Asexuality in Fusarium oxysporum: Mechanisms and Relationship between Pathogenicity-Diversity

采用聚合酶链反应（pcr）方法，从无性子囊菌尖孢镰刀菌（Fusarium oxysporum）和alternnaria alternata中克隆了交配型（MAT）基因座。将尖孢赤霉素基因组MAT位点的结构与尖孢赤霉素的性亲缘菌株藤黑赤霉素的基因组MAT位点进行了比较。MAT1-1 idiomorph编码的3个基因（MAT1-1- 1、MAT1-1-2和MAT1-1-3）在两种间高度同源；MAT1-2 idiomorph编码单一的MAT1-2-1基因，该基因在种间也是同源的。在MM培养基上培养无性尖孢镰刀菌时，所有MAT基因均在无性尖孢镰刀菌中表达，在有性尖孢镰刀菌中表达。在MM培养基上也表达了黄菖蒲MAT基因（MAT1-1-1和MAT1-2-1），并通过异源表达证实了这两个基因的功能。这些结果表明子囊菌无性行为的原因不依赖于MAT位点。

Mating type (MAT) loci were cloned from asexual ascomycetes Fusarium oxysporum and Alternaria alternata by PCR-based strategy. Structure of the MAT loci in the genome of F. oxysporum was compared to that of Gibberella fujikuroi, a sexual relative of F. oxysporum. MAT1-1 idiomorph encodes three genes (Mat1-1-1, MAT1-1-2, and MAT1-1-3) which were highly homologous between the two species; MAT1-2 idiomorph encodes single MAT1-2-1 gene that was also homologous between the species. All of the MAT genes were confirmed to be expressed in asexual F. oxysporum when it was cultured on MM medium as well as in the sexual G. fujikuroi. A. alternata MAT genes (MAT1-1-1 and MAT1-2-1) were also expressed on MM medium and moreover both genes were proved to be functional by heterologous expression in Cochliobolus heterostrophus. These results suggested that the cause of asexuality in ascomycetes does not depend on MAT loci.