植物细胞遗传图及其应用

细胞遗传图（cytogenetic map）综合了来自遗传图（genetic map）和细胞学图（cytological map）两方面的信息，它既能反映基因或DNA标记之间在染色体上的真实距离，又能显示它们与染色体的细胞学结构间确切的位置关系。构建植物细胞遗传图的宗旨是将遗传图上的诸多标记与其在染色体的具体位置联系起来。目前主要有两种方法用于细胞遗传图的构建。较广泛使用的一种方法是借助染色体断点来确定遗传标记在染色体上的位置，另一种方法是利用荧光原位杂交（FISH）直接把DNA序列定位到染色体上。此外，利用RN-cM图也可以把遗传标记定位于粗线期染色体。从细胞遗传图可以看出，染色体两臂的远端有较高的基因密度和重组频率。细胞遗传图在比较近缘植物基因组的同线性、揭示植物的进化关系、研究基因定位克隆等方面都有重要意义.

Cytogenetic Maps and their Applications in Plants

Integrated cytogenetic maps encompass the information from both genetic maps and cytological maps. It is possible for cytogenetic maps to simultaneously report the cytological and genetic position of a maker. To constructure cytogenetic maps it is necessary to relate the markers mapped across linkage groups to cytological position on chromosomes. Cytogenetic maps have been constructured primarily in two ways. The first general strategy is to utilize the chromosome breakpoints to determine the location of genetically mapped markers on the chromosomes. A second way is by the direct hybridization of genetically mapped sequences onto chromosomes by FISH. In addition, a novel approach is to use RN-cM maps to predict the physical position of genetic markers on the chromosomes. Cytogenetic maps suggest that both the density of genes and the frequency of recombination increase towards the distal regions of chromosome arms, and they play significant roles in revealing gene colinearity between two species, exploring the evolution relationship between both of them and in map-based gene isolation.