Mir-Rashed N, Jacobson D J, Dehghany M R, Micali O C, Smith M L
Biology Department, Carleton University, Ottawa, Ontario K1S 5B6, Canada.
Fungal Genet Biol. 2000 Aug;30(3):197-205. doi: 10.1006/fgbi.2000.1218.
Two closely linked genes, un-24 and het-6, associated with the het-6 heterokaryon incompatibility functional haplotype were examined in 40 Neurospora crassa strains from a Louisiana sugarcane field. Partial diploid analyses were used to determine that half of the strains were functionally Oak Ridge (OR) and half were non-OR and indistinguishable from the standard Panama (PA) form. PCR-based markers were developed to identify polymorphisms within both un-24 and het-6. Two common forms of each gene occur based on these molecular markers. Rare forms of both un-24 and het-6 were identified as variants of the non-OR form by a DNA transformation assay. The heterokaryon incompatibility function of haplotypes, based on partial diploid analyses, was perfectly correlated with the PCR-based markers at both loci. This correlation indicates that the two loci are in severe linkage disequilibrium in this population sample and may act as an incompatibility gene complex. Southern hybridizations using OR- and PA-derived cloned probes from the region that spans un-24 and het-6 showed that the apparent absence of recombination in this approximately 25-kbp region is associated with low levels of overall sequence identity between the PA and OR forms.
在来自路易斯安那甘蔗田的40株粗糙脉孢菌菌株中，研究了与het-6异核体不相容功能单倍型相关的两个紧密连锁基因un-24和het-6。采用部分二倍体分析确定，一半的菌株在功能上是橡树岭（OR）型，另一半是非OR型，且与标准巴拿马（PA）型无法区分。开发了基于PCR的标记来鉴定un-24和het-6内的多态性。基于这些分子标记，每个基因出现了两种常见形式。通过DNA转化试验，un-24和het-6的罕见形式被鉴定为非OR型的变体。基于部分二倍体分析，单倍型的异核体不相容功能与两个位点基于PCR的标记完全相关。这种相关性表明，在这个群体样本中，这两个位点处于严重的连锁不平衡状态，可能作为一个不相容基因复合体起作用。使用来自跨越un-24和het-6区域的OR型和PA型克隆探针进行的Southern杂交表明，在这个约25kbp的区域中明显缺乏重组，这与PA型和OR型之间总体序列同一性水平较低有关。
