Medicinal plants of the genus Hypericum are rich sources of bioactive naphthodianthrones, which are unique in the plant kingdom, but quite common in fungal endophytes. Cultivable endophytic fungi were isolated from 14 different Hypericum spp. originating from seeds grown under in vitro conditions and further acclimated to outdoor conditions. Among 37 fungal isolates yielded from the aerial and underground plant organs, 25 were identified at the species level by the fungal barcode marker internal transcribed spacer rDNA and protein-coding gene region of tef1α. Ten of them were isolated from Hypericum spp. for the first time. The axenic cultures of the isolated endophytes were screened for the production of extracellular enzymes, as well as bioactive naphthodianthrones and their putative precursors by Bornträger's test and HPLC-HRMS. Traces of naphthodianthrones and their intermediates, emodin, emodin anthrone, skyrin, or pseudohypericin, were detected in the fungal mycelia of Acremonium sclerotigenum and Plectosphaerella cucumerina isolated from Hypericum perforatum and Hypericum maculatum, respectively. Traces of emodin, hypericin, and pseudohypericin were released in the broth by Scedosporium apiospermum, P. cucumerina, and Fusarium oxysporum during submerged fermentation. These endophytes were isolated from several hypericin-producing Hypericum spp. Taken together, our results reveal the biosynthetic potential of cultivable endophytic fungi harbored in Hypericum plants as well as evidence of the existence of remarkable plant-endophyte relationships in selected non-native ecological niches. A possible role of the extracellular enzymes in plant secondary metabolism is discussed.

中文翻译：

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14 种种子衍生金丝桃属植物内生真菌的分离、表征和靶向代谢评估

金丝桃属的药用植物是生物活性萘并蒽酮的丰富来源，这在植物界是独一无二的，但在内生真菌中很常见。从 14 种不同的金丝桃属植物中分离出可培养的内生真菌。源自在体外条件下生长并进一步适应户外条件的种子。在从地上和地下植物器官产生的 37 株真菌分离物中，有 25 株通过真菌条码标记内部转录间隔区 rDNA 和 tef1α 的蛋白质编码基因区在物种水平上鉴定。其中十个是从金丝桃属植物中分离出来的。首次。通过 Bornträger 测试和 HPLC-HRMS 筛选分离的内生菌的无菌培养物以生产胞外酶以及生物活性萘二酮及其推定的前体。在分别从贯叶连翘和黄连金丝桃中分离的核枝头孢菌和黄瓜果球藻的真菌菌丝体中检测到微量的萘二酮及其中间体大黄素、大黄素蒽酮、skyrin 或假金丝桃素。在深层发酵过程中，Scedosporium apiospermum、P. cucumerina 和 Fusarium oxysporum 在肉汤中释放出微量的大黄素、金丝桃素和假金丝桃素。这些内生菌是从几种产金丝桃素的金丝桃属植物中分离出来的。总之，我们的结果揭示了金丝桃属植物中可培养的内生真菌的生物合成潜力，以及在选定的非本地生态位中存在显着植物-内生菌关系的证据。