 bp，296 bp）和2个内含子（750 bp，1，237 bp）。由于转座子的整个结构与已知的转座因子不相同，因此将其命名为Revolver。Revolver的推导基因编码一种具有转录调节功能的蛋白质，具有DNA结合能力。对小麦族植物的基因组Southern印迹显示，Revolver在小麦近缘种黑麦、簇毛麦以及小麦祖先种一粒小麦和山羊草的基因组中丰富。squarrosa。至少有一万个左轮手枪拷贝沿着小麦近缘种的每条染色体分布。然而，左轮手枪是相当罕见的面包小麦品种。这些事实表明，左轮手枪已经存在的进化，从小麦的祖先，然后它一直在一些物种中扩增，而在面包小麦消失。Revolver是一类新的转座子类基因，可用于小麦近缘种的DNA标记和系统进化研究

A new class of transposable element with 3 kb length have been identified in the Triticeae genome. The transposon contains a single ORF of a transposase encoding 118 amino acid residues, which is conferred by a processed mRNA (726 nt). Firstly, a partial DNA fragment (89 bp) of the transposon enriched in the rye genome was isolated via the genomic subtraction of common DNA sequences between rye and wheat. Then, the whole structure of the rye genome-specific element is determined by sequencing genomic clones, which include the 89 bp segment. The consensus sequence of the element encompasses 3041 bp and it exists dispersedly in the rye genome by flanking with 20 bp of terminal inverted repeated sequence in the both ends. The transposon-like element is actively transcribed by Northern analysis. Moreover, cDNA clones (726 bp) derived from the transposon has identified in Triticeae plants, elucidating that the transposon bears 3 exons (342 bp, 88 bp, 296 bp) and 2 introns (750 bp, 1,237 bp). The entire structure of the transposon dose not share identity with known transposable elements, then the transposon is designated as Revolver. The deduced gene of Revolver encodes a protein featuring transcriptional regulators, having DNA binding ability. Genomic Southern blots on the Triticeae plants revearls that Revolver is abundant in the genomes of wheat relatives, rye, Dasypyrum, as well as wheat ancestor species, T.monococcum and Ae. squarrosa. At least ten thousand copies of Revolver are distributed along with each chromosome of wheat relatives. However, Revolver is quite rare in bread wheat varieties. These facts indicates that Revolver have been existed through the evolution since the ancestor of wheat, then it has been amplifing in some species, while disappearing in bread wheat. A new class of transposon-like gene Revolver is effective to develop DNA markers for wild wheat relatives, useful gene sources of wheat, and to evaluate phylogenetic evolution among the Triticeae