Dynamic nature of a wheat centromere with a functional gene
Dynamic nature of a wheat centromere with a functional gene
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DOI：
10.1007/s11032-009-9389-1
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发表时间：
2010-08-01
影响因子：
3.1
通讯作者：
Gill, Kulvinder S.
中科院分区：
文献类型：
--
作者：
Mutti, Jasdeep S.;Sandhu, Devinder;Gill, Kulvinder S.
高等真核生物的着丝粒区主要由串联和非串联重复序列组成，这些序列具有可变的拷贝数、间距、顺序和方向；在本质上是异色的，并且被认为是缺乏积极转录的基因。在这里，我们报道了一个活跃转录的小麦同源HSP70基因，该基因位于功能性小麦着丝粒中，其拷贝数似乎随着着丝粒断裂而改变。HSP70基因物理定位在中国春（CS）的1A和1D染色体短臂和黑麦的1R染色体上。然而，在‘CS’和Pavon背景下的1B染色体上，该基因定位于功能性着丝粒，这一点从细胞学上证实的真二染色体系Dt1BS和Dt1BL中都可以看出。11个ESTs序列比较显示三种序列模式，表明该基因的三个同源拷贝均有表达。cdna -单链构象多态性分析证实了该基因‘CS’ 1B拷贝的表达。在两个独立发育的Dt1BL系中观察到，该基因的1B拷贝数在着丝粒周围的染色体断裂时显示出3到5倍的增加。假定的基因重复似乎涉及较大的染色体片段，因为用于DNA凝胶印迹分析的10种限制性内切酶中只有一种在Dt1BL系中显示出独特的额外片段带。有必要进一步调查以揭示这些重复的性质和机制。
Centromeric regions of higher eukaryotes are comprised mainly of tandem and non-tandem repeat sequences with variable copy number, spacing, order and orientation; are heterochromatic in nature, and are believed to be devoid of actively transcribing genes. Here, we report an actively transcribing wheat homolog of HSP70 gene that maps in the functional wheat centromere, and copy number of which seems to change in response to centromeric breaks. The HSP70 gene physically maps on the short arm of chromosomes 1A and 1D of Chinese Spring (CS) and 1R of rye. Whereas, on chromosome 1B in both 'CS' and Pavon background, the gene maps in the functional centromere as evident from its presence in both cytologically confirmed true ditelosomic lines Dt1BS and Dt1BL. Sequence comparison of 11 ESTs showed three sequence patterns suggesting that all three homoeologous copies of the gene are expressing. The cDNA-single stranded conformation polymorphism analysis confirmed expression of the 'CS' 1B copy of the gene. Observed in two independently developed Dt1BL lines, the 1B copy number of the gene showed three to fivefold increase in response to chromosomal breaks around the centromere. Putative gene duplications seem to involve large chromosomal segments as only one of the ten restriction enzymes used for DNA gel-blot analysis showed unique extra fragment band in the Dt1BL line. Further investigations are warranted to uncover the nature and mechanism of these duplications.