Department of Plant Pathology and Microbiology, Program in Biochemistry and Molecular Biology, University of California, Riverside, California 92521, USA.
Genetics. 2012 Apr;190(4):1389-404. doi: 10.1534/genetics.111.136358. Epub 2012 Jan 31.
Here we characterize the relationship between the PRE-2 pheromone receptor and its ligand, CCG-4, and the general requirements for receptors, pheromones, G proteins, and mating type genes during fusion of opposite mating-type cells and sexual sporulation in the multicellular fungus Neurospora crassa. PRE-2 is highly expressed in mat a cells and is localized in male and female reproductive structures. Δpre-2 mat a females do not respond chemotropically to mat A males (conidia) or form mature fruiting bodies (perithecia) or meiotic progeny (ascospores). Strains with swapped identity due to heterologous expression of pre-2 or ccg-4 behave normally in crosses with opposite mating-type strains. Coexpression of pre-2 and ccg-4 in the mat A background leads to self-attraction and development of barren perithecia without ascospores. Further perithecial development is achieved by inactivation of Sad-1, a gene required for meiotic gene silencing. Findings from studies involving forced heterokaryons of opposite mating-type strains show that presence of one receptor and its compatible pheromone is necessary and sufficient for perithecial development and ascospore production. Taken together, the results demonstrate that although receptors and pheromones control sexual identity, the mating-type genes (mat A and mat a) must be in two different nuclei to allow meiosis and sexual sporulation to occur.
在这里，我们描述了 PRE-2 信息素受体与其配体 CCG-4 之间的关系，以及在多细胞真菌 Neurospora crassa 中相反交配型细胞融合和有性孢子形成过程中，受体、信息素、G 蛋白和交配型基因的一般要求。PRE-2 在 mat a 细胞中高度表达，并定位于雄性和雌性生殖结构中。Δpre-2 mat a 雌性对 mat A 雄性（分生孢子）或形成成熟的子实体（子囊壳）或减数分裂后代（子囊孢子）不表现出化学趋向性。由于 pre-2 或 ccg-4 的异源表达而导致身份交换的菌株在与相反交配型菌株的杂交中表现正常。pre-2 和 ccg-4 在 mat A 背景下的共表达导致自我吸引和无孢子的贫瘠子囊壳的发育。进一步的子囊壳发育是通过 Sad-1 的失活实现的，Sad-1 是减数基因沉默所必需的基因。涉及相反交配型菌株强制异核体的研究结果表明，一个受体及其相容的信息素的存在对于子囊壳的发育和子囊孢子的产生是必要的和充分的。总之，这些结果表明，尽管受体和信息素控制着性别的身份，但交配型基因（mat A 和 mat a）必须存在于两个不同的核中，才能允许减数分裂和有性孢子形成发生。
