Mantle Peter
Biochemistry Department, Imperial College, London SW7 2AZ, UK.
Biology (Basel). 2020 Feb 25;9(3):41. doi: 10.3390/biology9030041.
Ergot alkaloids have an established place in plant pathology and toxicology. As pharmaceuticals, their sourcing is via natural or managed agricultural occurrence of sclerotia of (Fr.) Tul. or through industrial fermentation processes with other . The key factor for biosynthesis is differentiation of a particular mycelial anatomy. Previous study of these fungi from two disparate English grass genera, and , has shown that only mycelia expressing a plectenchymatic sclerotium-like anatomy in specific axenic culture conditions elaborated ergot alkaloids, and then only as far as lysergic acid. The present report describes sequential cycles of axenic and parasitic cultivation for wild isolates from and with intervention of a single ascospore step. This confirms the homozygous character of and defines several potential experimental axenic and parasitic conditions within the species for comparing genomic aspects of partial or full biosynthesis of cyclic tri-peptide alkaloids. Whereas ergot isolates readily parasitized rye, use of isolates as inoculum for rye ovaries failed to cause the usual sphacelial fructification but supported growth of exceptionally thin sclerotia, sometimes two in a floret, with low alkaloid content attributed to reduced medullary component. However, after two cycles of axenic and rye-parasitic cultivation, and consistent re-selection of the plectenchymatic character in axenic mycelia, typical growth of ergot sclerotia occurred on rye. Caution thus seems necessary in tests for putative host specificity in any taxonomic realignments within the classical concept of . A ergot isolate was also uniquely shown to parasitise the plumule of germinating rye seeds confirming the susceptibility of apical tissues. A key biosynthetic feature of a mycelial glyceride oil, rich in ricinoleic acid, as a prelude to axenic and parasitic formation of ergot alkaloids by is emphasised.
麦角生物碱在植物病理学和毒理学中占有既定地位。作为药物，它们的来源是通过麦角菌（Claviceps purpurea (Fr.) Tul.）菌核的天然或人工培育，或者通过与其他[未提及具体内容]的工业发酵过程。生物合成的关键因素是特定菌丝体解剖结构的分化。先前对来自两个不同英国禾本科属（Lolium和Festuca）的这些真菌的研究表明，只有在特定无菌培养条件下表现出拟薄壁组织菌核样解剖结构的菌丝体才能合成麦角生物碱，而且仅能合成到麦角酸。本报告描述了来自Lolium和Festuca的野生分离株在无菌和寄生培养的连续循环过程，其中有单个子囊孢子步骤的干预。这证实了Claviceps的纯合特性，并定义了该物种内几个潜在的实验性无菌和寄生条件，用于比较环状三肽生物碱部分或完全生物合成的基因组方面。虽然Claviceps purpurea麦角分离株很容易寄生黑麦，但将Claviceps fusiformis分离株用作黑麦子房的接种物未能导致通常的分生孢子座结实，而是支持了异常薄的菌核生长，有时一朵小花中有两个，生物碱含量低归因于髓部成分减少。然而，经过两个周期的无菌和黑麦寄生培养，并在无菌菌丝体中持续重新选择拟薄壁组织特征后，黑麦上出现了典型的麦角菌核生长。因此，在对Claviceps经典概念内任何分类重新调整中的假定宿主特异性进行测试时，似乎有必要谨慎行事。还独特地表明，一种Claviceps purpurea麦角分离株能寄生发芽黑麦种子的胚芽，证实了顶端组织的易感性。强调了富含蓖麻油酸的菌丝体甘油酯油作为Claviceps进行无菌和寄生形成麦角生物碱前奏的关键生物合成特征。
