The antifungal action mode of the rice endophyte Streptomyces hygroscopicus OsiSh-2 as a potential biocontrol agent against the rice blast pathogen

Ting Xu, Lidan Cao, Jiarui Zeng, Christopher M.M. Franco, Yuanzhu Yang, Xiaochun Hu, Ying Liu, Xiang Wang, Yan Gao, Zhigang Bu, Liming Shi, Guoying Zhou, Qian Zhou, Xuanming Liu, Yonghua Zhu

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Microbial antagonists and their bioactive metabolites provide one of the best alternatives to chemical pesticides to control crop disease for sustainable agriculture and global food security. The rice endophyte Streptomyces hygroscopicus OsiSh-2, with remarkable antagonistic activity towards the rice blast fungus Magnaporthe oryzae, was reported in our previous study. The present study deciphered the possible direct interaction mode of OsiSh-2 against M. oryzae. An in vitro antibiotic assay for OsiSh-2 culture filtrate revealed strong suppression of mycelial growth, conidial germination and appressorial formation of M. oryzae. Meanwhile, severe morphological and internal abnormalities in M. oryzae hyphae were observed under a scanning electron microscope and transmission electron microscope. Foliar treatment of rice seedlings by OsiSh-2 culture filtrate in the greenhouse and in the field showed 23.5% and 28.3% disease reduction, respectively. Correspondingly, OsiSh-2 culture filtrate could induce disorganized chitin deposition in the cell wall and lowered ergosterol content in the cell membrane of M. oryzae. Additionally, cell wall integrity pathway activation, large cell electrolytes release, reactive oxygen species accumulation and tricarboxylic acid cycle-related enzyme activity changes were found in M. oryzae. All these results suggested that the direct antagonistic activity of OsiSh-2 against M. oryzae may be attributed to damaging the integrity of the cell wall and membrane and disrupting mitochondrial function in the pathogen.

Original languageEnglish
Pages (from-to)58-69
Number of pages12
JournalPesticide Biochemistry and Physiology
Volume160
DOIs
Publication statusPublished - Oct 2019

Keywords

  • Antifungal activity
  • Endophyte
  • Magnaporthe oryzae
  • Mode of action
  • Streptomyces hygroscopicus OsiSh-2

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