Muraguchi H, Kamada T
Department of Biology, Faculty of Science, Okayama University, Okayama 700-8530, Japan.
Development. 1998 Aug;125(16):3133-41. doi: 10.1242/dev.125.16.3133.
The formation of the pileus in homobasidiomycete fungi is essential for sexual reproduction, because the pileus bears the hymenium, a layer of cells that includes the specialised basidia in which nuclear fusion, meiosis and sporulation occur. The developmental mutant ichijiku of Coprinus cinereus fails to develop a differentiated pileus at the apex of the primordial shaft, which is the basal part of the fruit-body primordia and formed in an early stage of fruit-body differentiation. Genetic analysis indicates that this phenotype is caused by a recessive mutation in a single gene (ich1). The ich1 gene was mapped to chromosome XII using restriction fragment length polymorphism markers and the marker chromosome method, and cloned by complementation using a chromosome-XII-specific cosmid library. The ich1 gene encodes a novel protein of 1,353 amino acids. The Ich1 amino-acid sequence contains nuclear targeting signals, suggesting that the Ich1 protein would function in the nucleus. Northern blot analysis indicates that the ich1 gene is specifically expressed in the pileus of the wild-type fruit-body. No ich1 mRNA was detected in the ichijiku mutant, consistent with loss of the promoter region of ich1 in the mutant genome. These data demonstrate that the ich1 gene product is essential for pileus formation.
同担子菌纲真菌菌盖的形成对于有性生殖至关重要，因为菌盖承载着子实层，这是一层包含特化担子的细胞层，在担子中会发生核融合、减数分裂和孢子形成。灰盖鬼伞的发育突变体ichijiku无法在原基轴顶端发育出分化的菌盖，原基轴是子实体原基的基部，在子实体分化的早期形成。遗传分析表明，这种表型是由单个基因（ich1）中的隐性突变引起的。利用限制性片段长度多态性标记和标记染色体法将ich1基因定位到第十二号染色体上，并使用第十二号染色体特异性黏粒文库通过互补作用进行克隆。ich1基因编码一种由1353个氨基酸组成的新蛋白质。Ich1氨基酸序列包含核定位信号，表明Ich1蛋白可能在细胞核中发挥作用。Northern印迹分析表明，ich1基因在野生型子实体的菌盖中特异性表达。在ichijiku突变体中未检测到ich1 mRNA，这与突变体基因组中ich1启动子区域的缺失一致。这些数据表明，ich1基因产物对于菌盖的形成至关重要。
