Haplotype structure strongly affects recombination in a maize genetic interval polymorphic for Helitron and retrotransposon insertions
Haplotype structure strongly affects recombination in a maize genetic interval polymorphic for Helitron and retrotransposon insertions
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DOI：
10.1073/pnas.0902972106
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发表时间：
2009-05-26
影响因子：
11.1
通讯作者：
Dooner, Hugo K.
中科院分区：
文献类型：
--
作者：
He, Limei;Dooner, Hugo K.
我们在这里已经问了玉米单倍型结构的显著变化是如何影响重组的。我们比较了重组跨越遗传间隔的9 S在2个高度不同的杂合子，共享1个父母。常见单倍型的遗传间隔约为100 kb长，包含6个基因，其中散布着基因片段携带的Helitron和反转录转座子，它们共同占其长度的70%。在一个杂合子中，大多数基因间插入是纯合的，虽然多态性，使我们能够确定是否有任何重组连接属于他们。在另一种情况下，大多数基因间插入是半合子的，因此不能进行同源重组。我们的分析频率和分布的重组的时间间隔显示：（i）大多数路口外接的基因空间，在那里他们表现出高度不均匀的分布。在这两个杂合子中，超过一半的连接点都落在stc 1基因上，使其成为该区域明显的重组热点。然而，stc 1的遗传大小是2倍低时，两侧的半合子25-kb反转录转座子簇。(ii)在两个杂合子中，hypro 1基因都没有连接点，这使其成为基因重组冷点。(iii)Helitrons上的基因片段和反转录转座子内都没有发生重组，因此插入类对间隔的遗传长度都没有贡献。(iv)出乎意料的是，几个连接点位于并非所有3种单倍型共有的基因间区域。(v)一般来说，序列重组的能力与其甲基化状态呈负相关。我们的研究结果表明，单倍型结构变异强烈影响的频率和分布的重组事件在玉米。
We have asked here how the remarkable variation in maize haplotype structure affects recombination. We compared recombination across a genetic interval of 9S in 2 highly dissimilar heterozygotes that shared 1 parent. The genetic interval in the common haplotype is approximate to 100 kb long and contains 6 genes interspersed with gene-fragment-bearing Helitrons and retrotransposons that, together, comprise 70% of its length. In one heterozygote, most intergenic insertions are homozygous, although polymorphic, enabling us to determine whether any recombination junctions fall within them. In the other, most intergenic insertions are hemizygous and, thus, incapable of homologous recombination. Our analysis of the frequency and distribution of recombination in the interval revealed that: (i) Most junctions were circumscribed to the gene space, where they showed a highly nonuniform distribution. In both heterozygotes, more than half of the junctions fell in the stc1 gene, making it a clear recombination hotspot in the region. However, the genetic size of stc1 was 2-fold lower when flanked by a hemizygous 25-kb retrotransposon cluster. (ii) No junctions fell in the hypro1 gene in either heterozygote, making it a genic recombination coldspot. (iii) No recombination occurred within the gene fragments borne on Helitrons nor within retrotransposons, so neither insertion class contributes to the interval's genetic length. (iv) Unexpectedly, several junctions fell in an intergenic region not shared by all 3 haplotypes. (v) In general, the ability of a sequence to recombine correlated inversely with its methylation status. Our results show that haplotypic structural variability strongly affects the frequency and distribution of recombination events in maize.