De Fine Licht Henrik H, Andersen Anders, Aanen Duur K
Department of Population Biology, Biological Institute, University of Copenhagen, DK-2100 Copenhagen O, Denmark.
Mycol Res. 2005 Mar;109(Pt 3):314-8. doi: 10.1017/s0953756204001844.
Fungi of the genus Termitomyces live in an obligate symbiosis with termites of the subfamily Macrotermitinae. Many species of Termitomyces frequently form fruit bodies, which develop from the fungus comb within the nest. In this study, we determined the mating system of a species of Termitomyces associated with the South African termite Macrotermes natalensis. Termite nests were excavated and a Termitomyces sp. was isolated into pure culture from the asexual fruit bodies (nodules) growing in the fungus gardens. For one strain, single basidiospore cultures were obtained from basidiomes growing from the fungus comb after incubation without termites. Using nuclear staining, we show that both comb cultures and single spore cultures have multinucleate cells and that the majority of spores has a single nucleus. However, DNA sequencing of the ITS region in the nuclear RNA gene revealed that the comb mycelium had two different ITS types that segregated in the single spore cultures, which consequently had only a single ITS type. These results unambiguously prove that the strain of Termitomyces studied here has a heterothallic mating system, with the fungus garden of the termite mound being in the heterokaryotic phase. This is the first time the mating system of a Termitomnyces species has been studied.
鸡枞菌属真菌与大白蚁亚科的白蚁存在专性共生关系。许多鸡枞菌物种经常形成子实体，这些子实体从蚁巢内的菌圃发育而来。在本研究中，我们确定了一种与南非白蚁纳塔尔大白蚁相关的鸡枞菌的交配系统。挖掘白蚁巢，并从菌圃中生长的无性子实体（瘤）中分离出一种鸡枞菌并进行纯培养。对于一个菌株，在无白蚁的情况下培养后，从菌圃中生长的担子果获得了单担孢子培养物。通过核染色，我们发现菌圃培养物和单孢子培养物都有多核细胞，并且大多数孢子只有一个细胞核。然而，对核RNA基因中ITS区域的DNA测序显示，菌圃菌丝体有两种不同的ITS类型，它们在单孢子培养物中分离，因此单孢子培养物只有一种ITS类型。这些结果明确证明，这里研究的鸡枞菌菌株具有异宗配合的交配系统，白蚁丘的菌圃处于异核体阶段。这是首次对鸡枞菌物种的交配系统进行研究。
