Wallen R Margaret, Richardson Kirsten, Furnish Madison, Mendoza Hector, Dentinger Allison, Khanal Sunita, Perlin Michael H
Department of Biology, Program on Disease Evolution, University of Louisville, Louisville, KY 40292, USA.
J Fungi (Basel). 2021 Feb 12;7(2):135. doi: 10.3390/jof7020135.
Mating-types allow single-celled eukaryotic organisms to distinguish self from non-self in preparation for sexual reproduction. The components of mating-type loci provide initial self/non-self-recognition through pheromone and receptor interactions that control early cell fusion events. However, they may also provide a second level of scrutiny that requires differences in alleles leading to production of a transcription factor required for successful downstream developmental pathways after initial cell fusion. Interestingly, the protein subunits of these transcription factors have not been thoroughly examined for their roles, if any, in the haploid cells themselves. In , the causative agent of galls in maize plants, the locus, encoding bEast (bE) and bWest (bW), components of the eventual requisite transcription factor, has been extensively studied for its role in formation of the stable dikaryon after mating and subsequent pathogenic program. Little is known, however, about any roles for bE or bW in haploid cells. Since mating in fungi is often induced under conditions of nitrogen starvation, we have explored connections between the locus and the nitrogen-sensing and response pathways in . We previously identified a connection in haploid cells between the locus and Ump2, the high-affinity transceptor, a protein that both transports ammonium and triggers filamentous growth as a response to nitrogen starvation. Deletion of the entire locus abrogates the filamentous response to low ammonium, a phenotype that is rescued by overexpression of Ump2. Here we further investigated the individual roles of bE and bW in haploid cells. We show that bE and bW are expressed differentially in haploid cells starved for ammonium. Their respective deletion elicits different effects on transcription of mating and pathogenic-related genes and, importantly, on the degree of pathogenic development in host plants. This is the first demonstration of a role for these mating locus components on haploid development and the first to demonstrate a connection to the ammonium transceptors.
交配型使单细胞真核生物能够在准备有性繁殖时区分自我与非自我。交配型位点的组成部分通过控制早期细胞融合事件的信息素和受体相互作用提供初始的自我/非自我识别。然而，它们也可能提供第二层审查，这需要等位基因存在差异，从而导致在初始细胞融合后成功的下游发育途径所需的转录因子产生。有趣的是，这些转录因子的蛋白质亚基在单倍体细胞本身中的作用（如果有）尚未得到彻底研究。在玉米植物中引起瘿瘤的病原体黑粉菌中，编码最终必需转录因子组成部分的bEast（bE）和bWest（bW）的位点，已被广泛研究其在交配后稳定双核体形成及随后致病程序中的作用。然而，关于bE或bW在单倍体细胞中的任何作用却知之甚少。由于真菌中的交配通常在氮饥饿条件下诱导，我们探索了黑粉菌中该位点与氮感应和反应途径之间的联系。我们之前在单倍体细胞中发现了该位点与Ump2（高亲和力转运受体，一种既能转运铵又能触发丝状生长以响应氮饥饿的蛋白质）之间的联系。删除整个该位点会消除对低铵的丝状反应，这种表型可通过Ump2的过表达来挽救。在这里，我们进一步研究了bE和bW在单倍体细胞中的各自作用。我们表明，bE和bW在铵饥饿的单倍体细胞中差异表达。它们各自的缺失对交配和致病相关基因的转录产生不同影响，重要的是，对宿主植物中的致病发育程度也有不同影响。这是首次证明这些交配位点成分在单倍体发育中的作用，也是首次证明与铵转运受体的联系。
