Yun S H, Berbee M L, Yoder O C, Turgeon B G
Department of Plant Pathology, Cornell University, 334 Plant Science Building, Ithaca, NY 14853, USA.
Proc Natl Acad Sci U S A. 1999 May 11;96(10):5592-7. doi: 10.1073/pnas.96.10.5592.
In most fungal ascomycetes, mating is controlled by a single locus (MAT). Fungi requiring a partner to mate are heterothallic (self-sterile); those not requiring a partner are homothallic (self-fertile). Structural analyses of MAT sequences from homothallic and heterothallic Cochliobolus species support the hypothesis that heterothallism is ancestral. Homothallic species carry both MAT genes in a single nucleus, usually closely linked or fused, in contrast to heterothallic species, which have alternate MAT genes in different nuclei. The structural organization of MAT from all heterothallic species examined is highly conserved; in contrast, the organization of MAT in each homothallic species is unique. The mechanism of conversion from heterothallism to homothallism is a recombination event between islands of identity in otherwise dissimilar MAT sequences. Expression of a fused MAT gene from a homothallic species confers self-fertility on a MAT-null strain of a heterothallic species, suggesting that MAT alone is sufficient to change reproductive life style.
在大多数子囊菌纲真菌中，交配由单个基因座（MAT）控制。需要伴侣进行交配的真菌是异宗配合的（自交不育）；不需要伴侣的是同宗配合的（自交可育）。对同宗配合和异宗配合的旋孢腔菌属物种的MAT序列进行的结构分析支持了异宗配合是祖先状态这一假说。与在不同细胞核中具有交替MAT基因的异宗配合物种相反，同宗配合物种在单个细胞核中携带两个MAT基因，通常紧密连锁或融合。所有已检测的异宗配合物种的MAT结构组织高度保守；相比之下，每个同宗配合物种中的MAT组织是独特的。从异宗配合转变为同宗配合的机制是在其他方面不同的MAT序列中的相同区域之间发生的重组事件。来自同宗配合物种的融合MAT基因的表达赋予异宗配合物种的MAT缺失菌株自交可育性，这表明仅MAT就足以改变生殖生活方式。
