Banuett F
Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448.
Proc Natl Acad Sci U S A. 1991 May 1;88(9):3922-6. doi: 10.1073/pnas.88.9.3922.
Two master regulatory loci, a and b, govern life-cycle transitions of the phytopathogenic fungus Ustilago maydis. Fusion of haploids that differ at both a and b results in production of a filamentous dikaryon, which induces tumors in its host, maize. Here I describe identification of genes distinct from a and b that play roles in these life-cycle transitions. These studies identify three genes, fuz1, fuz2, and rtf1, that are necessary for filament formation. fuz1 is also necessary for normal size and distribution of tumors and for teliospore formation; fuz2 is also necessary for teliospore germination. Mutations in the rtf1 gene, which are recessive, bypass the requirement of different b alleles for tumor formation. This observation indicates that rtf1 codes for a negative regulator of tumor induction. The fuz1, fuz2, and rtf1 genes may be targets for the a and b loci.
两个主要调控位点a和b控制着植物病原真菌玉米黑粉菌（Ustilago maydis）的生命周期转变。在a和b位点上均存在差异的单倍体融合会产生丝状双核体，该双核体会在其宿主玉米中诱发肿瘤。在此，我描述了与a和b不同但在这些生命周期转变中起作用的基因的鉴定。这些研究鉴定出了三个基因，即fuz1、fuz2和rtf1，它们是丝状结构形成所必需的。fuz1对于肿瘤的正常大小和分布以及冬孢子形成也是必需的；fuz2对于冬孢子萌发也是必需的。rtf1基因中的突变是隐性的，可绕过不同b等位基因对肿瘤形成的需求。这一观察结果表明，rtf1编码一种肿瘤诱导的负调控因子。fuz1、fuz2和rtf1基因可能是a和b位点的作用靶点。
