Gene movement by Helitron transposons contributes to the haplotype variability of maize
Gene movement by Helitron transposons contributes to the haplotype variability of maize
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DOI：
10.1073/pnas.0502923102
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发表时间：
2005-06-21
影响因子：
11.1
通讯作者：
Dooner, HK
中科院分区：
文献类型：
--
作者：
Lai, JS;Li, YB;Dooner, HK
不同的玉米自交系在不同的等位基因染色体位置上基因序列的存在或不存在是多态的。在位于9 S的bz基因组区域中，与来自水稻和拟南芥的四个不同基因同源的序列存在于McC系中，但不存在于B73系中。它在这里表明，这种明显的种内违反遗传共线性产生的基因或基因片段的运动Helitrons，最近发现的一类真核转座子。两个Helitrons，HelA和HelB，占区分两个bz位点单倍型的所有基因差异。HelA长5.9kb，包含仅在McC bz基因组区域中发现的四个基因中的三个的序列。从B73中的5S染色体位置分离出几乎相同的HelA拷贝。95和55位点在玉米中表现出多态性，表明这些Helitrons最近一直很活跃。Helitron缺乏其他转座子的强预测性末端特征，因此通过在Helitron-minus系中鉴定其空缺位点来极大地促进其末端的定义。通过McC单倍型序列与第三个品系Mo 17的单倍型序列的比较，可以辨别出2.7-kb HelB Helitron的末端，因为HelB空位在B73中缺失。玉米Helitrons类似于水稻Pack-MULE，它们能够从几个位点捕获基因或基因片段并将它们在基因组中移动，这些特征赋予它们在基因进化中的潜在作用。
Different maize inbred lines are polymorphic for the presence or absence of genic sequences at various allelic chromosomal locations. In the bz genomic region, located in 9S, sequences homologous to four different genes from rice and Arabidopsis are present in line McC but absent from line B73. It is shown here that this apparent intraspecific violation of genetic colinearity arises from the movement of genes or gene fragments by Helitrons, a recently discovered class of eukaryotic transposons. Two Helitrons, HelA and HelB, account for all of the genic differences distinguishing the two bz locus haplotypes. HelA is 5.9 kb long and contains sequences for three of the four genes found only in the McC bz genomic region. A nearly identical copy of HelA was isolated from a 5S chromosomal location in B73. Both the 95 and 55 sites appear to be polymorphic in maize, suggesting that these Helitrons have been active recently. Helitrons lack the strong predictive terminal features of other transposons, so the definition of their ends is greatly facilitated by the identification of their vacant sites in Helitron-minus lines. The ends of the 2.7-kb HelB Helitron were discerned from a comparison of the McC haplotype sequence with that of yet a third line, Mo17, because the HelB vacant site is deleted in B73. Maize Helitrons resemble rice Pack-MULEs in their ability to capture genes or gene fragments from several loci and move them around the genome, features that confer on them a potential role in gene evolution.