Wang Weizhen, Cui Tongshan, Zhang Fan, Xue Zhaolin, Zhang Borui, Liu Xili
Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China.
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling, China.
Front Microbiol. 2022 May 10;13:811132. doi: 10.3389/fmicb.2022.811132. eCollection 2022.
Although sterols play an important role in most eukaryotes, some oomycetes, including spp., have lost the sterol synthesis pathway. Nevertheless, the gene encoding C-5 sterol desaturase in the sterol synthesis pathway is still present in the genomes of spp. , a destructive pathogen with a broad range of plant hosts, poses a significant threat to the production of agriculture. This study focused on the gene in () and explored its function in this pathogen. It showed that the gene could be expressed in all tested developmental stages of , with sporangium and mycelium displaying higher expression levels. A potential substrate of Erg3 (stellasterol) was used to treat the wild-type strain and a Δ transformant, and their sterol profiles were determined by GC-MS. The wild-type strain could convert stellasterol into the down-stream product while the transformant could not, indicating that PcErg3 retains the C-5 sterol desaturase activity. By comparing the biological characteristics of different strains, it was found that is not important for the development of . The pathogenicity of the Δ transformants and the wild-type strain was comparable, suggesting that is not necessary for the interaction between and its hosts. Further investigations revealed that the Δ transformants and the wild-type strain displayed a similar level of tolerance to external adversities such as unsuitable temperatures, high osmotic pressures, and intemperate pH, signifying that is not essential for to cope with these environmental stresses.
尽管甾醇在大多数真核生物中发挥着重要作用，但一些卵菌，包括 种，已经失去了甾醇合成途径。然而，甾醇合成途径中编码C-5甾醇去饱和酶的 基因仍存在于 种的基因组中， 种是一种具有广泛植物宿主的毁灭性病原体，对农业生产构成重大威胁。本研究聚焦于 中的 基因，并探究其在该病原体中的功能。结果表明， 基因可在 的所有测试发育阶段表达，孢子囊和菌丝体的表达水平较高。使用Erg3的一种潜在底物（海星甾醇）处理 野生型菌株和一个Δ 转化体，并通过气相色谱-质谱联用仪（GC-MS）测定它们的甾醇谱。野生型菌株可将海星甾醇转化为下游产物，而转化体则不能，这表明PcErg3保留了C-5甾醇去饱和酶活性。通过比较不同菌株的生物学特性，发现 对 的发育并不重要。Δ 转化体和野生型菌株的致病性相当，这表明 对于 与其宿主之间的相互作用并非必需。进一步研究表明，Δ 转化体和野生型菌株对诸如不适宜温度、高渗透压和不适宜pH等外部逆境表现出相似的耐受水平，这意味着 对于 应对这些环境胁迫并非必不可少。
