Microorganisms of all three domains show specifi c adaptations, which make them prone to show high diversity. Within the Eukarya, the fungal kingdom with about 2.8 Mio species expected is the second largest group, only insects seem to have evolved higher divergency on species level. This might well be due to the easier distinction of interbreeding with insects as compared to fungi, and thus the valid species description is limited in fungi owing to the fact that the defi nition of species is based on a population that is interbreeding, and separated from other species. Aside from the measure of species number, diversity is clearly linked to diff erent functions. Fungi are well known to be able to survive and even thrive under extreme conditions, like, e.g., in lichen that live stones in full sun. The lichen symbiosis already shows that fungi are also prone to undergo interactions with plants, in symbiotic, commensal or pathogenic symbioses. The current boost of knowledge on endophytic fungi is crediting this fact. With endophytes, however, it seems important to observe that mere isolation from surface-sterilized plant material is not suffi cient to confi rm an endophytic nature. In this issue, an endophytic growth of a fungus in an orchid has been shown that also confi rms another observation often made with respect to growth in plant: the continuum from benefi cial to pathogenic interactions may be seen depending on environmental conditions with respect to plant-associated fungi (Hajong and Kapoor, this issue). Not only within a plant, but often associated to a response to environmental conditions, fungi are well known to form secondary metabolites. Polyketides are one class of compounds that include antibiotics and pigments, as well as other useful natural products. The formation of these secondary metabolites is linked to the large family of polyketide synthases, or Pks enzymes. One such large protein encoded by the pks1 gene has been targeted with real time PCR for detection and quantifi cation in an ascomycete fungus (Gherbawy et al., this issue). And lastly, the isolation of fungi from extreme environments already in the past often led to the discovery of new enzymatic properties, including the formation of new natural products. Areas, where large surveys are lacking may thus provide new strains that can be fruitfully exploited in biotechnology. Here, fungi from the Hindukush mountains are addressed to fi nd candidates for biotechnological application (Rafi q et al., this issue). With this Special Focus, the journal can only give a small glimpse into the vast diversity of fungi and their potentials. We hope that this selection will enhance the interest in fungal natural diversity.

中文翻译：

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特别关注：真菌多样性

所有三个领域的微生物都表现出特定的适应性，这使得它们容易表现出高度的多样性。在真核生物中，预计约有 2.8 种 Mio 物种的真菌王国是第二大类群，似乎只有昆虫在物种水平上进化出更高的差异性。这很可能是由于与真菌相比更容易区分昆虫与昆虫的杂交，因此有效的物种描述仅限于真菌，因为物种的定义基于杂交的种群，并且与真菌分离。其他物种。除了物种数量的衡量之外，多样性显然与不同的功能有关。众所周知，真菌能够在极端条件下生存甚至茁壮成长，例如在阳光充足的地衣中存活的石头。地衣共生已经表明真菌也容易与植物发生相互作用，在共生、共生或致病共生中。目前对内生真菌知识的增长归功于这一事实。然而，对于内生菌，观察到仅从表面灭菌的植物材料中分离并不足以确认内生菌的性质似乎很重要。在本期杂志中，一种真菌在兰花中的内生生长已被证实，这也证实了另一个关于植物生长的观察结果：根据植物的环境条件，可以看到从有益到致病相互作用的连续性-相关真菌（Hajong 和 Kapoor，本期）。不仅在工厂内，而且通常与对环境条件的反应有关，众所周知，真菌会形成次级代谢产物。聚酮化合物是一类化合物，包括抗生素和色素，以及其他有用的天然产物。这些次级代谢物的形成与聚酮合酶或 Pks 酶的大家族有关。由 pks1 基因编码的一种这样的大蛋白质已被实时 PCR 靶向，用于在子囊菌真菌中进行检测和定量（Gherbawy 等人，本期）。最后，过去已经将真菌从极端环境中分离出来，这通常会导致发现新的酶特性，包括新天然产物的形成。因此，缺乏大规模调查的地区可能会提供可以在生物技术中富有成效地开发的新菌株。这里，来自兴都库什山脉的真菌旨在寻找生物技术应用的候选者（Rafi q 等人，本期）。有了这个特别焦点，该杂志只能对真菌的巨大多样性及其潜力进行一瞥。我们希望这种选择将增强对真菌自然多样性的兴趣。