Institute of Biotechnology and Genetic Engineering, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh.
PLoS One. 2020 Aug 17;15(8):e0233665. doi: 10.1371/journal.pone.0233665. eCollection 2020.
Oligomycins are macrolide antibiotics, produced by Streptomyces spp. that show antagonistic effects against several microorganisms such as bacteria, fungi, nematodes and the oomycete Plasmopara viticola. Conidiogenesis, germination of conidia and formation of appressoria are determining factors pertaining to pathogenicity and successful diseases cycles of filamentous fungal phytopathogens. The goal of this research was to evaluate the in vitro suppressive effects of two oligomycins, oligomycin B and F along with a commercial fungicide Nativo® 75WG on hyphal growth, conidiogenesis, conidial germination, and appressorial formation of the wheat blast fungus, Magnaporthe oryzae Triticum (MoT) pathotype. We also determined the efficacy of these two oligomycins and the fungicide product in vivo in suppressing wheat blast with a detached leaf assay. Both oligomycins suppressed the growth of MoT mycelium in a dose dependent manner. Between the two natural products, oligomycin F provided higher inhibition of MoT hyphal growth compared to oligomycin B with a minimum inhibitory concentration of 0.005 and 0.05 μg/disk, respectively. The application of the compounds completely halted conidial formation of the MoT mycelium in agar medium. Further bioassays showed that these compounds significantly inhibited MoT conidia germination and induced lysis. The compounds also caused abnormal germ tube formation and suppressed appressorial formation of germinated spores. Interestingly, the application of these macrolides significantly inhibited wheat blast on detached leaves of wheat. This is the first report on the inhibition of mycelial growth, conidiogenesis, germination of conidia, deleterious morphological changes in germinated conidia, and suppression of blast disease of wheat by oligomycins from Streptomyces spp. Further study is needed to unravel the precise mode of action of these natural compounds and consider them as biopesticides for controlling wheat blast.
寡霉素是由链霉菌属产生的大环内酯类抗生素，对细菌、真菌、线虫和卵菌纲病原菌葡萄生疫霉等多种微生物具有拮抗作用。分生孢子的形成、萌发和附着胞的形成是与丝状真菌植物病原菌致病性和成功疾病循环有关的决定因素。本研究的目的是评估两种寡霉素（寡霉素 B 和 F）以及一种商业杀真菌剂 Nativo® 75WG 对小麦赤霉病菌（MoT）的菌丝生长、分生孢子形成、孢子萌发和附着胞形成的体外抑制作用。我们还通过离体叶片测定法测定了这两种寡霉素和杀真菌剂产品在体内抑制小麦赤霉病的功效。两种寡霉素都以剂量依赖的方式抑制 MoT 菌丝生长。在这两种天然产物中，寡霉素 F 对 MoT 菌丝生长的抑制作用高于寡霉素 B，最低抑菌浓度分别为 0.005 和 0.05 μg/disk。这些化合物的应用完全阻止了 MoT 菌丝在琼脂培养基中的分生孢子形成。进一步的生物测定表明，这些化合物显著抑制了 MoT 分生孢子的萌发，并诱导了裂解。这些化合物还导致异常的芽管形成，并抑制了萌发孢子的附着胞形成。有趣的是，这些大环内酯类化合物的应用显著抑制了小麦叶片上的小麦赤霉病。这是首次报道寡霉素抑制小麦赤霉病菌的菌丝生长、分生孢子形成、孢子萌发、萌发孢子的有害形态变化以及抑制小麦赤霉病。需要进一步的研究来揭示这些天然化合物的确切作用模式，并考虑将它们作为防治小麦赤霉病的生物农药。
