Kubisiak Thomas L, Milgroom Michael G
USDA Forest Service, Southern Research Station, Southern Institute of Forest Genetics, 23332 Hwy 67, Saucier, MS 39574, USA.
Fungal Genet Biol. 2006 Jun;43(6):453-63. doi: 10.1016/j.fgb.2006.02.002. Epub 2006 Mar 22.
To find markers linked to vegetative incompatibility (vic) genes in the chestnut blight fungus, Cryphonectria parasitica, we constructed a preliminary linkage map. In general, this map is characterized by low levels of polymorphism, as evident from the more than 24 linkage groups observed, compared to seven expected from electrophoretic karyotyping. Nonetheless, we found markers closely linked to two vic genes (vic1 and vic2) making them candidates for positional cloning. Two markers were found to be linked to vic2: one cosegregated with vic2, i.e., it is 0.0 cM from vic2, the other was at a distance of 4.5 cM; a single marker was found 4.0 cM from vic1. The closest markers linked to three other vic genes (vic4, vic6, and vic7) were >15 cM away; additional markers are needed before efficient positional cloning of these three vic genes can be realized. In contrast to the low levels of polymorphism observed across most of the C. parasitica genome, the linkage group containing the MAT locus appears to harbor an extremely high level of RAPD heterogeneity and reduced recombination. Markers within this highly heterogeneous region are in linkage disequilibrium in some natural populations; however, recombination is clearly evident between this region and the MAT locus.
为了找到与栗疫病菌（Cryphonectria parasitica）中营养体不亲和性（vic）基因相关的标记，我们构建了一个初步的连锁图谱。总体而言，该图谱的特点是多态性水平较低，从观察到的24个以上的连锁群可以明显看出，而通过电泳核型分析预期为7个。尽管如此，我们发现了与两个vic基因（vic1和vic2）紧密连锁的标记，这使得它们成为定位克隆的候选对象。发现两个标记与vic2连锁：一个与vic2共分离，即它与vic2的距离为0.0厘摩，另一个距离为4.5厘摩；发现一个标记与vic1的距离为4.0厘摩。与其他三个vic基因（vic4、vic6和vic7）连锁的最紧密标记距离大于15厘摩；在能够有效定位克隆这三个vic基因之前，还需要更多的标记。与在寄生隐孢菌基因组大部分区域观察到的低多态性水平相反，包含MAT位点的连锁群似乎具有极高水平的RAPD异质性和降低的重组率。在一些自然群体中，这个高度异质区域内的标记处于连锁不平衡状态；然而，在这个区域和MAT位点之间重组明显。
