Mushroom Research Division, National Institute of Horticultural and Herbal Science, Rural Development Administration, Suwon, Republic of Korea.
PLoS One. 2011;6(7):e22249. doi: 10.1371/journal.pone.0022249. Epub 2011 Jul 20.
Mating-type loci of mushroom fungi contain master regulatory genes that control recognition between compatible nuclei, maintenance of compatible nuclei as heterokaryons, and fruiting body development. Regions near mating-type loci in fungi often show adapted recombination, facilitating the generation of novel mating types and reducing the production of self-compatible mating types. Compared to other fungi, mushroom fungi have complex mating-type systems, showing both loci with redundant function (subloci) and subloci with many alleles. The genomic organization of mating-type loci has been solved in very few mushroom species, which complicates proper interpretation of mating-type evolution and use of those genes in breeding programs.
METHODOLOGY/PRINCIPAL FINDINGS: We report a complete genetic structure of the mating-type loci from the tetrapolar, edible mushroom Flammulina velutipes mating type A3B3. Two matB3 subloci, matB3a that contains a unique pheromone and matB3b, were mapped 177 Kb apart on scaffold 1. The matA locus of F. velutipes contains three homeodomain genes distributed over 73 Kb distant matA3a and matA3b subloci. The conserved matA region in Agaricales approaches 350 Kb and contains conserved recombination hotspots showing major rearrangements in F. velutipes and Schizophyllum commune. Important evolutionary differences were indicated; separation of the matA subloci in F. velutipes was diverged from the Coprinopsis cinerea arrangement via two large inversions whereas separation in S. commune emerged through transposition of gene clusters.
CONCLUSIONS/SIGNIFICANCE: In our study we determined that the Agaricales have very large scale synteny at matA (∼350 Kb) and that this synteny is maintained even when parts of this region are separated through chromosomal rearrangements. Four conserved recombination hotspots allow reshuffling of large fragments of this region. Next to this, it was revealed that large distance subloci can exist in matB as well. Finally, the genes that were linked to specific mating types will serve as molecular markers in breeding.
蘑菇真菌的交配型基因座包含主控调节基因，这些基因控制着相容核之间的识别、相容核作为异核体的维持以及子实体的发育。真菌交配型基因座附近的区域通常表现出适应性重组，促进新交配型的产生，并减少自交配型的产生。与其他真菌相比，蘑菇真菌具有复杂的交配型系统，表现出既有功能冗余的基因座（亚基因座），也有具有许多等位基因的亚基因座。交配型基因座的基因组组织在极少数蘑菇物种中得到了解决，这使得正确解释交配型进化以及在育种计划中使用这些基因变得复杂。
方法/主要发现：我们报道了四极性可食用蘑菇金针菇交配型 A3B3 的交配型基因座的完整遗传结构。两个 matB3 亚基因座，matB3a 含有独特的信息素，matB3b，被映射在 177 Kb 之外的 1 号支架上。金针菇的 matA 基因座包含三个分布在 73 Kb 之外的同源域基因，分为 matA3a 和 matA3b 亚基因座。Agaricales 中的保守 matA 区域接近 350 Kb，包含保守的重组热点，在金针菇和裂褶菌中发生了重大重排。重要的进化差异表明；金针菇 matA 亚基因座的分离是通过两次大反转从 Coprinopsis cinerea 排列中分化出来的，而裂褶菌的分离则是通过基因簇的转座产生的。
结论/意义：在我们的研究中，我们确定 Agaricales 在 matA（约 350 Kb）具有非常大的规模同线性，即使该区域的部分通过染色体重排而分离，这种同线性仍然得以维持。四个保守的重组热点允许该区域的大片段重新排列。除此之外，还揭示了 matB 中也可以存在大距离的亚基因座。最后，与特定交配型相关的基因将作为育种中的分子标记。
